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RSS2003 Vol. 15, No. 05
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2003,
15.
Abstract:
After briefly analyzing the technical difficulties of diagnosing high fluence electron beam，three new methods for diagnosing parameters, including filtered Farady cup for measurement of the electron transient effective incident angle，Farady multi-cup for measurement of the time-resolved current density and graphite calorimeter for measuring the total beam energy with correction, are presented. In the condition of space voltage 1.08MV and current 484kA on the diode of flash-2 accelerator，in the distance 20.5cm from cathode measured is total beam energy of 19.1kJ, and of 22kJ after correction. By means of measurement is presented also radial and azimuthal current density on the beam cross-section in different time, and energy fluence on beam spot center with 13% more than its average valu
After briefly analyzing the technical difficulties of diagnosing high fluence electron beam，three new methods for diagnosing parameters, including filtered Farady cup for measurement of the electron transient effective incident angle，Farady multi-cup for measurement of the time-resolved current density and graphite calorimeter for measuring the total beam energy with correction, are presented. In the condition of space voltage 1.08MV and current 484kA on the diode of flash-2 accelerator，in the distance 20.5cm from cathode measured is total beam energy of 19.1kJ, and of 22kJ after correction. By means of measurement is presented also radial and azimuthal current density on the beam cross-section in different time, and energy fluence on beam spot center with 13% more than its average valu
2003,
15.
Abstract:
Electron beam quality is very important in the highaveragepower FEL. According to the characters of CAEP highaveragepower FEL, CW Photoinjector Based DC Gun is proposed in the paper. The beam emittance growth is also investigated under the condition that the beam distribution on the cathode is of Gauss's distribution. The beam emittance growth is mainly due to the space charge effect when the electron beam is accelerated and drifts after acceleration, so the field strength and the voltage are both very important to the injector. With the novel structure of the electrostatic acceleration, the field strength is more than 10MV/m, and the voltage is more than 1MV. After the beam simulation by PARMELA code, 5mm.mrad of the normalized beam emittance (rms) is acquired when the beam charge
Electron beam quality is very important in the highaveragepower FEL. According to the characters of CAEP highaveragepower FEL, CW Photoinjector Based DC Gun is proposed in the paper. The beam emittance growth is also investigated under the condition that the beam distribution on the cathode is of Gauss's distribution. The beam emittance growth is mainly due to the space charge effect when the electron beam is accelerated and drifts after acceleration, so the field strength and the voltage are both very important to the injector. With the novel structure of the electrostatic acceleration, the field strength is more than 10MV/m, and the voltage is more than 1MV. After the beam simulation by PARMELA code, 5mm.mrad of the normalized beam emittance (rms) is acquired when the beam charge
2003,
15.
Abstract:
Under the condition of the same RF power input from the RF transmitter, the amplitude of the RF cavity accelerating voltage depends not only on the quality factor of RF cavity, but also on the coupler matching performance of the RF cavity. This paper describes the experimental results of HIRFL SSC RF cavity accelerating voltage, which is enhanced by improvement of the matching condition of the power fed-in coupler.
Under the condition of the same RF power input from the RF transmitter, the amplitude of the RF cavity accelerating voltage depends not only on the quality factor of RF cavity, but also on the coupler matching performance of the RF cavity. This paper describes the experimental results of HIRFL SSC RF cavity accelerating voltage, which is enhanced by improvement of the matching condition of the power fed-in coupler.
2003,
15.
Abstract:
The results obtained in the theoretical and experimental studies for the application of high power ion beams in certain areas of nuclear physics and material science are reported. The preliminary experimental results of generating 6~7MeV quasimonoenergetic pulsed γrays with high power pulsed proton beams striking 19F target on the Flash Ⅱ accelerator are presented. By placing the target far enough downstream, the quasimonoenergetic pulsed γrays can be discriminated measurementally from the diode bremsstrahlung. This article also describes the other applications of high power ion beams and the preliminary experimental and theoretical results in simulation of soft Xray thermalmechanical effects, generation of high intense pulsed neutrons, equation of state and shockwave phys
The results obtained in the theoretical and experimental studies for the application of high power ion beams in certain areas of nuclear physics and material science are reported. The preliminary experimental results of generating 6~7MeV quasimonoenergetic pulsed γrays with high power pulsed proton beams striking 19F target on the Flash Ⅱ accelerator are presented. By placing the target far enough downstream, the quasimonoenergetic pulsed γrays can be discriminated measurementally from the diode bremsstrahlung. This article also describes the other applications of high power ion beams and the preliminary experimental and theoretical results in simulation of soft Xray thermalmechanical effects, generation of high intense pulsed neutrons, equation of state and shockwave phys
2003,
15.
Abstract:
This paper describes the design considerations of the DragonI linear induction accelerator (LIA) at Institute of Fluid Physics, China Academy of Engineering Physics. The DragonI facility is an electronic linac and consists of a -2.0MV/+1.5MV bipolarity inductive adder injector, 72 accelerating cavities, pulsedpower system, beamtransport, control and auxiliary systems. It can produce an electron beam of 3kA, 20MeV with pulse width of 90ns (FWHM). Good accelerating voltage pulse for each cavity with width of 120ns (FWHM) and up to 60ns flattop within ±1% variation has been obtained for high beam quality.
This paper describes the design considerations of the DragonI linear induction accelerator (LIA) at Institute of Fluid Physics, China Academy of Engineering Physics. The DragonI facility is an electronic linac and consists of a -2.0MV/+1.5MV bipolarity inductive adder injector, 72 accelerating cavities, pulsedpower system, beamtransport, control and auxiliary systems. It can produce an electron beam of 3kA, 20MeV with pulse width of 90ns (FWHM). Good accelerating voltage pulse for each cavity with width of 120ns (FWHM) and up to 60ns flattop within ±1% variation has been obtained for high beam quality.
2003,
15.
Abstract:
There exists the gradient distribution of radial electron velocity due to space charge effect of intense electron beam, and this influences significantly the cooling efficiency. By analysis of the space charge field of intense electron beam in the cooling section of electron cooler system, the variations of electron beam velocity are given. In addition, electron gets the transversal drift velocity and meanwhile causes an additional temperature rise in this crossing field produced by space charge field and longitudinal solenoid field. Using the typical parameters of HIRFLCSR ecooler system, some important conclusions have been drawn.
There exists the gradient distribution of radial electron velocity due to space charge effect of intense electron beam, and this influences significantly the cooling efficiency. By analysis of the space charge field of intense electron beam in the cooling section of electron cooler system, the variations of electron beam velocity are given. In addition, electron gets the transversal drift velocity and meanwhile causes an additional temperature rise in this crossing field produced by space charge field and longitudinal solenoid field. Using the typical parameters of HIRFLCSR ecooler system, some important conclusions have been drawn.
2003,
15.
Abstract:
The pseudospark switch is a new type of closing switch used in pulsed power technology. In this paper, a prototype pseudospark switch is designed. Detailed experiments of voltage characteristics in air have been carried out with the discharge curve being measured. The critical pressure（29Pa）distinguishing pseudospark discharge from glow discharge is determined. Voltage collapse time is measured, transit stage and stable stage of voltage collapse are defined in the first time, experiment data showed, in the same pressure, the transit time is determined by switch voltage, and the stable time is determined by the parameters of the discharge circuit.
The pseudospark switch is a new type of closing switch used in pulsed power technology. In this paper, a prototype pseudospark switch is designed. Detailed experiments of voltage characteristics in air have been carried out with the discharge curve being measured. The critical pressure（29Pa）distinguishing pseudospark discharge from glow discharge is determined. Voltage collapse time is measured, transit stage and stable stage of voltage collapse are defined in the first time, experiment data showed, in the same pressure, the transit time is determined by switch voltage, and the stable time is determined by the parameters of the discharge circuit.
2003,
15.
Abstract:
During the PhaseII project of NSRL, in order to monitor the injecting effectiveness, damping rate and Beta oscillation after update of injection and RF system, a turn-by-turn system of HLS has been produced for storage ring diagnostics. Timing system is an important component of turn-by-turn system. It provides synchronous clock signal with certain bunch in storage ring for data acquisition system. Programmable time-delay and remote control are available in this system. Total time-delay range of this system is 220ns, step 0.5ns. Time jitter of clock signals is less than 200ps.
During the PhaseII project of NSRL, in order to monitor the injecting effectiveness, damping rate and Beta oscillation after update of injection and RF system, a turn-by-turn system of HLS has been produced for storage ring diagnostics. Timing system is an important component of turn-by-turn system. It provides synchronous clock signal with certain bunch in storage ring for data acquisition system. Programmable time-delay and remote control are available in this system. Total time-delay range of this system is 220ns, step 0.5ns. Time jitter of clock signals is less than 200ps.
2003,
15.
Abstract:
Optical limiting effect of nanosecond laser pulses by stimulated Brillouin scattering is investigated. Optical limiting performances and energy stabilization of 2ns Nd: YAG laser pulses were studied both theoretically and experimentally in a nonlinear SBS medium CCl4, the influence of parameters of SBS limiter cell on optical limiting effect predicted by theory were conducted, and superior constant output energy was gained with input energy changing in experimental regime. For the ±13% relative fluctuation of input energy of laser pulses, ±7% relative fluctuation of the transmitted signals was obtained .The experimental results were in good agreement with the predictions by theoretical simulation.
Optical limiting effect of nanosecond laser pulses by stimulated Brillouin scattering is investigated. Optical limiting performances and energy stabilization of 2ns Nd: YAG laser pulses were studied both theoretically and experimentally in a nonlinear SBS medium CCl4, the influence of parameters of SBS limiter cell on optical limiting effect predicted by theory were conducted, and superior constant output energy was gained with input energy changing in experimental regime. For the ±13% relative fluctuation of input energy of laser pulses, ±7% relative fluctuation of the transmitted signals was obtained .The experimental results were in good agreement with the predictions by theoretical simulation.
2003,
15.
Abstract:
The gain optical guiding effects in a chemical oxygeniodine laser (COIL) are found and studied for the first time. The nonuniform distribution of gain in one transverse direction is assumed to be caused by nonuniform injection of the secondary flow. Simple expressions are derived to predict the cavity singlet delta oxygen and intensity profile using the method of Hager et al. Our calculations show that the gain and optical guiding effects have an important influence on the transverse shape of the optical field. The laser beam has a trend to produce similar shape of the gain, which results in some effects such as the offset of the optical beam and the reduce of the output power. The optical guiding can be observed in experiment by measuring the transverse shape of the laser beam.
The gain optical guiding effects in a chemical oxygeniodine laser (COIL) are found and studied for the first time. The nonuniform distribution of gain in one transverse direction is assumed to be caused by nonuniform injection of the secondary flow. Simple expressions are derived to predict the cavity singlet delta oxygen and intensity profile using the method of Hager et al. Our calculations show that the gain and optical guiding effects have an important influence on the transverse shape of the optical field. The laser beam has a trend to produce similar shape of the gain, which results in some effects such as the offset of the optical beam and the reduce of the output power. The optical guiding can be observed in experiment by measuring the transverse shape of the laser beam.
2003,
15.
Abstract:
The Raman scattering spectrum has been used to measure the yield of singlet oxygen molecules in singlet oxygen generator of COIL. We presented the experimental results on a 0.1 mol/s JSOG. The effect of dilution gas on the yield has been studied. The different dilution gas and different dilution ratio have different efficiency to the delta oxygen yield. For a given COIL device, it is essential to choose suitable dilution gas and dilution ratio.
The Raman scattering spectrum has been used to measure the yield of singlet oxygen molecules in singlet oxygen generator of COIL. We presented the experimental results on a 0.1 mol/s JSOG. The effect of dilution gas on the yield has been studied. The different dilution gas and different dilution ratio have different efficiency to the delta oxygen yield. For a given COIL device, it is essential to choose suitable dilution gas and dilution ratio.
2003,
15.
Abstract:
The dynamic stable regions of several kind of resonator, which can be used in high power laser, have been analyzed. Two kind of solid state laser resonator reported recently have been evaluated, and problems in those resonator have been pointed out. The best design for high power and high brightness solid state laser has been put forward: the best resonator is composed of a short radius concave mirror and a convex mirror.
The dynamic stable regions of several kind of resonator, which can be used in high power laser, have been analyzed. Two kind of solid state laser resonator reported recently have been evaluated, and problems in those resonator have been pointed out. The best design for high power and high brightness solid state laser has been put forward: the best resonator is composed of a short radius concave mirror and a convex mirror.
2003,
15.
Abstract:
In an infrared target tracking system, if the background is dynamic, the measured motion of the target will become complicated，and the meaning of the track curve will be unclear.For this reason，an analytical method based on movement compensation is put forward. By compensating relative movement of target with that of background，a clear and explicit target trace is obtained，and intrinsic rules of the target moving are discovered, which will make great help for motion predicting and target tracking.
In an infrared target tracking system, if the background is dynamic, the measured motion of the target will become complicated，and the meaning of the track curve will be unclear.For this reason，an analytical method based on movement compensation is put forward. By compensating relative movement of target with that of background，a clear and explicit target trace is obtained，and intrinsic rules of the target moving are discovered, which will make great help for motion predicting and target tracking.
2003,
15.
Abstract:
The reason for the degradation of adaptive optics system for atmospheric turbulence compensation when branch points are present in phase is analyzed in this paper. The influence of branch points in phase on adaptive optics system is numerically calculated. The result shows that the ability of adaptive optics system can be improved by taking into account the phase discontinuities when branch points are present in light propagation.
The reason for the degradation of adaptive optics system for atmospheric turbulence compensation when branch points are present in phase is analyzed in this paper. The influence of branch points in phase on adaptive optics system is numerically calculated. The result shows that the ability of adaptive optics system can be improved by taking into account the phase discontinuities when branch points are present in light propagation.
2003,
15.
Abstract:
In this paper, colloidbased single-layer SiO2 and ZrO2 thin films were deposited on K9 glass and silicon wafer substrates by Sol-Gel spin-coating method. The films were irradiated by a Q-switched Nd:YAG high power laser whose wavelength was 1064nm and its pulse width was １5ns. The morphologies of the damaged films were observed by SEM and microscope. Damage mechanics of the laser were studied. The results show that solventexchange , UV-irradiation and the addition of PVP are effective methods to improve the laser damage threshold of SolGel thin films．
In this paper, colloidbased single-layer SiO2 and ZrO2 thin films were deposited on K9 glass and silicon wafer substrates by Sol-Gel spin-coating method. The films were irradiated by a Q-switched Nd:YAG high power laser whose wavelength was 1064nm and its pulse width was １5ns. The morphologies of the damaged films were observed by SEM and microscope. Damage mechanics of the laser were studied. The results show that solventexchange , UV-irradiation and the addition of PVP are effective methods to improve the laser damage threshold of SolGel thin films．
2003,
15.
Abstract:
A uniform soft X-ray multiplayers deposition technology is introduced in this paper, in which the platter revolution speed is varied as a function of its position relative to the sputtering source. Using this method, the relative thickness variation of the Mo/Si multilayers with central wavelength of 13.5nm was reduced from 7% to 1% peak to valley over 150mm diameter region on flat Si substrates.
A uniform soft X-ray multiplayers deposition technology is introduced in this paper, in which the platter revolution speed is varied as a function of its position relative to the sputtering source. Using this method, the relative thickness variation of the Mo/Si multilayers with central wavelength of 13.5nm was reduced from 7% to 1% peak to valley over 150mm diameter region on flat Si substrates.
2003,
15.
Abstract:
The bonding technique of high power diode laser package is studied and the method of making indium solder with evaporating deposition in high vacuum is mastered. The multiplayer bonding experiment is carried out without scaling powder. The performances of packaged CW and QCW lasers are measured. The experiment's results show that multilayer bonding technique with indium and InSn alloy for laser package is practical.
The bonding technique of high power diode laser package is studied and the method of making indium solder with evaporating deposition in high vacuum is mastered. The multiplayer bonding experiment is carried out without scaling powder. The performances of packaged CW and QCW lasers are measured. The experiment's results show that multilayer bonding technique with indium and InSn alloy for laser package is practical.
2003,
15.
Abstract:
In this paper, the depth of color separation grating applied in ICF system is optimized firstly for good separating effect. After this, duty cycle error and the trapezoid structure are analyzed. A probable scope of technologic error that make the color separation grating have good effect is given in the end.
In this paper, the depth of color separation grating applied in ICF system is optimized firstly for good separating effect. After this, duty cycle error and the trapezoid structure are analyzed. A probable scope of technologic error that make the color separation grating have good effect is given in the end.
2003,
15.
Abstract:
The fully relativistic mechanics (GRASP2) with Breit and QED corrections is used to calculate the magnetic dipole M1 1s22s22p 2P3/22P1/2(Z=10～100) transition energy level intervals and transition probabilities and oscillator strengths of the groundstate boron isoelectronic sequence. In calculation, we considered the significant nuclear volume effect and Breit and QED correction effects so that excellent comparison was obtained throughout the range of Z. The results are in excellent agreement with those of observations, and show no systematic errors. The relation of our results to those of other recent calculations is investigated.
The fully relativistic mechanics (GRASP2) with Breit and QED corrections is used to calculate the magnetic dipole M1 1s22s22p 2P3/22P1/2(Z=10～100) transition energy level intervals and transition probabilities and oscillator strengths of the groundstate boron isoelectronic sequence. In calculation, we considered the significant nuclear volume effect and Breit and QED correction effects so that excellent comparison was obtained throughout the range of Z. The results are in excellent agreement with those of observations, and show no systematic errors. The relation of our results to those of other recent calculations is investigated.
2003,
15.
Abstract:
Spatial localized structure(solitonlike electromagnetic wave) has been observed following the interaction of an intense and short laser pulse with underdense plasma using the two dimensional PIC simulation.The formation mechanism and spatiotemporal evolution of the solitonlike wave and related phenomena such as the energy exchange process of electromagnetic field with plasma wave, the frequency downshift of laser pulse,and the caviton formation were discussed. Once EM wave oscilation frequence is lower than plasma frequcnce, the localized structure will appear and it is easier to form in higher initial plasma density.
Spatial localized structure(solitonlike electromagnetic wave) has been observed following the interaction of an intense and short laser pulse with underdense plasma using the two dimensional PIC simulation.The formation mechanism and spatiotemporal evolution of the solitonlike wave and related phenomena such as the energy exchange process of electromagnetic field with plasma wave, the frequency downshift of laser pulse,and the caviton formation were discussed. Once EM wave oscilation frequence is lower than plasma frequcnce, the localized structure will appear and it is easier to form in higher initial plasma density.
2003,
15.
Abstract:
This paper presents the features, including the radiation pattern and power, as well as the mode information, of the high power microwaves radiated by a reflex triode operating in a laboratory, which are obtained through an improved farfield measurement method put forward here. The measured results show that the radiation power exceeds 300MW with a frequency of 2.8GHz and a pulse width of about 150ns, and that several modes are generated with TE11 mode included.
This paper presents the features, including the radiation pattern and power, as well as the mode information, of the high power microwaves radiated by a reflex triode operating in a laboratory, which are obtained through an improved farfield measurement method put forward here. The measured results show that the radiation power exceeds 300MW with a frequency of 2.8GHz and a pulse width of about 150ns, and that several modes are generated with TE11 mode included.
2003,
15.
Abstract:
For generating high power microwave in free space the physical optics is used to analyze offset paraboloid antennas with three types of 7 element array horn feeds: one dimension sectorial horn array, two dimension triangle pyramidal horn array and two dimension triangle circular horn array. On condition that the maximum electric fields on the aperture of all the horns are equal, the array feeds radiate axial symmetrical main lobe and the antennas are with same reflector diameter, clean space and edge taper, the radiation characteristics of the antenna with sectorial horn array feed are the best of the three. However, the circular horn array has the most stable radiation directibity when the phase difference between the elements of the horn array is changed, the circular horn array is the b
For generating high power microwave in free space the physical optics is used to analyze offset paraboloid antennas with three types of 7 element array horn feeds: one dimension sectorial horn array, two dimension triangle pyramidal horn array and two dimension triangle circular horn array. On condition that the maximum electric fields on the aperture of all the horns are equal, the array feeds radiate axial symmetrical main lobe and the antennas are with same reflector diameter, clean space and edge taper, the radiation characteristics of the antenna with sectorial horn array feed are the best of the three. However, the circular horn array has the most stable radiation directibity when the phase difference between the elements of the horn array is changed, the circular horn array is the b
2003,
15.
Abstract:
According to the current waveform in standard IEC61000-4-2, two analytical expressions of the standard current are analyzed and then a new one based on pulse function is proposed. The new expression is consistent with the new standard IEC61000-4-2, in which bath the current and its derivative are zero at the zero moment, and the waveform basically is agreed with the measured one.
According to the current waveform in standard IEC61000-4-2, two analytical expressions of the standard current are analyzed and then a new one based on pulse function is proposed. The new expression is consistent with the new standard IEC61000-4-2, in which bath the current and its derivative are zero at the zero moment, and the waveform basically is agreed with the measured one.
2003,
15.
Abstract:
The authors develop a method which is called impulse respond method,based on the traditional resonant method. The impulse method is more suitable for numerical calculation .Integrated with the method introduced in one of the references Y·Camel, 1990, the impulse method becomes a fast method successfully used in the author's HL-RBWO research work．
The authors develop a method which is called impulse respond method,based on the traditional resonant method. The impulse method is more suitable for numerical calculation .Integrated with the method introduced in one of the references Y·Camel, 1990, the impulse method becomes a fast method successfully used in the author's HL-RBWO research work．
2003,
15.
Abstract:
A convenient method is presented to obtain the dispersive characteristics of TM0n electromagnetic modes in the rectangular corrugation overmoded slow wave structure(SWS) by numerical simulation. The influence of average radius, period, amplitude of the SWS on the field distribution properties of the eigenmodes is investigated; the condition to maintain the surface and the volume waves is discussed; the reason that overmoded SWS can still operate in a single mode is analyzed. The results show that when the overmoded SWS structure parameters satisfy the condition and are matched with the annular beam voltage and radius, the total field of TM01 mode with longitudinal wavenumber of beamwave synchronous point locating near π mode is surface wave, and the system can operate in single TM01 mod
A convenient method is presented to obtain the dispersive characteristics of TM0n electromagnetic modes in the rectangular corrugation overmoded slow wave structure(SWS) by numerical simulation. The influence of average radius, period, amplitude of the SWS on the field distribution properties of the eigenmodes is investigated; the condition to maintain the surface and the volume waves is discussed; the reason that overmoded SWS can still operate in a single mode is analyzed. The results show that when the overmoded SWS structure parameters satisfy the condition and are matched with the annular beam voltage and radius, the total field of TM01 mode with longitudinal wavenumber of beamwave synchronous point locating near π mode is surface wave, and the system can operate in single TM01 mod
2003,
15.
Abstract:
The coupling processes of electromagnetic pulse with narrow slot and cavity with slot are simulated using the finite-difference time-domain (FDTD) method. For analyzing the variation of energy with the transmission path and time, the coupling transmission coefficient of energy is defined. When narrow slot and cavity with slot are excited by electromagnetic pulse, the resonant characteristics of coupling energy are obtained. If the width of slots is smaller than 0.2λ，it is found clearly that the energy of electromagnetic pulse coupling through narrow slots will have regular fluctuation according to the thickness of narrow slots.
The coupling processes of electromagnetic pulse with narrow slot and cavity with slot are simulated using the finite-difference time-domain (FDTD) method. For analyzing the variation of energy with the transmission path and time, the coupling transmission coefficient of energy is defined. When narrow slot and cavity with slot are excited by electromagnetic pulse, the resonant characteristics of coupling energy are obtained. If the width of slots is smaller than 0.2λ，it is found clearly that the energy of electromagnetic pulse coupling through narrow slots will have regular fluctuation according to the thickness of narrow slots.
