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RSS2010 Vol. 22, No. 04
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2010,
22.
Abstract:
The output power and control modes of the high-frequency commutated resonant converter were derived through the theoretical research on its charging and discharging processes. The numerical simulation was conducted by using Simulink of Matlab to build its full-circuit model. Simulation results show that the current and voltage waveforms of nodes agree with theoretical values during the resonant charging and discharging processes.
The output power and control modes of the high-frequency commutated resonant converter were derived through the theoretical research on its charging and discharging processes. The numerical simulation was conducted by using Simulink of Matlab to build its full-circuit model. Simulation results show that the current and voltage waveforms of nodes agree with theoretical values during the resonant charging and discharging processes.
2010,
22.
Abstract:
This paper introduces the basic characteristic parameter of 200 kV water dielectric high voltage pulse delay-line, whose characteristic impedance is 23.4 Ω and electrical length is 300 ns. It analyzes breakdown characteristic of the delay-line and estimates height attenuation rate of the pulse transmitted by the delay-line. An experiment equipment of high voltage pulse delay-line has been designed and machined, and the experiment research has been made. In the experiment, Blumlein line generated the high voltage pulse which was transited by two paths. One path is from high voltage cable to delay-line to high voltage cable to matched load and the other path is from high voltage cable to matched load. The pulses from the two loads are regarded as the output pulse and input pulse of delay-li
This paper introduces the basic characteristic parameter of 200 kV water dielectric high voltage pulse delay-line, whose characteristic impedance is 23.4 Ω and electrical length is 300 ns. It analyzes breakdown characteristic of the delay-line and estimates height attenuation rate of the pulse transmitted by the delay-line. An experiment equipment of high voltage pulse delay-line has been designed and machined, and the experiment research has been made. In the experiment, Blumlein line generated the high voltage pulse which was transited by two paths. One path is from high voltage cable to delay-line to high voltage cable to matched load and the other path is from high voltage cable to matched load. The pulses from the two loads are regarded as the output pulse and input pulse of delay-li
2010,
22.
Abstract:
The rep-rate wire-plane corona plasma generator experimental platform has been constructed. The platform consists of resonant charging circuit, pulse step up transformer, and magnetic switch for output pulse width adjustment. The platform can generate pulses with 150 kV peak voltage, 0.53 μs rise time, 1 kHz rep-rate and 5～25 μs adjustable pulsed-width. The paper describes the scheme of pulsed-transformer-type power modulator and output pulse-width adjustment. According to the analysis of experimental results, distributed capacitance of pulse transformer’s primary and secondary windings is the main factor affecting power efficiency. At last, this paper, gives out several critical points to improve this type of corona plasma generator.
The rep-rate wire-plane corona plasma generator experimental platform has been constructed. The platform consists of resonant charging circuit, pulse step up transformer, and magnetic switch for output pulse width adjustment. The platform can generate pulses with 150 kV peak voltage, 0.53 μs rise time, 1 kHz rep-rate and 5～25 μs adjustable pulsed-width. The paper describes the scheme of pulsed-transformer-type power modulator and output pulse-width adjustment. According to the analysis of experimental results, distributed capacitance of pulse transformer’s primary and secondary windings is the main factor affecting power efficiency. At last, this paper, gives out several critical points to improve this type of corona plasma generator.
2010,
22.
Abstract:
Three technical approaches were presented for the MHz repetition rate burst high-voltage generator. The solid-state driver is based on the idea of using field effect transistor (FET) array and inductive adder to switch energy from a pre-charged capacitor bank to a load. In this way, output voltage with an amplitude of 6.2 kV, a repetition rate of 2.5 MHz was achieved. Pulse forming lines (PFLs), which are connected in series by large diaphragm switches, can produce multiple pulses. The as-developed system produced two 200 kV pulses separated by 500 ns. Especially designed blocking networks consisting of power diodes can combine several isolated pulses into a bunch. And three 275 kV pulses separated by 500 ns were achieved.
Three technical approaches were presented for the MHz repetition rate burst high-voltage generator. The solid-state driver is based on the idea of using field effect transistor (FET) array and inductive adder to switch energy from a pre-charged capacitor bank to a load. In this way, output voltage with an amplitude of 6.2 kV, a repetition rate of 2.5 MHz was achieved. Pulse forming lines (PFLs), which are connected in series by large diaphragm switches, can produce multiple pulses. The as-developed system produced two 200 kV pulses separated by 500 ns. Especially designed blocking networks consisting of power diodes can combine several isolated pulses into a bunch. And three 275 kV pulses separated by 500 ns were achieved.
2010,
22.
Abstract:
The method of using magnetic switches is proposed to reduce the voltage rise time of the all solid-state pulse source and a generator is constructed. This generator consists of a Marx modulator based on isolated gate bipolar thyristor (IGBT) half bridge modules and a magnetic pulse sharpening circuit, which is employed to compress the rising edge of the Marx output pulse. The approach of using multiple small driving transformers, one-turn primary windings of which are in series connection, provides a simple way for gate drive. Coaxial cables are employed as both primary and secondary windings of these transformers for electro-magnetic interference (EMI) shielding. A passive over-current protection measure is adopted so as to promise safe operation of the discharging IGBTs. The experimental
The method of using magnetic switches is proposed to reduce the voltage rise time of the all solid-state pulse source and a generator is constructed. This generator consists of a Marx modulator based on isolated gate bipolar thyristor (IGBT) half bridge modules and a magnetic pulse sharpening circuit, which is employed to compress the rising edge of the Marx output pulse. The approach of using multiple small driving transformers, one-turn primary windings of which are in series connection, provides a simple way for gate drive. Coaxial cables are employed as both primary and secondary windings of these transformers for electro-magnetic interference (EMI) shielding. A passive over-current protection measure is adopted so as to promise safe operation of the discharging IGBTs. The experimental
2010,
22.
Abstract:
A novel inductive energy storage pulsed power source design has been presented, with two energy storage coils separated by a water transmission line. Considering the transmission line as a capacitor, the novel principle circuit was simplified and the discharging formula of the inductor was derived. The formula shows that, the novel technology changes the traditional pure exponentially-decayed discharging waveform into a combination of an exponentially-decayed discharging waveform and a sinusoidally-damped oscillation discharging waveform, which can improve the output waveform and increase the energy conversion efficiency. Based on this theory, experiments have been carried out and an electron beam with a voltage of 300 kV and a current of 20 kA was generated. Several hundreds megawatt micr
A novel inductive energy storage pulsed power source design has been presented, with two energy storage coils separated by a water transmission line. Considering the transmission line as a capacitor, the novel principle circuit was simplified and the discharging formula of the inductor was derived. The formula shows that, the novel technology changes the traditional pure exponentially-decayed discharging waveform into a combination of an exponentially-decayed discharging waveform and a sinusoidally-damped oscillation discharging waveform, which can improve the output waveform and increase the energy conversion efficiency. Based on this theory, experiments have been carried out and an electron beam with a voltage of 300 kV and a current of 20 kA was generated. Several hundreds megawatt micr
2010,
22.
Abstract:
A test circuit was designed and built, which is based on one-stage and two-stage magnetic pulse compression systems without external demagnetization circuits, so as to test the dynamic magnetic characteristic of Ni-Zn ferrite magnetic core under excitation pulses of microsecond and sub-microsecond level. The hysteresis loop of the magnetic core was calculated by tested voltage and current from the magnetic switch, with which various characteristic parameters of the magnetic core under the two kinds of excitation pulses can be easily gained, including saturated magnetic induction intensity, residual magnetic flux density, square ratio, magnetic flux density variation, coercive force, saturated magnetic-field intensity and magnetic hysteresis loss of unit material volume. The comparison of t
A test circuit was designed and built, which is based on one-stage and two-stage magnetic pulse compression systems without external demagnetization circuits, so as to test the dynamic magnetic characteristic of Ni-Zn ferrite magnetic core under excitation pulses of microsecond and sub-microsecond level. The hysteresis loop of the magnetic core was calculated by tested voltage and current from the magnetic switch, with which various characteristic parameters of the magnetic core under the two kinds of excitation pulses can be easily gained, including saturated magnetic induction intensity, residual magnetic flux density, square ratio, magnetic flux density variation, coercive force, saturated magnetic-field intensity and magnetic hysteresis loss of unit material volume. The comparison of t
2010,
22.
Abstract:
The structure of plate-to-cone transition in vacuum transmission line is often used in the multi-modules Z-pinch drivers. This kind of transition will possibly result in an unacceptable power flow loss, particularly, when the transfer angle becomes bigger. In this paper, leaving out the invalidation of magnetically insulation and the loss in the dielectric, the finite difference method is adopted to simulate how variation of the transfer angle affects the power flow. The primary calculation and analysis show that the reflection caused by unmatched impedance will decrease the transmission efficiency with the increase of the transfer angle. The fast rise pulses will be distorted seriously in this structure, while the slow rise pulse will be hardly disturbed. It is favorable for effective pul
The structure of plate-to-cone transition in vacuum transmission line is often used in the multi-modules Z-pinch drivers. This kind of transition will possibly result in an unacceptable power flow loss, particularly, when the transfer angle becomes bigger. In this paper, leaving out the invalidation of magnetically insulation and the loss in the dielectric, the finite difference method is adopted to simulate how variation of the transfer angle affects the power flow. The primary calculation and analysis show that the reflection caused by unmatched impedance will decrease the transmission efficiency with the increase of the transfer angle. The fast rise pulses will be distorted seriously in this structure, while the slow rise pulse will be hardly disturbed. It is favorable for effective pul
2010,
22.
Abstract:
This paper describes a circuit of Marx generator, and compares it with the conventional layout by simulation and experiment. The result indicates that the designed circuit can maintain the voltage between the latter stage switches during the discharging phase of Marx generator, which makes sure the latter stage switches can breakdown reliably and further leads to a small time jitter. A Marx generator used in the linear induction accelerator has been designed and constructed based on this circuit. Its maximal energy storage is 16.87 kJ, and the maximal output voltage is 450 kV. By using low jitter spark gap switches and charged with positive and negative polarities, the Marx generator can operate with subnanosecond jitter.
This paper describes a circuit of Marx generator, and compares it with the conventional layout by simulation and experiment. The result indicates that the designed circuit can maintain the voltage between the latter stage switches during the discharging phase of Marx generator, which makes sure the latter stage switches can breakdown reliably and further leads to a small time jitter. A Marx generator used in the linear induction accelerator has been designed and constructed based on this circuit. Its maximal energy storage is 16.87 kJ, and the maximal output voltage is 450 kV. By using low jitter spark gap switches and charged with positive and negative polarities, the Marx generator can operate with subnanosecond jitter.
2010,
22.
Abstract:
A repetitive pulsed magnetic fields serving as the guiding magnetic field for the repetitive high-power microwave source has been proposed, which makes the source compact with low loss and small heat. A primary energy source for solenoid which can output rep-rate pulsing magnetic field is developed. It adopts half-bridge topology with series resonant constant-current charging technology and the output is adjustable, from 0 to 2.5 kW. The average power can reach 5 kW at most. Without adding other resonant components, the circuit makes full use of the transformer leakage inductance and bridge-arm capacitance so as to reduce the influences of the transformer parameter. The operating process of the circuit is analyzed briefly. The parameters of the power supply are calculated and a designed ex
A repetitive pulsed magnetic fields serving as the guiding magnetic field for the repetitive high-power microwave source has been proposed, which makes the source compact with low loss and small heat. A primary energy source for solenoid which can output rep-rate pulsing magnetic field is developed. It adopts half-bridge topology with series resonant constant-current charging technology and the output is adjustable, from 0 to 2.5 kW. The average power can reach 5 kW at most. Without adding other resonant components, the circuit makes full use of the transformer leakage inductance and bridge-arm capacitance so as to reduce the influences of the transformer parameter. The operating process of the circuit is analyzed briefly. The parameters of the power supply are calculated and a designed ex
2010,
22.
Abstract:
A solid state modulator with peak output power up to several MW is introduced in this paper. This kind modulator is characterized by repetitive frequency and easily-adjustable width of the output pulse for utilization in solid state switch. Storage capacitors of the modulator are charged by HF-inverter charging power supply in constant current mode. A step-up multi-primary winding transformer is applied to decreasing each exciting unit’s operation voltage and current, which could avoid circuit complexities caused by solid state devices connecting in series or parallel. RL pulse compensating network is introduced to counteract top-droop caused by pulse transformer or low capacitance of storage capacitors. With above methods, A magnetron modulator with a peak output voltage of 48 kV, a puls
A solid state modulator with peak output power up to several MW is introduced in this paper. This kind modulator is characterized by repetitive frequency and easily-adjustable width of the output pulse for utilization in solid state switch. Storage capacitors of the modulator are charged by HF-inverter charging power supply in constant current mode. A step-up multi-primary winding transformer is applied to decreasing each exciting unit’s operation voltage and current, which could avoid circuit complexities caused by solid state devices connecting in series or parallel. RL pulse compensating network is introduced to counteract top-droop caused by pulse transformer or low capacitance of storage capacitors. With above methods, A magnetron modulator with a peak output voltage of 48 kV, a puls
2010,
22.
Abstract:
This paper discusses the setup feature of the transmission line transformers (TLT). The theoretic analysis and experimental research of TLT are presented. The technique that many transmission lines can commingle multi-channel narrow pulses to synthesize power is proved by the experiment that a pulse is obtained by 4 channel of pulses with 4.5 kV(50 Ω) each inputting the TLT setup. A compact high voltage narrow pulse generator is designed, a 46 kV(50 Ω) pulse is obtained by the TLT setup synthesizing 36 channel pulses with 8 kV(50 Ω) each. Suggestions for improving pulse waveforms when the technique is used are put forward.
This paper discusses the setup feature of the transmission line transformers (TLT). The theoretic analysis and experimental research of TLT are presented. The technique that many transmission lines can commingle multi-channel narrow pulses to synthesize power is proved by the experiment that a pulse is obtained by 4 channel of pulses with 4.5 kV(50 Ω) each inputting the TLT setup. A compact high voltage narrow pulse generator is designed, a 46 kV(50 Ω) pulse is obtained by the TLT setup synthesizing 36 channel pulses with 8 kV(50 Ω) each. Suggestions for improving pulse waveforms when the technique is used are put forward.
2010,
22.
Abstract:
Capacitors are important storage components in pulsed power equipment. In order to reinforce the reliability of power source equipment, this paper studies how to increase the lifetime of the metallized film pulsed capacitor from the following aspects: electrode structure, heat treatment and working electric field intensity. The results show that the temperature of heat treatment is defined by considering the shrink of polypropylene (PP) film and the thickness of electrode. For different sheet resistance, the temperature of heat treatment has an optimal value, when the self-healing energy is minimal and the lifetime is longest for the capacitor. For different electric field intensity, it should be considered that there was tradeoff between partial discharge at the edge of electrode and capa
Capacitors are important storage components in pulsed power equipment. In order to reinforce the reliability of power source equipment, this paper studies how to increase the lifetime of the metallized film pulsed capacitor from the following aspects: electrode structure, heat treatment and working electric field intensity. The results show that the temperature of heat treatment is defined by considering the shrink of polypropylene (PP) film and the thickness of electrode. For different sheet resistance, the temperature of heat treatment has an optimal value, when the self-healing energy is minimal and the lifetime is longest for the capacitor. For different electric field intensity, it should be considered that there was tradeoff between partial discharge at the edge of electrode and capa
2010,
22.
Abstract:
The design and analysis method of PTS vacuum insulator stack are presented. The voltage waveforms of each-level are obtained by full circuit simulation. The shapes of the components (grading rings, insulator rings, anode and cathode conductors) in each level and the design of the water and MITLs interfaces, were optimized by the electrostatic analysis code. The 3-D and 2-D voltage variation of each insulator of level-A is compared, and the difference is neglectable. The time-dependent performance of insulator stack was evaluated using 2-D PIC code. The voltage variation change caused by electron emission on vacuum side of grading rings is serious, and can greatly affect the whole stack flashover probability.
The design and analysis method of PTS vacuum insulator stack are presented. The voltage waveforms of each-level are obtained by full circuit simulation. The shapes of the components (grading rings, insulator rings, anode and cathode conductors) in each level and the design of the water and MITLs interfaces, were optimized by the electrostatic analysis code. The 3-D and 2-D voltage variation of each insulator of level-A is compared, and the difference is neglectable. The time-dependent performance of insulator stack was evaluated using 2-D PIC code. The voltage variation change caused by electron emission on vacuum side of grading rings is serious, and can greatly affect the whole stack flashover probability.
2010,
22.
Abstract:
With the aid of the circuit code BCYSSYS, a series of small two-staged explosive magnetic generators and a compact explosive pulsed power source(EPPS) have been designed and tested. Experimental results show that the small two-staged generator can output 100 kA currents on an inductive load of 3 μH with the pulse duration of 10 μs. The compact EPPS is shorter than 1.2 m in length, 0.4 m in diameter, and weights 100 kg. When the resistance load is 8.7 Ω, the output power of the EPPS exceeds 20 GW. The calculated and experimental results agree well, verifying the feasibility of theoretical EPPS designing based on BCYSSYS.
With the aid of the circuit code BCYSSYS, a series of small two-staged explosive magnetic generators and a compact explosive pulsed power source(EPPS) have been designed and tested. Experimental results show that the small two-staged generator can output 100 kA currents on an inductive load of 3 μH with the pulse duration of 10 μs. The compact EPPS is shorter than 1.2 m in length, 0.4 m in diameter, and weights 100 kg. When the resistance load is 8.7 Ω, the output power of the EPPS exceeds 20 GW. The calculated and experimental results agree well, verifying the feasibility of theoretical EPPS designing based on BCYSSYS.
2010,
22.
Abstract:
In this paper semi-insulating GaAs photoconductive semiconductor switch(PCSS) and SiC PCSS were fabricated. Triggered by laser pulse at a wavelength of 1 064 nm, photoconductivity tests of the PCSSs were performed at different bias voltages. Dark current-voltage characteristics of GaAs PCSS and the absorption depth of GaAs with different wavelength were obtained experimentally. GaAs PCSSs both in linear mode and nonlinear mode were studied, and peculiar photoconductivity of high-power GaAs PCSS in nonlinear mode was discussed. High-power SiC PCSSs employing extrinsic photoconductivity are under development, and initial experimental results are presented in this paper.
In this paper semi-insulating GaAs photoconductive semiconductor switch(PCSS) and SiC PCSS were fabricated. Triggered by laser pulse at a wavelength of 1 064 nm, photoconductivity tests of the PCSSs were performed at different bias voltages. Dark current-voltage characteristics of GaAs PCSS and the absorption depth of GaAs with different wavelength were obtained experimentally. GaAs PCSSs both in linear mode and nonlinear mode were studied, and peculiar photoconductivity of high-power GaAs PCSS in nonlinear mode was discussed. High-power SiC PCSSs employing extrinsic photoconductivity are under development, and initial experimental results are presented in this paper.
2010,
22.
Abstract:
Photoconductive semiconductor switch(PCSS) with a gap of 18 mm was fabricated from semi-insulating GaAs. Lifetime tests of the PCSS were performed at different repetition rate. Accumulation and dissipation of heat in the switch’s running process was analyzed with the test results. Heat accumulation has an important effect on the lifetime of the switch. When the accumulation power of heat is higher than the dissipation power of heat, the temperature of the chip rises and the resistence reduces. As a results, the leak current increased as high as the charge current of the capacitor and the switch can’t sustain a bias voltage, and the photocurrent decreases as the switch is running. In addition, the damage at the ohm contact is also a heat damage because of a high field at the electrode reg
Photoconductive semiconductor switch(PCSS) with a gap of 18 mm was fabricated from semi-insulating GaAs. Lifetime tests of the PCSS were performed at different repetition rate. Accumulation and dissipation of heat in the switch’s running process was analyzed with the test results. Heat accumulation has an important effect on the lifetime of the switch. When the accumulation power of heat is higher than the dissipation power of heat, the temperature of the chip rises and the resistence reduces. As a results, the leak current increased as high as the charge current of the capacitor and the switch can’t sustain a bias voltage, and the photocurrent decreases as the switch is running. In addition, the damage at the ohm contact is also a heat damage because of a high field at the electrode reg
2010,
22.
Abstract:
The high-coulomb two-electrode coaxial spark gap switch should be one of the better switching solutions in the power conditioning system for high power lasers. The turn-on process of this spark gap switch is studied with software ATP and PSCAD. The influences of several parameters on the turn-on characteristics are simulated and analysed, and then an electrical parameter model of the turn-on process is proposed. Based on this model, the relation between trigger voltage and turn-on energy is obtained in the resulting curve, which shows that trigger energy does not significantly affect the turn on of this switch.
The high-coulomb two-electrode coaxial spark gap switch should be one of the better switching solutions in the power conditioning system for high power lasers. The turn-on process of this spark gap switch is studied with software ATP and PSCAD. The influences of several parameters on the turn-on characteristics are simulated and analysed, and then an electrical parameter model of the turn-on process is proposed. Based on this model, the relation between trigger voltage and turn-on energy is obtained in the resulting curve, which shows that trigger energy does not significantly affect the turn on of this switch.
2010,
22.
Abstract:
In HL80 constant current source, a closed-loop negative feedback and real time serial linear adjustion circuit is adopted for the control of the output current. Triphase AC voltage-modulation module is used to modulate the primary voltage of the transformer. The combination of PLC and touch-screen actualize the graphical interactive operation interface. The communication and control in HL80 is based on ethernet networks. As the load is changed from 2.0 to 3.0 Ω and the output current is changed from 20 A to 80 A, the voltage drop of the modulation transistor is controlled as 8 V±2 V, the precision of the output current is better than 0.12%, the ripple factor is lower than 0.11%. HL80 has been tested more than 10 000 shots without failure.
In HL80 constant current source, a closed-loop negative feedback and real time serial linear adjustion circuit is adopted for the control of the output current. Triphase AC voltage-modulation module is used to modulate the primary voltage of the transformer. The combination of PLC and touch-screen actualize the graphical interactive operation interface. The communication and control in HL80 is based on ethernet networks. As the load is changed from 2.0 to 3.0 Ω and the output current is changed from 20 A to 80 A, the voltage drop of the modulation transistor is controlled as 8 V±2 V, the precision of the output current is better than 0.12%, the ripple factor is lower than 0.11%. HL80 has been tested more than 10 000 shots without failure.
2010,
22.
Abstract:
In order to research the generation technology of electron beams with long pulse and strong current, a high voltage long pulse generator has been designed. The generator contains six parts: Marx generator, charging inductance, pulse-forming line, high voltage switch, pulse transmission line and plane diode. The inner conductor of the pulse-forming line is spiral line, and the working material is deionized water. The indexes of this generator are output voltage 500 kV, current 40 kA, pulse width 1 μs and single pulse energy 20 kJ. The paper mainly introduces the structure and electric parameters of the long pulse generator, and discussies the issues which should be noticed in the designs. At present, the generator is under process.
In order to research the generation technology of electron beams with long pulse and strong current, a high voltage long pulse generator has been designed. The generator contains six parts: Marx generator, charging inductance, pulse-forming line, high voltage switch, pulse transmission line and plane diode. The inner conductor of the pulse-forming line is spiral line, and the working material is deionized water. The indexes of this generator are output voltage 500 kV, current 40 kA, pulse width 1 μs and single pulse energy 20 kJ. The paper mainly introduces the structure and electric parameters of the long pulse generator, and discussies the issues which should be noticed in the designs. At present, the generator is under process.
2010,
22.
Abstract:
For switch delay of normal distribution, the effects of switch jitter and single waveform’s rise time on the rise time of resultant waveforms are discussed when multiple switches work synchronously. The simulation result shows that the effects of switch jitter on the rise time of resultant waveforms are related to the single waveform’s rise time. The less the rise time of single waveform is, the stronger the effects of switch jitter on the rise time of resultant waveforms. For four switches with the jitter of 5 ns, the rise time of resultant waveforms will decrease from 6.7 ns to 1.7 ns when the rise time of single waveform increases from 10 ns to 80 ns. When the rise time of single waveform is large, there is no use going for small switch jitter.
For switch delay of normal distribution, the effects of switch jitter and single waveform’s rise time on the rise time of resultant waveforms are discussed when multiple switches work synchronously. The simulation result shows that the effects of switch jitter on the rise time of resultant waveforms are related to the single waveform’s rise time. The less the rise time of single waveform is, the stronger the effects of switch jitter on the rise time of resultant waveforms. For four switches with the jitter of 5 ns, the rise time of resultant waveforms will decrease from 6.7 ns to 1.7 ns when the rise time of single waveform increases from 10 ns to 80 ns. When the rise time of single waveform is large, there is no use going for small switch jitter.
2010,
22.
Abstract:
Development of 40 GW repetitive pulsed driver is summarized in this report. The output of the 40 GW repetitive pulsed driver source is aimed to exceed 40 GW, the pulse width is about 60ns, and the range of repetition rate is set from 1 pps to 50 pps. Based on the Tesla technology, the general design of the 40 GW driver source is described. The accelerator was assembled and an experiment was performed for generating high power microwave. For charging the forming line, a Tesla transformer with open magnetic core was used, a high efficiency about 70% of the transformer was achieved by means of optimization. As an electron beam source, the output of the 40 GW driver source is more than 40 GW. With 50 Hz repetition rate, the mean power of the diode has exceeded 20 GW. Operation experiments have
Development of 40 GW repetitive pulsed driver is summarized in this report. The output of the 40 GW repetitive pulsed driver source is aimed to exceed 40 GW, the pulse width is about 60ns, and the range of repetition rate is set from 1 pps to 50 pps. Based on the Tesla technology, the general design of the 40 GW driver source is described. The accelerator was assembled and an experiment was performed for generating high power microwave. For charging the forming line, a Tesla transformer with open magnetic core was used, a high efficiency about 70% of the transformer was achieved by means of optimization. As an electron beam source, the output of the 40 GW driver source is more than 40 GW. With 50 Hz repetition rate, the mean power of the diode has exceeded 20 GW. Operation experiments have
2010,
22.
Abstract:
Synchronization characteristics of the cold cathode TPI1-10k/50 thyratron were investigated, through adjusting the hydrogen heater voltage, direct preionization current, pulse preionization current and trigger current. The thyraton can work under 40 kV voltage,16 kA current, 200 ns pulse width and 20 Hz frequency with a jitter of about 2 ns. And the experiment shows that, though adjusting the trigger parameters, the delay can be adjusted by ±1 ns in 40 ns range.
Synchronization characteristics of the cold cathode TPI1-10k/50 thyratron were investigated, through adjusting the hydrogen heater voltage, direct preionization current, pulse preionization current and trigger current. The thyraton can work under 40 kV voltage,16 kA current, 200 ns pulse width and 20 Hz frequency with a jitter of about 2 ns. And the experiment shows that, though adjusting the trigger parameters, the delay can be adjusted by ±1 ns in 40 ns range.
2010,
22.
Abstract:
The merits of the full-solid-state pulser, based on avalanche transistor, are high stability, narrow pulse and short rise-time. But the disadvantage of this pulser is that its output power is low, thus Marx circuit is used to improve the peak-voltage. In this paper, the effect factors of the time-stability and shape-stability are analyzed, some optimizing measures are used to improve the stability, and a high-stability pulser is designed. The pulser’s peak voltage is 2 000 V, pulse width is 5 ns, repetition frequency is higher than 25 kHz, and the pulse width jitter is less than 1% and the peak voltage jitter is less than 1%.
The merits of the full-solid-state pulser, based on avalanche transistor, are high stability, narrow pulse and short rise-time. But the disadvantage of this pulser is that its output power is low, thus Marx circuit is used to improve the peak-voltage. In this paper, the effect factors of the time-stability and shape-stability are analyzed, some optimizing measures are used to improve the stability, and a high-stability pulser is designed. The pulser’s peak voltage is 2 000 V, pulse width is 5 ns, repetition frequency is higher than 25 kHz, and the pulse width jitter is less than 1% and the peak voltage jitter is less than 1%.
2010,
22.
Abstract:
Based on the hundreds kJ Marx generator, an experimental project is designed to study generator’s building time and jitter. The relations between Marx generator’s building time and jitter, the typical row’s building time and jitter, and the relations of switch operation voltage coefficient are studied. The experimental results are as follows: The generator’s first row’s building time ratios the generator’s building time up to 60%. The first two rows building time ratios generator’s building time up to 73%. Marx generator’s building time jitter is mainly the first row’s jitter. The first row’s building time jitter is mainly from the breakdown delay time jitter of four parallel gas spark switches. Finally, according to the results of experiment, main influencing factors are accordi
Based on the hundreds kJ Marx generator, an experimental project is designed to study generator’s building time and jitter. The relations between Marx generator’s building time and jitter, the typical row’s building time and jitter, and the relations of switch operation voltage coefficient are studied. The experimental results are as follows: The generator’s first row’s building time ratios the generator’s building time up to 60%. The first two rows building time ratios generator’s building time up to 73%. Marx generator’s building time jitter is mainly the first row’s jitter. The first row’s building time jitter is mainly from the breakdown delay time jitter of four parallel gas spark switches. Finally, according to the results of experiment, main influencing factors are accordi
2010,
22.
Abstract:
The structure and working principle of reversely switched dynistor(RSD) semiconductor closing switch are introduced. Design techniques of the high voltage RSD assembly are analyzed. A 12 kV RSD assembly and its trigger system have been designed and constructed, which can operate at 10~12 kV. Test results show the stable and reliable operation of this assembly. Under 12 kV, the peak amplitude of current could reach 133 kA, with 24 C charge transferred and current rising rate of 4.12 kA/μs, and the peak power switched could reach 1.6 GW．
The structure and working principle of reversely switched dynistor(RSD) semiconductor closing switch are introduced. Design techniques of the high voltage RSD assembly are analyzed. A 12 kV RSD assembly and its trigger system have been designed and constructed, which can operate at 10~12 kV. Test results show the stable and reliable operation of this assembly. Under 12 kV, the peak amplitude of current could reach 133 kA, with 24 C charge transferred and current rising rate of 4.12 kA/μs, and the peak power switched could reach 1.6 GW．
2010,
22.
Abstract:
The emittance of multi-pulsed electron beams was experimentally measured using pepper pot and thus the corresponding brightness was calculated. Different from using fluorescent screen as the recorder of beam divergence angle, a quartz foil was used to record the information through Cerenkov radiation, which is generated by the interaction of electron beamlets and the quartz foil. The phenomenon of beam rotation in magnetic field was observed in the experiment, and the integrated brightness of double-pulsed and four-pulsed beams were measured. For the electron beam of about 600 kV, the divergence of beamlets was below 2° when the magnetic field at the pepper plate was lower than 2.7 mT. The calculated brightnesses of the double-pulsed and four-pulsed beams were 4.14×108 A/(m·rad)2 and 7.
The emittance of multi-pulsed electron beams was experimentally measured using pepper pot and thus the corresponding brightness was calculated. Different from using fluorescent screen as the recorder of beam divergence angle, a quartz foil was used to record the information through Cerenkov radiation, which is generated by the interaction of electron beamlets and the quartz foil. The phenomenon of beam rotation in magnetic field was observed in the experiment, and the integrated brightness of double-pulsed and four-pulsed beams were measured. For the electron beam of about 600 kV, the divergence of beamlets was below 2° when the magnetic field at the pepper plate was lower than 2.7 mT. The calculated brightnesses of the double-pulsed and four-pulsed beams were 4.14×108 A/(m·rad)2 and 7.
2010,
22.
Abstract:
Take the Dragon-Ⅰ accelerator as an example, the structure response under strong vibration has been calculated using time history analysis method for the large scale accelerator, and the offsets of key points on the accelerator were measured. Numerical results show that there is 2 mm deformation in the middle of the accelerator, and in this segment the measured alignment offset is about 0.6 mm, and the measured displacement is about 2 mm. Based on the analysis of numerical calculation and measurement, the linear deviation of mechanical axis is less than ±0.2 mm after alignment. The analysis show that the calculation results can provide references for measuring point arrangement, on-site inspection and measurement data analysis.
Take the Dragon-Ⅰ accelerator as an example, the structure response under strong vibration has been calculated using time history analysis method for the large scale accelerator, and the offsets of key points on the accelerator were measured. Numerical results show that there is 2 mm deformation in the middle of the accelerator, and in this segment the measured alignment offset is about 0.6 mm, and the measured displacement is about 2 mm. Based on the analysis of numerical calculation and measurement, the linear deviation of mechanical axis is less than ±0.2 mm after alignment. The analysis show that the calculation results can provide references for measuring point arrangement, on-site inspection and measurement data analysis.
2010,
22.
Abstract:
The potential energy expression of cylindrically symmetric intense electron beams is derived and the differential equation of RMS emittance is presented in this paper. The decrease of beam potential energy which is leaded by change of charged particle density distribution during the transportation brings the growth of RMS emittance. The change of the charged particle density distribution is always toward to decreasing the potential energy, such as the growth of the emittance. Furthermore, based on the basic definition of emttance, different model transverse motions including beam envelope oscillation with no influence on emittance and ruleless thermal motion with influence on emittance are expatiated. Several factors of influencing beam emittance are discussed respectively and some method
The potential energy expression of cylindrically symmetric intense electron beams is derived and the differential equation of RMS emittance is presented in this paper. The decrease of beam potential energy which is leaded by change of charged particle density distribution during the transportation brings the growth of RMS emittance. The change of the charged particle density distribution is always toward to decreasing the potential energy, such as the growth of the emittance. Furthermore, based on the basic definition of emttance, different model transverse motions including beam envelope oscillation with no influence on emittance and ruleless thermal motion with influence on emittance are expatiated. Several factors of influencing beam emittance are discussed respectively and some method
2010,
22.
Abstract:
This paper presents the research on temperature measurement of solenoid loop. The measuring temperature fiber is layered in solenoid loop for the accelerator cell. When the solenoid loop is supplied with high current form a constant current source, its temperature increases rapidly. The temperature fiber can measure the temperature of the solenoid loop and get temperature measurement rule. Experiment and simulation show temperature of interior solenoid loop the highest and it decreases from the interior to the exterior of solenoid loop. To control temperature of solenoid loop under 60 ℃, simulation displays load interval of constant current source with 80 A current should be at least is 17.5 minutes.
This paper presents the research on temperature measurement of solenoid loop. The measuring temperature fiber is layered in solenoid loop for the accelerator cell. When the solenoid loop is supplied with high current form a constant current source, its temperature increases rapidly. The temperature fiber can measure the temperature of the solenoid loop and get temperature measurement rule. Experiment and simulation show temperature of interior solenoid loop the highest and it decreases from the interior to the exterior of solenoid loop. To control temperature of solenoid loop under 60 ℃, simulation displays load interval of constant current source with 80 A current should be at least is 17.5 minutes.
2010,
22.
Abstract:
This paper describes the research progress of manufacturing technology for amorphous cores, including layer insulation, magnetic field annealing and encapsulation technology. The results show as follows: (1) for the amorphous ribbon surface is coated with 0.6~1.0 μm thick SiO2 insulation, the breakdown voltage is no less than 120 V DC between ribbon layers; (2) through magnetic field annealing, the remanence ratio is larger than 0.90 or less than 0.20 for longitudinal or latitudinal field, respectively, and the amorphous core magnetic property varies within 5% after encapsulation. Through experiments on big amorphous cores with layer insulation under fast-pulsed condition, the pulsed permeability and flux swing were obtained. The flux swing of the Fe-based amorphous core of 1 0
This paper describes the research progress of manufacturing technology for amorphous cores, including layer insulation, magnetic field annealing and encapsulation technology. The results show as follows: (1) for the amorphous ribbon surface is coated with 0.6~1.0 μm thick SiO2 insulation, the breakdown voltage is no less than 120 V DC between ribbon layers; (2) through magnetic field annealing, the remanence ratio is larger than 0.90 or less than 0.20 for longitudinal or latitudinal field, respectively, and the amorphous core magnetic property varies within 5% after encapsulation. Through experiments on big amorphous cores with layer insulation under fast-pulsed condition, the pulsed permeability and flux swing were obtained. The flux swing of the Fe-based amorphous core of 1 0
2010,
22.
Abstract:
This paper reports the experiment of a Ka-band relative backward wave oscillator(RBWO) driven by the all-solid-state pulsed power generator based on semiconductor opening switch. Under working voltage of 200～360 kV and current of 2.6 kA, the generator’s output is about 20 ns in pulse width with rise time less than 9 ns. The experiment show that Ka-band RBWO can generate microwaves with peak power about 50 MW, frequency 36～38 GHz, pulse width about 10 ns, and repetition rate 10 Hz。
This paper reports the experiment of a Ka-band relative backward wave oscillator(RBWO) driven by the all-solid-state pulsed power generator based on semiconductor opening switch. Under working voltage of 200～360 kV and current of 2.6 kA, the generator’s output is about 20 ns in pulse width with rise time less than 9 ns. The experiment show that Ka-band RBWO can generate microwaves with peak power about 50 MW, frequency 36～38 GHz, pulse width about 10 ns, and repetition rate 10 Hz。
2010,
22.
Abstract:
Designed through research of electron beam transmission characteristic in different coupled cavity structures, long periodic permanent magnetic focusing system solves problems of factors influencing electron trajectories such as transverse magnetic field, open magnetic ring and magnetic field in transition region. 3D program simulation of electron optics system for X-band coupled cavity traveling wave tube shows 100% transfer efficiency of electron beam and 9% ripple of electron beam, which accords with requirements of coupled cavity traveling wave tube experiment.
Designed through research of electron beam transmission characteristic in different coupled cavity structures, long periodic permanent magnetic focusing system solves problems of factors influencing electron trajectories such as transverse magnetic field, open magnetic ring and magnetic field in transition region. 3D program simulation of electron optics system for X-band coupled cavity traveling wave tube shows 100% transfer efficiency of electron beam and 9% ripple of electron beam, which accords with requirements of coupled cavity traveling wave tube experiment.
2010,
22.
Abstract:
An X-band superradiance relativistic backward wave oscillator(RBWO) was designed by particle simulation applying superradiance mechanism, and the devices experimental study was performed on a compact Tesla pulse source. Space power integration and analysis of radiation microwave time-domain signal indicate that microwave pulses of 1.4 GW peak power, 9.36 GHz central frequency, 500~700 ps pulse width, TE11 radiation mode and 100 Hz repetitive pulse frequency were generated with an electron beam of 350 kV voltage, 4.8 kA current and 3.1 ns pulse width and a guiding magnetic field of 2.2 T. The power transfer efficiency exceeds 80%. The experiment results are consistent with the simulation results. The repetitive subnanosecond GW-level microwave was realised successfully under sho
An X-band superradiance relativistic backward wave oscillator(RBWO) was designed by particle simulation applying superradiance mechanism, and the devices experimental study was performed on a compact Tesla pulse source. Space power integration and analysis of radiation microwave time-domain signal indicate that microwave pulses of 1.4 GW peak power, 9.36 GHz central frequency, 500~700 ps pulse width, TE11 radiation mode and 100 Hz repetitive pulse frequency were generated with an electron beam of 350 kV voltage, 4.8 kA current and 3.1 ns pulse width and a guiding magnetic field of 2.2 T. The power transfer efficiency exceeds 80%. The experiment results are consistent with the simulation results. The repetitive subnanosecond GW-level microwave was realised successfully under sho
2010,
22.
Abstract:
In the S-band Stanford linear accelerator center energy doublers (SLED) compression experiment, the SLED was measured in low power and high power, including its parameters, output power and power amplification. In the experiment, the microwave source system was modified and a synchronizing signal generator was developed. The influence of the input power width upon the output power and the RF breakdown in the experiment were also studied. When the input power was 5 MW, a power amplification of 7.122 at 260 ns and a peak power of 35.35 MW were acquired.
In the S-band Stanford linear accelerator center energy doublers (SLED) compression experiment, the SLED was measured in low power and high power, including its parameters, output power and power amplification. In the experiment, the microwave source system was modified and a synchronizing signal generator was developed. The influence of the input power width upon the output power and the RF breakdown in the experiment were also studied. When the input power was 5 MW, a power amplification of 7.122 at 260 ns and a peak power of 35.35 MW were acquired.
2010,
22.
Abstract:
An L-band double ladder cathode magnetically insulated transmission line oscillator(MILO) has been simulated by a 2.5D PIC code. Employing an electron beam of 710 kV, 56.6 kA, a microwave output of 4.8 GW was obtained at 1.22 GHz. Experiment equipment was designed according to the simulation result and an experiment test was carried out on a low impedance accelerator, including the test of microwave frequency, mode and power. The measurement system and methods are introduced, Under the condition of 740 kV diode voltage and 61 kA current, a microwave output power of 3.57 GW was got at 1.23 GHz, corresponding to a power conversion efficiency of 8%. The radiation mode was TM01, and pulse width was 46 ns.
An L-band double ladder cathode magnetically insulated transmission line oscillator(MILO) has been simulated by a 2.5D PIC code. Employing an electron beam of 710 kV, 56.6 kA, a microwave output of 4.8 GW was obtained at 1.22 GHz. Experiment equipment was designed according to the simulation result and an experiment test was carried out on a low impedance accelerator, including the test of microwave frequency, mode and power. The measurement system and methods are introduced, Under the condition of 740 kV diode voltage and 61 kA current, a microwave output power of 3.57 GW was got at 1.23 GHz, corresponding to a power conversion efficiency of 8%. The radiation mode was TM01, and pulse width was 46 ns.
2010,
22.
Abstract:
An inward emitting magnetically insulated transmission line oscillator (MILO) is presented and a method to axially extract microwave is assumed. The inward-emitting MILO has an novel design of structure with outer cathode and inner anode, which can recycle spoke current to provide selfinsulating angular magnetic field, thus to improve the tube’s efficiency. The outer cathode has expanded emitting area, and the current density can be reduced correspondingly for a long cathode life. PIC simulation reveals the relationship between the MILO’s structure parameters and its output power. When the electron beam voltage is 890 kV and beam current is about 56.1 kA, microwave output of 3.6 GW is obtained with frequency of 8.2 GHz．
An inward emitting magnetically insulated transmission line oscillator (MILO) is presented and a method to axially extract microwave is assumed. The inward-emitting MILO has an novel design of structure with outer cathode and inner anode, which can recycle spoke current to provide selfinsulating angular magnetic field, thus to improve the tube’s efficiency. The outer cathode has expanded emitting area, and the current density can be reduced correspondingly for a long cathode life. PIC simulation reveals the relationship between the MILO’s structure parameters and its output power. When the electron beam voltage is 890 kV and beam current is about 56.1 kA, microwave output of 3.6 GW is obtained with frequency of 8.2 GHz．
2010,
22.
Abstract:
The linear dispersion relation of SWSs driven by annular beam with finite magnetic field is obtained. Numerical analysis is carried out according to the experimental parameters. Based on the PIC simulation results obtained by KARAT, elementary experiment was designed and carried out, from which terahertz wave with frequency more than 0.14 THz, pulse duration 1～2 ns and output power more than 100 kW was acquired.
The linear dispersion relation of SWSs driven by annular beam with finite magnetic field is obtained. Numerical analysis is carried out according to the experimental parameters. Based on the PIC simulation results obtained by KARAT, elementary experiment was designed and carried out, from which terahertz wave with frequency more than 0.14 THz, pulse duration 1～2 ns and output power more than 100 kW was acquired.
2010,
22.
Abstract:
A high power microwave experiment is carried out based on TPG2000 pulse power generator and X-band relativistic backward wave oscillator(RBWO) with a resonant reflector. A microwave with a power of about 2.5 GW and a pulse width of about 20 ns is obtained and the pulse shortening phenomenon is observed, which is caused by resonant reflector breakdown and secondary electron emitting. Chamfering is used to decrease the electric field and restrain the electron emitting on the edge of the resonant reflector. The electric field and reflective parameter varying with chamfered radius is analyzed and corresponding experiments have been conducted. The results indicate that the pulse width increases and the efficiency decreases, with chamfered radius increasing. With a 900 kV, 9 kA electron beam and
A high power microwave experiment is carried out based on TPG2000 pulse power generator and X-band relativistic backward wave oscillator(RBWO) with a resonant reflector. A microwave with a power of about 2.5 GW and a pulse width of about 20 ns is obtained and the pulse shortening phenomenon is observed, which is caused by resonant reflector breakdown and secondary electron emitting. Chamfering is used to decrease the electric field and restrain the electron emitting on the edge of the resonant reflector. The electric field and reflective parameter varying with chamfered radius is analyzed and corresponding experiments have been conducted. The results indicate that the pulse width increases and the efficiency decreases, with chamfered radius increasing. With a 900 kV, 9 kA electron beam and
2010,
22.
Abstract:
This paper describes the diagnostics developed in recent years for gas-puff and wire array Z-pinch experiments performed on Yang accelerator (peak current 1.2 MA, rise time 85 ns). An eight-channel Dante spectrometer and a scintillator X-ray power meter were used to measure the radiation power, energy and sub-keV power spectra of soft X-ray. Two crystal spectrometers (elliptically and convex cylindrically curved) were employed to obtain the plasma parameters from the line spectra in keV range. A transmission grating spectrometer was fabricated to measure the soft X-ray spectra in sub-keV range. An X-ray framing camera, a multi-channel grazing incidence pinhole X-ray camera and a laser differential interferometer were used to obtain the image and electron density of the imploding plasmas. T
This paper describes the diagnostics developed in recent years for gas-puff and wire array Z-pinch experiments performed on Yang accelerator (peak current 1.2 MA, rise time 85 ns). An eight-channel Dante spectrometer and a scintillator X-ray power meter were used to measure the radiation power, energy and sub-keV power spectra of soft X-ray. Two crystal spectrometers (elliptically and convex cylindrically curved) were employed to obtain the plasma parameters from the line spectra in keV range. A transmission grating spectrometer was fabricated to measure the soft X-ray spectra in sub-keV range. An X-ray framing camera, a multi-channel grazing incidence pinhole X-ray camera and a laser differential interferometer were used to obtain the image and electron density of the imploding plasmas. T
2010,
22.
Abstract:
The transfer function of the measurement system is established on the lumped parameter model of Rogowski coil, and the optimal damping resistor of the differential type of Rogowski coil is obtained under the steady sine input. In this paper, the amplitude-frequency characteristics of RC integrator circuit and active integrator circuit are compared, and also the actual bandwidths of the two measurement systems are determined by the measurement precision. Using active integrator circuit, the measuring bandwidth is extended and the transient performance is improved. Theoretical analysis indicates that the optimal structure and parameters can inhibit the integrator drift. Therefore, the measuring system has the features of high accuracy and reliability. The experimental results in SG-Ⅲ have p
The transfer function of the measurement system is established on the lumped parameter model of Rogowski coil, and the optimal damping resistor of the differential type of Rogowski coil is obtained under the steady sine input. In this paper, the amplitude-frequency characteristics of RC integrator circuit and active integrator circuit are compared, and also the actual bandwidths of the two measurement systems are determined by the measurement precision. Using active integrator circuit, the measuring bandwidth is extended and the transient performance is improved. Theoretical analysis indicates that the optimal structure and parameters can inhibit the integrator drift. Therefore, the measuring system has the features of high accuracy and reliability. The experimental results in SG-Ⅲ have p
2010,
22.
Abstract:
This paper presents the configuration and measuring parameters of scintillator power meter applied in Z-pinch plasma soft X-ray yield measurement on Yang accelerator. It also introduces the calibration experiment on BSRF, and analyzes the defect of the power meter from calibration results, the possible errors and feasible method for correcting the errors. The measuring results are revised according to spectrum acquired from Dante spectrometer. The revised discrepancy of two instruments is decreased from over 30% to subter-15%. Finally, the result of yield measurement of the puff Z-pinch X-ray radiation is reported as well, i.e., hundreds of Joule, multigigawatt levels of soft X ray radiation were produced by puff Z-pinch on Yang accelerator.
This paper presents the configuration and measuring parameters of scintillator power meter applied in Z-pinch plasma soft X-ray yield measurement on Yang accelerator. It also introduces the calibration experiment on BSRF, and analyzes the defect of the power meter from calibration results, the possible errors and feasible method for correcting the errors. The measuring results are revised according to spectrum acquired from Dante spectrometer. The revised discrepancy of two instruments is decreased from over 30% to subter-15%. Finally, the result of yield measurement of the puff Z-pinch X-ray radiation is reported as well, i.e., hundreds of Joule, multigigawatt levels of soft X ray radiation were produced by puff Z-pinch on Yang accelerator.
2010,
22.
Abstract:
Based on the distributing integral way of high power microwave(HPM) radiation field and the way of attenuation, delaying and combining, an array device for power measurement of HPM was developed. 16 HPM radiation waveforms displayed in one oscillograph and the power density of different position can be attained by this experiment device simultaneously. Under the hypothesis of axially symmetric radiation patterns, the radiation power of single short pulse HPM source may be numerated using compiled language. The device has been applied to the power measurement of X-band BWO HPM source.
Based on the distributing integral way of high power microwave(HPM) radiation field and the way of attenuation, delaying and combining, an array device for power measurement of HPM was developed. 16 HPM radiation waveforms displayed in one oscillograph and the power density of different position can be attained by this experiment device simultaneously. Under the hypothesis of axially symmetric radiation patterns, the radiation power of single short pulse HPM source may be numerated using compiled language. The device has been applied to the power measurement of X-band BWO HPM source.
2010,
22.
Abstract:
The experimental platform of laser-triggered surface flashover in pulsed voltage has been built up in the laboratory, and then the experiment of laser-triggered surface flashover was carried out using nylon columned insulators. On this basis, the laser-triggered surface flashover of nylon was simulated by Monte Carlo method, and the delay time of flashover was obtained with different laser energy densities. The simulation result shows that delay time decreases with laser energy density increasing, indicating an increase of the number of electrons in this process. The trend of simulation and experiment is consistent, verifying the mechanism of laser-triggered flashover.
The experimental platform of laser-triggered surface flashover in pulsed voltage has been built up in the laboratory, and then the experiment of laser-triggered surface flashover was carried out using nylon columned insulators. On this basis, the laser-triggered surface flashover of nylon was simulated by Monte Carlo method, and the delay time of flashover was obtained with different laser energy densities. The simulation result shows that delay time decreases with laser energy density increasing, indicating an increase of the number of electrons in this process. The trend of simulation and experiment is consistent, verifying the mechanism of laser-triggered flashover.
2010,
22.
Abstract:
Systematic study is done on problems of resistance and flux losses in helical magnetic flux compression generator(MFCG) based on current equation and magnetic diffusion equation. The program MFCG-Ⅳ is extended by considering contact resistance model, and Ohmic resistance model based on skin depth and neighboring interaction model. Using the experimental parameters of Texas Tech University (TTU), comparable numerical results with the experimental ones are derived, which can depict the physical phenomena.
Systematic study is done on problems of resistance and flux losses in helical magnetic flux compression generator(MFCG) based on current equation and magnetic diffusion equation. The program MFCG-Ⅳ is extended by considering contact resistance model, and Ohmic resistance model based on skin depth and neighboring interaction model. Using the experimental parameters of Texas Tech University (TTU), comparable numerical results with the experimental ones are derived, which can depict the physical phenomena.
2010,
22.
Abstract:
The PIC-MCC simulation of a laser triggered gas switch (LTGS) with cylindrical electrodes has been conducted with XOOPIC code by adding electron-SF6 collision cross section data. The LTGS works as the main switch of the pre-amplifier of Heaven-Light Ⅰ Laser generator. The paper presents the simulation results of the streamer formation on pre-breakdown stage of the gas switch, show that the initial radius of arc is 250 μm and the time at which the ions reach the cathode is about 0.15 ns. It also outlines the simulation conditions and some necessary assumptions and their effects on simulation results. The PIC-MCC simulation is intended to obtain the initial conditions needed by circuit simulation of the arc resistance and to predict the breakdown time of the gas switch. The simulation prod
The PIC-MCC simulation of a laser triggered gas switch (LTGS) with cylindrical electrodes has been conducted with XOOPIC code by adding electron-SF6 collision cross section data. The LTGS works as the main switch of the pre-amplifier of Heaven-Light Ⅰ Laser generator. The paper presents the simulation results of the streamer formation on pre-breakdown stage of the gas switch, show that the initial radius of arc is 250 μm and the time at which the ions reach the cathode is about 0.15 ns. It also outlines the simulation conditions and some necessary assumptions and their effects on simulation results. The PIC-MCC simulation is intended to obtain the initial conditions needed by circuit simulation of the arc resistance and to predict the breakdown time of the gas switch. The simulation prod
2010,
22.
Abstract:
This paper studies the 3D electromagnetic behavior of solid armature in rail electromagnetic launche r(EML) using finite-element(FE) software ANSYS. A simple quasi-static model for EML, with A-formulation of Maxwell’s equations, is discussed to simulate the three-dimension C-shaped armature. Good agreement to the published simulation data is obtained from EM code EMAP3D, including the current density distribution, magnetic field distribution and Lorentz force in the solid armature for different time. The results indicate that the stationary armature model, based on FE software ANSYS, provide tools for electromagnetic character predictions of rail-armature in electromagnetic launcher.
This paper studies the 3D electromagnetic behavior of solid armature in rail electromagnetic launche r(EML) using finite-element(FE) software ANSYS. A simple quasi-static model for EML, with A-formulation of Maxwell’s equations, is discussed to simulate the three-dimension C-shaped armature. Good agreement to the published simulation data is obtained from EM code EMAP3D, including the current density distribution, magnetic field distribution and Lorentz force in the solid armature for different time. The results indicate that the stationary armature model, based on FE software ANSYS, provide tools for electromagnetic character predictions of rail-armature in electromagnetic launcher.
2010,
22.
Abstract:
To study the beam instability caused by wake field effect, a dielectric wall accelerator module model consisting of asymmetric pulse forming line, micro-stacked insulator and conductor layer was established, the finite integral method was used to simulate the wake field in the accelerating structure of dielectric wan accelerator (DWA) for high-current electron beam, wake potential and wake impedance were calculated for the single and two accelerating units. The results show the wake potential and wake impedance were small in x and y directions, the wake impedance can reach hundreds of ohms in z direction. It is proved that advantageous accelerating cavity length and path continuity, the influence of beam instability is relatively small, the DWA structure the beam transmission requirements
To study the beam instability caused by wake field effect, a dielectric wall accelerator module model consisting of asymmetric pulse forming line, micro-stacked insulator and conductor layer was established, the finite integral method was used to simulate the wake field in the accelerating structure of dielectric wan accelerator (DWA) for high-current electron beam, wake potential and wake impedance were calculated for the single and two accelerating units. The results show the wake potential and wake impedance were small in x and y directions, the wake impedance can reach hundreds of ohms in z direction. It is proved that advantageous accelerating cavity length and path continuity, the influence of beam instability is relatively small, the DWA structure the beam transmission requirements
2010,
22.
Abstract:
Finite-difference time-domain method and particle-in-cell simulation were combined to simulate the beam transport process in linear induction accelerators. The non-uniform grid model was used to fulfill the three-dimensional simulation modeling of the accelerator gap, and electric field was generated at the gap. The magnetic field distribution was calculated with three steps, which was generated by the solenoid mounted inside the accelerating cell. Combining the focusing magnetic field with the acceleration section, the electron beam transport process was simulated and its results were analyzed, proving the validity of this method.
Finite-difference time-domain method and particle-in-cell simulation were combined to simulate the beam transport process in linear induction accelerators. The non-uniform grid model was used to fulfill the three-dimensional simulation modeling of the accelerator gap, and electric field was generated at the gap. The magnetic field distribution was calculated with three steps, which was generated by the solenoid mounted inside the accelerating cell. Combining the focusing magnetic field with the acceleration section, the electron beam transport process was simulated and its results were analyzed, proving the validity of this method.
2010,
22.
Abstract:
The Qiangguang-Ⅰ accelerator is made up of linear transformer driver(LTD), water transmission line, water switch and diode. In this paper, parameters of the LTD, transmission line and water switch were estimated, and circuit models of nonlinear magnetic cores and pulse power drivers were established. In addition, properties of silicon steel magnetic cores were investigated by experiments, the results of which are perfectly in accord with the simulation ones of the LTD module and accelerator. The simulation shows that the magnetic cores was not saturated under current running status. And the output parameters would not alter for the LTD store capacitance changing from 2.8 μF to 4.0 μF with 35 kV charge voltage. These all would establish the basis for the enhancement of energy store and
The Qiangguang-Ⅰ accelerator is made up of linear transformer driver(LTD), water transmission line, water switch and diode. In this paper, parameters of the LTD, transmission line and water switch were estimated, and circuit models of nonlinear magnetic cores and pulse power drivers were established. In addition, properties of silicon steel magnetic cores were investigated by experiments, the results of which are perfectly in accord with the simulation ones of the LTD module and accelerator. The simulation shows that the magnetic cores was not saturated under current running status. And the output parameters would not alter for the LTD store capacitance changing from 2.8 μF to 4.0 μF with 35 kV charge voltage. These all would establish the basis for the enhancement of energy store and
2010,
22.
Abstract:
Graphite slices calorimeter is a traditional device for the energy diagnosis of the relativistic electron beams. The measurement of the electron energy spectrum is simulated through a series of numerical experiments, and a spectrum skipping method is investigated. With an MCNP experiment model, transfer functions between the input electron energy and the deposited energy are established for different electron deposited energy distributions. In addition, a method for solving the transfer functions is proposed, and its reliability is investigated by introducing human disturbances.
Graphite slices calorimeter is a traditional device for the energy diagnosis of the relativistic electron beams. The measurement of the electron energy spectrum is simulated through a series of numerical experiments, and a spectrum skipping method is investigated. With an MCNP experiment model, transfer functions between the input electron energy and the deposited energy are established for different electron deposited energy distributions. In addition, a method for solving the transfer functions is proposed, and its reliability is investigated by introducing human disturbances.
2010,
22.
Abstract:
A pulsed power generator (PPG-Ⅰ) with a voltage of 500 kV in amplitude, a current of 400 kA in amplitude and 100 ns in pulse width was constructed. The development of X-pinches and the early stages of wire-array Z-pinches were investigated by X-ray backlighting using the X-pinch driven by PPG-Ⅰ as X-ray source. The plasma explosion and implosion near the cross point of the X-shaped wires can be clearly seen from a series of backlighting images taken at different time during X-pinch discharge. To study the early behavior of the plasma in wire-array Z-pinches, an X-pinch installed in the place of a current-return rod was used as the X-ray source to backlight a wire-array Z-pinch installed in the center between the anode and the cathode. The plasma formation, the inter-wire plasma merging,
A pulsed power generator (PPG-Ⅰ) with a voltage of 500 kV in amplitude, a current of 400 kA in amplitude and 100 ns in pulse width was constructed. The development of X-pinches and the early stages of wire-array Z-pinches were investigated by X-ray backlighting using the X-pinch driven by PPG-Ⅰ as X-ray source. The plasma explosion and implosion near the cross point of the X-shaped wires can be clearly seen from a series of backlighting images taken at different time during X-pinch discharge. To study the early behavior of the plasma in wire-array Z-pinches, an X-pinch installed in the place of a current-return rod was used as the X-ray source to backlight a wire-array Z-pinch installed in the center between the anode and the cathode. The plasma formation, the inter-wire plasma merging,
2010,
22.
Abstract:
The study of sliding electrical contacts between the rails and the armature is of great importance for a multi-shot railgun. A 10 mm square-bore railgun has been developed for the experimental study, with a pulsed-power supply of a 0.2 MJ capacitor bank. In the multi-shot experiment, a number of aluminum armatures are launched under the same condition with the deposit covering the copper rails not polished. The result indicates that the state of the armature-rail interface in a multi-shot railgun tends to be much better and there is less arc erosion than in a single-shot one. The armature in the latter shot starts to move earlier than in the former, and the muzzle velocity increases with the number of shots. It is concluded that the layer of deposit generated from the former shots, rich in
The study of sliding electrical contacts between the rails and the armature is of great importance for a multi-shot railgun. A 10 mm square-bore railgun has been developed for the experimental study, with a pulsed-power supply of a 0.2 MJ capacitor bank. In the multi-shot experiment, a number of aluminum armatures are launched under the same condition with the deposit covering the copper rails not polished. The result indicates that the state of the armature-rail interface in a multi-shot railgun tends to be much better and there is less arc erosion than in a single-shot one. The armature in the latter shot starts to move earlier than in the former, and the muzzle velocity increases with the number of shots. It is concluded that the layer of deposit generated from the former shots, rich in
2010,
22.
Abstract:
Preliminary investigation about the insulating property diversity of the insulation materials, including nylon and cross-linked polystyrene, under monopulse and triplepulse was done on the Multiple Pulse Platform. The ensemble averages of flashover strength of the two materials under different electric tension were obtained. Preliminary analysis of the experimental result, was given considering the experimental phenomena. The study provides a basis for the design of new insulation device.
Preliminary investigation about the insulating property diversity of the insulation materials, including nylon and cross-linked polystyrene, under monopulse and triplepulse was done on the Multiple Pulse Platform. The ensemble averages of flashover strength of the two materials under different electric tension were obtained. Preliminary analysis of the experimental result, was given considering the experimental phenomena. The study provides a basis for the design of new insulation device.
2010,
22.
Abstract:
A 150 kV pulsed X-ray system designed according to the bipolar charged Marx generator was introduced. Low jitter electric field-distortion switches, low inductance solidstate resistors and ceramic capacitors were used in the pulse generator to shorten the pulse risetime and width. The Marx generator was connected to the X-ray tube through the high-voltage cable. Then it can output a pulse with 100～150 kV amplitude, and drive the X-ray tube to produce a flash X-ray with 90.3×10-7 C/kg dose and 70 ns pulse width at 0.25 m. The X-ray system is easy to operate with stable performance and compact structure．
A 150 kV pulsed X-ray system designed according to the bipolar charged Marx generator was introduced. Low jitter electric field-distortion switches, low inductance solidstate resistors and ceramic capacitors were used in the pulse generator to shorten the pulse risetime and width. The Marx generator was connected to the X-ray tube through the high-voltage cable. Then it can output a pulse with 100～150 kV amplitude, and drive the X-ray tube to produce a flash X-ray with 90.3×10-7 C/kg dose and 70 ns pulse width at 0.25 m. The X-ray system is easy to operate with stable performance and compact structure．
2010,
22.
Abstract:
The pulsed X-ray source based on the inductive voltage adder (IVA) and rod pinch diode (RPD) is developed, and its configuration and main parts and output parameters are introduced in detail. The Marx generator with 3.3 MV charges the water pulsed forming lines with 7.8 Ω and produces the high power pulse of 70 ns width with about 1 MV feeding the three IVA cells in parallel through the peaking water switch and the pre-pulse oil switch. The secondary of IVA adopts the vacuum insulation transmission line (VITL) with the impedance from 40 Ω up to 60 Ω, driving the RPD isolated from the output terminal of IVA for 2 m VITL. The diameter of the graphite cathode of RPD is 12 mm, and the diameter of the tungsten anode rod is 1.2 mm. The electron beam from the cathode is pinched to the tip of t
The pulsed X-ray source based on the inductive voltage adder (IVA) and rod pinch diode (RPD) is developed, and its configuration and main parts and output parameters are introduced in detail. The Marx generator with 3.3 MV charges the water pulsed forming lines with 7.8 Ω and produces the high power pulse of 70 ns width with about 1 MV feeding the three IVA cells in parallel through the peaking water switch and the pre-pulse oil switch. The secondary of IVA adopts the vacuum insulation transmission line (VITL) with the impedance from 40 Ω up to 60 Ω, driving the RPD isolated from the output terminal of IVA for 2 m VITL. The diameter of the graphite cathode of RPD is 12 mm, and the diameter of the tungsten anode rod is 1.2 mm. The electron beam from the cathode is pinched to the tip of t
