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RSS2009 Vol. 21, No. 06
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2009,
21.
Abstract:
This paper summarized worldwide latest progresses in fast Z-pinch plasma research and the application prospect of fusion energy. The meaning of fast Z-pinch plasma research for high energy density physics and inertial confinement fusion was introduced, and the feasibility study for high-yield low-cost fusion energy technology was forecasted. Finally, possible technical challenges for fusion energy were primarily explored.
This paper summarized worldwide latest progresses in fast Z-pinch plasma research and the application prospect of fusion energy. The meaning of fast Z-pinch plasma research for high energy density physics and inertial confinement fusion was introduced, and the feasibility study for high-yield low-cost fusion energy technology was forecasted. Finally, possible technical challenges for fusion energy were primarily explored.
2009,
21.
Abstract:
An experiment is designed to explore the ambient temperature distribution in an ICF driver’s target building. Multi-channel PC-2WS temperature monitoring recorders and PTWD-2A precision temperature sensors are used to measure temperatures on the three vertical cross-sections in the building, and the collected data have been handled by MATLAB. The experiment and analysis show that the design of the heating ventilation and air conditioning(HVAC) system can maintain the temperature stability throughout the building. However, because of the impact of heat in the target chamber, larger local environmental temperature gradients appear near the marshalling yard, the staff region on the middle floor, and equipments on the lower floor which needs to be controlled.
An experiment is designed to explore the ambient temperature distribution in an ICF driver’s target building. Multi-channel PC-2WS temperature monitoring recorders and PTWD-2A precision temperature sensors are used to measure temperatures on the three vertical cross-sections in the building, and the collected data have been handled by MATLAB. The experiment and analysis show that the design of the heating ventilation and air conditioning(HVAC) system can maintain the temperature stability throughout the building. However, because of the impact of heat in the target chamber, larger local environmental temperature gradients appear near the marshalling yard, the staff region on the middle floor, and equipments on the lower floor which needs to be controlled.
2009,
21.
Abstract:
An auxiliary optical system has been designed, which can provide precise positioning for aiming Kirkpatrick-Baez(KB) microscope object location. An 8 keV X-ray imaging system by KB microscope with periodic multilayer films has been designed. The field of view and depth of field in the resolution of 5 μm are got, and then the corresponding point and depth of field in diagnostic experiments are calculated. Based on the object-image relations and precision of the KB microscope, an auxiliary visible light imaging system is designed and X-ray imaging experiments are performed, which can achieve equivalent aiming between the visible imaging system and the KB microscope. The results show that ±20 μm vertical axis plane and ±300 μm axial accuracy are achieved through the auxiliary optical pat
An auxiliary optical system has been designed, which can provide precise positioning for aiming Kirkpatrick-Baez(KB) microscope object location. An 8 keV X-ray imaging system by KB microscope with periodic multilayer films has been designed. The field of view and depth of field in the resolution of 5 μm are got, and then the corresponding point and depth of field in diagnostic experiments are calculated. Based on the object-image relations and precision of the KB microscope, an auxiliary visible light imaging system is designed and X-ray imaging experiments are performed, which can achieve equivalent aiming between the visible imaging system and the KB microscope. The results show that ±20 μm vertical axis plane and ±300 μm axial accuracy are achieved through the auxiliary optical pat
2009,
21.
Abstract:
Frequency downshift and upshift of microwaves reflected by laser-induced plasma were experimentally studied. In the experiments, the microwave produced by a microwave generator impinged on the laser-induced plasma. The frequency of the microwave reflected by the pulsed plasmas was measured by a spectrum analyzer. Both in plasma expansion and extinguishing processes, the maximal frequency shift of the reflected microwave was found to be a function of laser power density and the frequency of the incident microwave. The results show that the maximal frequency shift monotonously increases with increasing the laser power density, and decreases with increasing the frequency of the incident microwave．
Frequency downshift and upshift of microwaves reflected by laser-induced plasma were experimentally studied. In the experiments, the microwave produced by a microwave generator impinged on the laser-induced plasma. The frequency of the microwave reflected by the pulsed plasmas was measured by a spectrum analyzer. Both in plasma expansion and extinguishing processes, the maximal frequency shift of the reflected microwave was found to be a function of laser power density and the frequency of the incident microwave. The results show that the maximal frequency shift monotonously increases with increasing the laser power density, and decreases with increasing the frequency of the incident microwave．
2009,
21.
Abstract:
To study the deformation of optical surface when optical components deposited with high power laser films are exposed to room air, theoretical analysis was carried out to make clear that water-induced stress is and it is the main reason to cause such optical surface deformation including two formation mechanism: physical mechanism and chemical mechanism. A series of experiments were designed to investigate the transformation tendency of film stress, and the deformation was found with aging effect and humidity effect during storage. Which corresponding to the chemical mechanism and physical mechanism respectively.
To study the deformation of optical surface when optical components deposited with high power laser films are exposed to room air, theoretical analysis was carried out to make clear that water-induced stress is and it is the main reason to cause such optical surface deformation including two formation mechanism: physical mechanism and chemical mechanism. A series of experiments were designed to investigate the transformation tendency of film stress, and the deformation was found with aging effect and humidity effect during storage. Which corresponding to the chemical mechanism and physical mechanism respectively.
2009,
21.
Abstract:
The preparation of microcellular foam in sub-millimeter cylindrical gold targets is described. Small, open-ended, gold cylinders of 400 μm diameter, 700 μm length, and 20 μm wall thickness were fabricated by electroplating gold onto a silicon bronze mandrel and leaching the mandrel with concentrated nitric acid. After several rinsing and cleaning steps, the cylinders were filled with a solution containing acrylate monomers. The solution was polymerized in situ with ultraviolet light to produce a gel. Precipitation of these gels in a non-solvent such as methanol and subsequent drying by means of a critical point drying apparatus produced cylinders filled with microporous foams. The foams have densities of 50 mg·cm-3 and cell sizes no more than 1 μm. They fill the cylinders completely
The preparation of microcellular foam in sub-millimeter cylindrical gold targets is described. Small, open-ended, gold cylinders of 400 μm diameter, 700 μm length, and 20 μm wall thickness were fabricated by electroplating gold onto a silicon bronze mandrel and leaching the mandrel with concentrated nitric acid. After several rinsing and cleaning steps, the cylinders were filled with a solution containing acrylate monomers. The solution was polymerized in situ with ultraviolet light to produce a gel. Precipitation of these gels in a non-solvent such as methanol and subsequent drying by means of a critical point drying apparatus produced cylinders filled with microporous foams. The foams have densities of 50 mg·cm-3 and cell sizes no more than 1 μm. They fill the cylinders completely
2009,
21.
Abstract:
Available test technique for the subsurface defects to be applied in optical process has become an urgent requirement of the manufacture of optics with high resistance to damage. Based on theory of total internal reflection illumination, the research on total internal reflection microscopy(TIRM) technique is done experimentally. It is proved that the TIRM technique for the detection of the subsurface defects is valid, the transformation of the polarization or the incident angle will affect the illumination distribution below the interface, hence the change in visibility of the tiny defects can be used to evaluate the size of the defects in the depth direction. The depth of the subsurface defects can also be gained according to the focusing distance of the microscopy from the interface to t
Available test technique for the subsurface defects to be applied in optical process has become an urgent requirement of the manufacture of optics with high resistance to damage. Based on theory of total internal reflection illumination, the research on total internal reflection microscopy(TIRM) technique is done experimentally. It is proved that the TIRM technique for the detection of the subsurface defects is valid, the transformation of the polarization or the incident angle will affect the illumination distribution below the interface, hence the change in visibility of the tiny defects can be used to evaluate the size of the defects in the depth direction. The depth of the subsurface defects can also be gained according to the focusing distance of the microscopy from the interface to t
2009,
21.
Abstract:
To better understand the basic physics of fast ignition target compression, the effects of laser pulse shape on the compression of flat target are analyzed and simulated using hydrodynamic code MULTI. Results show that high material density can be achieved through optimizing the initial intensity, rising time and the intensity slope of the laser pulse.
To better understand the basic physics of fast ignition target compression, the effects of laser pulse shape on the compression of flat target are analyzed and simulated using hydrodynamic code MULTI. Results show that high material density can be achieved through optimizing the initial intensity, rising time and the intensity slope of the laser pulse.
2009,
21.
Abstract:
Shock compression is the main source of entropy changes in ICF implosions. How to realize a nearly isentropic implosion with a series of shock waves after pulse shaping will be crucial for the optimization design of ignition targets. With the ideal and realistic equtions of state, entropy and density changes of DT with a series of shock compressions are calculated. With an initial pressure of 0.1 TPa which is then proceeded to 10 TPa with three consecutive shocks, the compressibility of DT will not be affected by the corresponding entropy change. It is found that increasing the number of shocks has a small effect on entropy change and compression ratio of DT.
Shock compression is the main source of entropy changes in ICF implosions. How to realize a nearly isentropic implosion with a series of shock waves after pulse shaping will be crucial for the optimization design of ignition targets. With the ideal and realistic equtions of state, entropy and density changes of DT with a series of shock compressions are calculated. With an initial pressure of 0.1 TPa which is then proceeded to 10 TPa with three consecutive shocks, the compressibility of DT will not be affected by the corresponding entropy change. It is found that increasing the number of shocks has a small effect on entropy change and compression ratio of DT.
2009,
21.
Abstract:
The effect of the thermal shock and thermal conduction of target irradiated by multi-pulse laser is studied. Based on the non-Fourier law and thermo-elastic theory, the non-Fourier expressions of the temperature field and the thermal stress field of target under multi-pulse laser irradiation were deduced. Taken stainless steel target as an example, thermal conduction and thermal stress equations under an appropriate boundary condition were solved by using the finite difference method. The temperature distribution and thermal stress distribution were obtained as function of time, relaxation time and location. The results show that the effect of thermal conduction of target irradiated multi-pulsed laser presents the temperature waves and the variety of temperature waves is postponed by the r
The effect of the thermal shock and thermal conduction of target irradiated by multi-pulse laser is studied. Based on the non-Fourier law and thermo-elastic theory, the non-Fourier expressions of the temperature field and the thermal stress field of target under multi-pulse laser irradiation were deduced. Taken stainless steel target as an example, thermal conduction and thermal stress equations under an appropriate boundary condition were solved by using the finite difference method. The temperature distribution and thermal stress distribution were obtained as function of time, relaxation time and location. The results show that the effect of thermal conduction of target irradiated multi-pulsed laser presents the temperature waves and the variety of temperature waves is postponed by the r
2009,
21.
Abstract:
The thermal distortions of a high average power solid-state laser could be compensated by cube corner arrays (CCA) due to the quasi phase conjugation. But the applications of a CCA have been limited when it is used as a resonator, because of the numerous cavity modes caused by its retro-reflection characteristics and the high loss caused by the edge diffraction of the CCA. The output properties of a cube corner array resonator are analyzed and a new method to obtain single mode has been proposed by using an intracavity filter to suppress the high order cavity modes. The theoretical and experimental results show that the output beam quality could be improved to nearly 5 times the diffraction limit by cube corner arrays with intracavity filter．
The thermal distortions of a high average power solid-state laser could be compensated by cube corner arrays (CCA) due to the quasi phase conjugation. But the applications of a CCA have been limited when it is used as a resonator, because of the numerous cavity modes caused by its retro-reflection characteristics and the high loss caused by the edge diffraction of the CCA. The output properties of a cube corner array resonator are analyzed and a new method to obtain single mode has been proposed by using an intracavity filter to suppress the high order cavity modes. The theoretical and experimental results show that the output beam quality could be improved to nearly 5 times the diffraction limit by cube corner arrays with intracavity filter．
2009,
21.
Abstract:
A laser-induced breakdown spectroscopy(LIBS) set-up has been established, and a series of experiments have been carried out with soil samples. The calibration curves of the lines intensities versus the mass fraction of the elements were acquired by the experiment. Eighteen elements including Mg, Ca and Na were found in the sample of the soil around the South-Central University for Nationalities by qualitative analysis. Only three elements, Fe, Mg and Ca, were found in the rock at Zhuyufeng peak. These results indicate that the physical composition of soil sample impact on the precision of LIBS.
A laser-induced breakdown spectroscopy(LIBS) set-up has been established, and a series of experiments have been carried out with soil samples. The calibration curves of the lines intensities versus the mass fraction of the elements were acquired by the experiment. Eighteen elements including Mg, Ca and Na were found in the sample of the soil around the South-Central University for Nationalities by qualitative analysis. Only three elements, Fe, Mg and Ca, were found in the rock at Zhuyufeng peak. These results indicate that the physical composition of soil sample impact on the precision of LIBS.
2009,
21.
Abstract:
In order to improve polymer’s propulsion Performance, polyformaldehydes(POM) seeded with metallic powders have been researched with a CO2 laser.The results show that metallic powders can improve POM’s propulsion performance under proper condition. The largest momentum coupling coefficient of POM rises from 12×10-5 N/W to 21.72×10-5 N/W after added with micron aluminium powders. When the POM seeded with micron aluminium powders is put into a long cylindrical model, the largest momentum coupling coefficient and specific impulse rise to 61.64×10-5 N/W and 727.32 s, respectively. The corresponding energy usage ratio is over 100%. This indicates that the target has reacted with air．
In order to improve polymer’s propulsion Performance, polyformaldehydes(POM) seeded with metallic powders have been researched with a CO2 laser.The results show that metallic powders can improve POM’s propulsion performance under proper condition. The largest momentum coupling coefficient of POM rises from 12×10-5 N/W to 21.72×10-5 N/W after added with micron aluminium powders. When the POM seeded with micron aluminium powders is put into a long cylindrical model, the largest momentum coupling coefficient and specific impulse rise to 61.64×10-5 N/W and 727.32 s, respectively. The corresponding energy usage ratio is over 100%. This indicates that the target has reacted with air．
2009,
21.
Abstract:
Jets injection in the TRIP gain generator can be either pure helium or mixture of helium and deuterium. Both of the cavity flowfield were numerically simulated to investigate their difference. The simulation results show that mixing enhanement of trip jets is obvious, the static pressure and static temperature have evident rising. Small signal gain’s peak value of each spectrum increases and its location moves upstream, while the small signal gain falls faster than that of cases without trip jets, and region of negative gain appear soon. Reaction between deuterium and fluorine is weak, which would not affect the main stream. Comparing the cases of trip jets and pure helium, the small signal gain of spectrum rises faster upstream, while the peak value preserves basically.
Jets injection in the TRIP gain generator can be either pure helium or mixture of helium and deuterium. Both of the cavity flowfield were numerically simulated to investigate their difference. The simulation results show that mixing enhanement of trip jets is obvious, the static pressure and static temperature have evident rising. Small signal gain’s peak value of each spectrum increases and its location moves upstream, while the small signal gain falls faster than that of cases without trip jets, and region of negative gain appear soon. Reaction between deuterium and fluorine is weak, which would not affect the main stream. Comparing the cases of trip jets and pure helium, the small signal gain of spectrum rises faster upstream, while the peak value preserves basically.
2009,
21.
Abstract:
Frequency feature of an S-band tapered magnetically insulated transmission line oscillator with slowly tapered vanes and sharply tapered vanes is analyzed. Comparing the frequency hopping phenomena in the experiments and cavity characteristics analysis for this device shows that the hopped frequency is also π moded and its distribution is different from the stable π mode. Experiments by adjusting the period of the sharply tapered vanes have proved the analysis result. Further research indicates that matching driving pulse power source, perfect vacuum and proper diode position ensure stable operation of the tapered MILO.
Frequency feature of an S-band tapered magnetically insulated transmission line oscillator with slowly tapered vanes and sharply tapered vanes is analyzed. Comparing the frequency hopping phenomena in the experiments and cavity characteristics analysis for this device shows that the hopped frequency is also π moded and its distribution is different from the stable π mode. Experiments by adjusting the period of the sharply tapered vanes have proved the analysis result. Further research indicates that matching driving pulse power source, perfect vacuum and proper diode position ensure stable operation of the tapered MILO.
2009,
21.
Abstract:
Based on negative refractive index materials' constitutive relations, the finite-difference time-domain(FDTD) formulations are obtained by using piecewise linear recursive convolution(PLRC) method. It is named PLRC-FDTD method. Then the PLRC-FDTD method is applied to calculate radar scattering sections(RCS) of perfectly conducting cylinder coated with negative refractive index materials (NIRM). The effect of the plasma parameters on the radar scattering cross sections is investigated and some numerical results are obtained. The results indicate that an appropriate NIRM coating may efficiently reduce the RCS of a metallic target.
Based on negative refractive index materials' constitutive relations, the finite-difference time-domain(FDTD) formulations are obtained by using piecewise linear recursive convolution(PLRC) method. It is named PLRC-FDTD method. Then the PLRC-FDTD method is applied to calculate radar scattering sections(RCS) of perfectly conducting cylinder coated with negative refractive index materials (NIRM). The effect of the plasma parameters on the radar scattering cross sections is investigated and some numerical results are obtained. The results indicate that an appropriate NIRM coating may efficiently reduce the RCS of a metallic target.
2009,
21.
Abstract:
Combining the characteristics of foil focusing and electrostatically-charged-wire focusing, the transmission of foil-focused intense relativistic annular electron beam in a coaxial cylindrical waveguide is studied. The electric filed and the space-charge-limited current is derived by calculating Poisson equation via numerical calculation. The equilibrium conditions and tracks of envelope electrons are attained through motion the electron equation．
Combining the characteristics of foil focusing and electrostatically-charged-wire focusing, the transmission of foil-focused intense relativistic annular electron beam in a coaxial cylindrical waveguide is studied. The electric filed and the space-charge-limited current is derived by calculating Poisson equation via numerical calculation. The equilibrium conditions and tracks of envelope electrons are attained through motion the electron equation．
2009,
21.
Abstract:
The three-dimensional whole-tube model for a C-band relativistic klystron amplifier is designed. With the integrated model, the high frequency characteristic analysis and optimization of the tube are presented. A three-dimensional full-electromagnetic particle-in-cell(PIC) code is used to simulate the absorption of injected microwave, and to simulate the fundamental harmonic modulated current when electron beams propagate through the input and idler cavity gaps. The simulated result show that the input cavity matches with the input waveguide and most energy of the input microwave is absorbed by electron beams and the resonant cavities. The modulation depths of the fundamental harmonic modulated current are about 11% at 20 cm downstream of the input cavity gap and about 76% at 15 cm downstr
The three-dimensional whole-tube model for a C-band relativistic klystron amplifier is designed. With the integrated model, the high frequency characteristic analysis and optimization of the tube are presented. A three-dimensional full-electromagnetic particle-in-cell(PIC) code is used to simulate the absorption of injected microwave, and to simulate the fundamental harmonic modulated current when electron beams propagate through the input and idler cavity gaps. The simulated result show that the input cavity matches with the input waveguide and most energy of the input microwave is absorbed by electron beams and the resonant cavities. The modulation depths of the fundamental harmonic modulated current are about 11% at 20 cm downstream of the input cavity gap and about 76% at 15 cm downstr
2009,
21.
Abstract:
The magnetically insulated transmission line oscillator(MILO) is a crossed-field microwave tube that is closely related to the linear magnetron. The theoretical model of the self-magnetically insulated transmission line oscillator is established, and the formula of the insulating current is given. Then the formula of the maximum spoke current is given, and the maximum efficiency of the load-limited MILO is analyzed. A new type of gap-current MILO is presented. The PIC simulation shows that the steady-state value of average output power of this MILO is around 6.1 GW with an effciency of about 18.64% when the AK-gap voltage is 590 kV, the current is 55.47 kA, and the corresponding frequency is 1.24 GHz. The efficiency of the gap-current MILO is about 6% higher than that of the load-limited M
The magnetically insulated transmission line oscillator(MILO) is a crossed-field microwave tube that is closely related to the linear magnetron. The theoretical model of the self-magnetically insulated transmission line oscillator is established, and the formula of the insulating current is given. Then the formula of the maximum spoke current is given, and the maximum efficiency of the load-limited MILO is analyzed. A new type of gap-current MILO is presented. The PIC simulation shows that the steady-state value of average output power of this MILO is around 6.1 GW with an effciency of about 18.64% when the AK-gap voltage is 590 kV, the current is 55.47 kA, and the corresponding frequency is 1.24 GHz. The efficiency of the gap-current MILO is about 6% higher than that of the load-limited M
2009,
21.
Abstract:
The space-charge field characteristics of a uniform sheet electron beam in a rectangular waveguide have been investigated theoretically and numerically. The expressions of the space-charge field components are derived, and numerically calculated for different dimensions and current densities. Results show that, for a constant current density of the sheet beam, the sheet beam could propagate with a larger current when the beam cross-section is wider. In addition, the space-charge field of the sheet electron beam with a constant current density will not be enhanced while increasing the width of the beam, but will be enhanced while increasing the thickness of the beam. However, only the electric field component along the direction of the long side of the beam cross-section is weakened by incr
The space-charge field characteristics of a uniform sheet electron beam in a rectangular waveguide have been investigated theoretically and numerically. The expressions of the space-charge field components are derived, and numerically calculated for different dimensions and current densities. Results show that, for a constant current density of the sheet beam, the sheet beam could propagate with a larger current when the beam cross-section is wider. In addition, the space-charge field of the sheet electron beam with a constant current density will not be enhanced while increasing the width of the beam, but will be enhanced while increasing the thickness of the beam. However, only the electric field component along the direction of the long side of the beam cross-section is weakened by incr
2009,
21.
Abstract:
A compact gigawatt relativistic backward wave oscillator with coaxial extractor is investigated using the KARAT 2-5 D particle simulation code. Detailed physical interaction pictures of beam and wave in the oscillator are presented. Simulation results show that under the same parameters (electron beam of 700 keV energy and 11.5 kA current, guiding magnatic field of 10 T), an Lband microwave with an average output power of 2.66 GW can be obtained using an inner conductor, and an S-band microwave with an average output power of 2.0 GW for no inner conductor condition. The average power efficienices are about 34% and 24%, respectively．
A compact gigawatt relativistic backward wave oscillator with coaxial extractor is investigated using the KARAT 2-5 D particle simulation code. Detailed physical interaction pictures of beam and wave in the oscillator are presented. Simulation results show that under the same parameters (electron beam of 700 keV energy and 11.5 kA current, guiding magnatic field of 10 T), an Lband microwave with an average output power of 2.66 GW can be obtained using an inner conductor, and an S-band microwave with an average output power of 2.0 GW for no inner conductor condition. The average power efficienices are about 34% and 24%, respectively．
2009,
21.
Abstract:
The Mini-LIA is a double-pulse linear induction electron accelerator with megahertz repetition rates, which consists of a double-pulse power system, a thermal cathode electron gun, two induction cells, beam transportation systems and diagnosis systems, etc. Experiments of the Mini-LIA have been conducted. The double-pulse high voltage was obtained with several hundred nanosecond pulse intervals (i.e. megahertz repetition rate) and each pulse had an 80 kV amplitude with a FWHM of 80 ns. In the gap of the induction cell, the double-pulse accelerating electric field was measured via E-field probes, and the double-pulse electron beam with a current about 1.1 A has been obtained at the Mini-LIA exit. These experimental results show that the double-pulse high voltage with megahertz repetition ra
The Mini-LIA is a double-pulse linear induction electron accelerator with megahertz repetition rates, which consists of a double-pulse power system, a thermal cathode electron gun, two induction cells, beam transportation systems and diagnosis systems, etc. Experiments of the Mini-LIA have been conducted. The double-pulse high voltage was obtained with several hundred nanosecond pulse intervals (i.e. megahertz repetition rate) and each pulse had an 80 kV amplitude with a FWHM of 80 ns. In the gap of the induction cell, the double-pulse accelerating electric field was measured via E-field probes, and the double-pulse electron beam with a current about 1.1 A has been obtained at the Mini-LIA exit. These experimental results show that the double-pulse high voltage with megahertz repetition ra
2009,
21.
Abstract:
The local bump of beam closed orbit is designed for some specific beamline in the Hefei Light Source. The design demands local orbit adjustment of 1~2 mm, horizontal and vertical closed orbit distortion outside the bump orbit less than 50 μm and 30 μm. In this paper, the local bump principle, hardware components, software design and the results are described. The local bump system adopts the orbit setting algorithm, and consists of the beam orbit measure system, the corrector magnet system and the control system. The main operation results of the system show that maximum values of horizontal and vertical local orbit adjustment are 2 mm and 1.5 mm respectively, horizontal and vertical closed orbit distortion outside bump orbit are less than 45.14 μm and 27.62 μm respectively.
The local bump of beam closed orbit is designed for some specific beamline in the Hefei Light Source. The design demands local orbit adjustment of 1~2 mm, horizontal and vertical closed orbit distortion outside the bump orbit less than 50 μm and 30 μm. In this paper, the local bump principle, hardware components, software design and the results are described. The local bump system adopts the orbit setting algorithm, and consists of the beam orbit measure system, the corrector magnet system and the control system. The main operation results of the system show that maximum values of horizontal and vertical local orbit adjustment are 2 mm and 1.5 mm respectively, horizontal and vertical closed orbit distortion outside bump orbit are less than 45.14 μm and 27.62 μm respectively.
2009,
21.
Abstract:
According to the interaction cavity structure of HPM, a two-surface multipactor discharge model was presented. Through the calculation of susceptibility curves and secondary electron evolution using statistical and Monte-Carlo simulation methods, the impacts of parameters of RF field and the cavity structure on multipactor discharge were analyzed. The results show that: the high-frequency field is more liable to multipactor than the low-frequency field is, the secondary electron evolution of multipactor is non-monotonic related to RF field intensity and cavity structure, and the resonant region at grazing incidence is much larger than that at normal incidence,which accords with theoretical analysis.
According to the interaction cavity structure of HPM, a two-surface multipactor discharge model was presented. Through the calculation of susceptibility curves and secondary electron evolution using statistical and Monte-Carlo simulation methods, the impacts of parameters of RF field and the cavity structure on multipactor discharge were analyzed. The results show that: the high-frequency field is more liable to multipactor than the low-frequency field is, the secondary electron evolution of multipactor is non-monotonic related to RF field intensity and cavity structure, and the resonant region at grazing incidence is much larger than that at normal incidence,which accords with theoretical analysis.
2009,
21.
Abstract:
FPGA and dedicated micro-controller chips are widely used in HIRFL-CSR monitor and control systems.This paper discusses the characteristics of HIRFL-CSR’s dedicated micro-controllers and it’s requirement for micro-controllers. Using programmable technology and Nios-Ⅱ processor, we have designed and implemented a reconfigurable embedded micro（controller in altera cycloneⅡ2c35f484 FPGA. The micro-controller which has low hardware cost and 185 MHz maximum operating frequency can replace the dedicated micro-controller chips, decrease complexity of hardware design and save costs.
FPGA and dedicated micro-controller chips are widely used in HIRFL-CSR monitor and control systems.This paper discusses the characteristics of HIRFL-CSR’s dedicated micro-controllers and it’s requirement for micro-controllers. Using programmable technology and Nios-Ⅱ processor, we have designed and implemented a reconfigurable embedded micro（controller in altera cycloneⅡ2c35f484 FPGA. The micro-controller which has low hardware cost and 185 MHz maximum operating frequency can replace the dedicated micro-controller chips, decrease complexity of hardware design and save costs.
2009,
21.
Abstract:
Small angle X-ray scattering(SAXS) methods were employed to investigate the aggregations of Pt nanoparticles in three kinds of Pt/C catalysts produced by microwave heating process, soakage-reducing process and glycol synthesis process. The experimental results showed information of characteristic size, surface area and size distributions of Pt nanoparticles and aggregations in three catalysts. The TEM images are in agreement with SAXS conclusions. The investigation showed that the processes affected the characters of Pt nanoparticles and their aggregations in Pt/C catalyst differently. Pt particles produced by microwave heating process scatter uniformly on carbon supports, and have relatively a large surface and sharp size-distribution. Applying the soakage-reducing process and glycol synt
Small angle X-ray scattering(SAXS) methods were employed to investigate the aggregations of Pt nanoparticles in three kinds of Pt/C catalysts produced by microwave heating process, soakage-reducing process and glycol synthesis process. The experimental results showed information of characteristic size, surface area and size distributions of Pt nanoparticles and aggregations in three catalysts. The TEM images are in agreement with SAXS conclusions. The investigation showed that the processes affected the characters of Pt nanoparticles and their aggregations in Pt/C catalyst differently. Pt particles produced by microwave heating process scatter uniformly on carbon supports, and have relatively a large surface and sharp size-distribution. Applying the soakage-reducing process and glycol synt
2009,
21.
Abstract:
The three-dimensional model of cubic defect has heen built. 3D finite-difference time-domain method and perfectly matched layer are used. The modulation caused by TM incident laser is simulated while the cubic defect is on the front surface or on the rear surface of fused silica. Sectional electric field intensity distribution and the maximal electric field intensity variance with depth in fused silica are illustrated. The electric fields for materials with a defect on input or output surface have been compared and analyzed. The maximal electric field intensity 2.522 41 V/m near the rear surface is larger than 1.958 83 V/m near the defect when the cubic defect is on the input surface. When the cubic defect is on the output surface, the maximal electric field intensity 2.799 38 V/m in the m
The three-dimensional model of cubic defect has heen built. 3D finite-difference time-domain method and perfectly matched layer are used. The modulation caused by TM incident laser is simulated while the cubic defect is on the front surface or on the rear surface of fused silica. Sectional electric field intensity distribution and the maximal electric field intensity variance with depth in fused silica are illustrated. The electric fields for materials with a defect on input or output surface have been compared and analyzed. The maximal electric field intensity 2.522 41 V/m near the rear surface is larger than 1.958 83 V/m near the defect when the cubic defect is on the input surface. When the cubic defect is on the output surface, the maximal electric field intensity 2.799 38 V/m in the m
2009,
21.
Abstract:
This paper analyzes the localization of traditional sacrificial layer material aluminum and brings forward a new sacrificial layer—ZnO-Al complex sacrificial layer. By means of sputtering to prepare aluminum film and evaporating to prepare zinc-oxide film, field emission arrays are fabricated and then tested. The result indicates that ZnO-Al complex sacrificial layer can solve the problem of electrochemistry, the LaB6 field emission array tips with ZnO-Al layer are in good condition and the array maintains field emission characteristics.
This paper analyzes the localization of traditional sacrificial layer material aluminum and brings forward a new sacrificial layer—ZnO-Al complex sacrificial layer. By means of sputtering to prepare aluminum film and evaporating to prepare zinc-oxide film, field emission arrays are fabricated and then tested. The result indicates that ZnO-Al complex sacrificial layer can solve the problem of electrochemistry, the LaB6 field emission array tips with ZnO-Al layer are in good condition and the array maintains field emission characteristics.
2009,
21.
Abstract:
A series of concentration-varied Tb3+-doped silicate glasses were synthesized by the melt-quenching process. Photoluminescence and radioluminescence of Tb3+-doped silicate glasses were studied under UV and X-ray excitation, respectively. The similar concentration dependence of Tb3+ luminescence on its dopant concentration was obtained under both UV and X-ray excitation. That is, the blue emission (5D3→7FJ) dominates in the case of low concentration Tb3+-doped silicate glass, while the green one (5D4→7FJ) dominates in high concentration doping. The dependence of the intensity on Tb3+-dopant concentration indicates that the quenching of the 5D3 stat
A series of concentration-varied Tb3+-doped silicate glasses were synthesized by the melt-quenching process. Photoluminescence and radioluminescence of Tb3+-doped silicate glasses were studied under UV and X-ray excitation, respectively. The similar concentration dependence of Tb3+ luminescence on its dopant concentration was obtained under both UV and X-ray excitation. That is, the blue emission (5D3→7FJ) dominates in the case of low concentration Tb3+-doped silicate glass, while the green one (5D4→7FJ) dominates in high concentration doping. The dependence of the intensity on Tb3+-dopant concentration indicates that the quenching of the 5D3 stat
2009,
21.
Abstract:
Part of low-earth orbit’s space radiation environment was simulated to investigate the influence on the transmittance change of the aluminum filter used on the space solar telescope in extreme-ultraviolet(EUV) waveband. The transmittance was measured before and after proton irradiation with energy of 100 keV and dose of 6×1011/mm2. And the microstructures of aluminum filter were investigated by transmission electron microscopy(TEM). The experimental results show that the transmittance of filter increases from 12.1% to 15.0% because of the thickness decrease of filter after proton irradiation, and the thickness of the filter beoames inhomogeneous, resulting in the optical performance degradation of the filter and sub-peak in the transmittance curve. The reason is tha
Part of low-earth orbit’s space radiation environment was simulated to investigate the influence on the transmittance change of the aluminum filter used on the space solar telescope in extreme-ultraviolet(EUV) waveband. The transmittance was measured before and after proton irradiation with energy of 100 keV and dose of 6×1011/mm2. And the microstructures of aluminum filter were investigated by transmission electron microscopy(TEM). The experimental results show that the transmittance of filter increases from 12.1% to 15.0% because of the thickness decrease of filter after proton irradiation, and the thickness of the filter beoames inhomogeneous, resulting in the optical performance degradation of the filter and sub-peak in the transmittance curve. The reason is tha
2009,
21.
Abstract:
In this paper, the modulation of light field by the subsurface defects is investigated in detail by solving Maxwell equations employing the finite-difference time-domain method. Meanwhile, the model of three-dimensional defect is set up. Taking cuboid defect as an example, the three-dimensional electromagnetic intensity distribution around the defect is simulated. The maximum electronic field intensity of different defect three dimensional numerical simulation is given. The results show modulation of three-dimensional defect to light intensity is more distinct than that of two-dimensional defect.
In this paper, the modulation of light field by the subsurface defects is investigated in detail by solving Maxwell equations employing the finite-difference time-domain method. Meanwhile, the model of three-dimensional defect is set up. Taking cuboid defect as an example, the three-dimensional electromagnetic intensity distribution around the defect is simulated. The maximum electronic field intensity of different defect three dimensional numerical simulation is given. The results show modulation of three-dimensional defect to light intensity is more distinct than that of two-dimensional defect.
2009,
21.
Abstract:
The choice principle and obtaining method were presented for the trigger signal and surrounding electric-field inspecting signal, based on the characteristics of the radiated-wave electromagnetic pulse(EMP) simulator test and the need of the equipment under test. The test state of equipment was analyzed combining EMP coupling effects and skin effects. The experimental results show that the chosed trigger signal is stable with a large magnitude,and the arrival time of the signal can be calculated accurately. It is suitable to trigger oscilloscopes. The results also indicate that the chosed inspecting signal has a good waveform with a magnitude. It could be the reference for the surveillance and normalization of the variation of surrounding electric-field and other signals．
The choice principle and obtaining method were presented for the trigger signal and surrounding electric-field inspecting signal, based on the characteristics of the radiated-wave electromagnetic pulse(EMP) simulator test and the need of the equipment under test. The test state of equipment was analyzed combining EMP coupling effects and skin effects. The experimental results show that the chosed trigger signal is stable with a large magnitude,and the arrival time of the signal can be calculated accurately. It is suitable to trigger oscilloscopes. The results also indicate that the chosed inspecting signal has a good waveform with a magnitude. It could be the reference for the surveillance and normalization of the variation of surrounding electric-field and other signals．
2009,
21.
Abstract:
Based on the Laplace equation in cylindrical coordinates, coefficient matrix equations of the magnetic field series expression were derived with magnetostatic method for the Tesla transformer. Thus, we obtained the axial magnetic field distributions of the magnetic cores, and the axial and radial magnetic field distributions between the cores. The average coupling coefficient was put forward, which is the average of every single secondary coil’s coefficient. Then we studied the influences of aspect ratio, radius ratio of outer to inner magnetic cores, length ratio of primary winding to magnetic core and relative permeability on the average coefficient. It is found that increasing aspect ratio and decreasing radius ratio are two effective ways to enhance the average coupling coefficient, i
Based on the Laplace equation in cylindrical coordinates, coefficient matrix equations of the magnetic field series expression were derived with magnetostatic method for the Tesla transformer. Thus, we obtained the axial magnetic field distributions of the magnetic cores, and the axial and radial magnetic field distributions between the cores. The average coupling coefficient was put forward, which is the average of every single secondary coil’s coefficient. Then we studied the influences of aspect ratio, radius ratio of outer to inner magnetic cores, length ratio of primary winding to magnetic core and relative permeability on the average coefficient. It is found that increasing aspect ratio and decreasing radius ratio are two effective ways to enhance the average coupling coefficient, i
2009,
21.
Abstract:
A new trigatron with a discal trigger electrode has been tested on its trigger characteristics. And the effects of different polarity combinations, trigger pulse amplitudes and trigger resistances on trigger characteristics of the trigatron have been derived. Then the breakdown mechanism was introduced to explain the results. It is found that the optimum polarity combination is heteropolarity and the best scope of the ratio between trigger voltage and self-breakdown voltage is 30%~50%. The appropriate trigger resistance is 50~100 Ω to achieve large current considering the safety operation of the trigatron.
A new trigatron with a discal trigger electrode has been tested on its trigger characteristics. And the effects of different polarity combinations, trigger pulse amplitudes and trigger resistances on trigger characteristics of the trigatron have been derived. Then the breakdown mechanism was introduced to explain the results. It is found that the optimum polarity combination is heteropolarity and the best scope of the ratio between trigger voltage and self-breakdown voltage is 30%~50%. The appropriate trigger resistance is 50~100 Ω to achieve large current considering the safety operation of the trigatron.
2009,
21.
Abstract:
The two-electrode switch has no trigger electrode and longer life than the three-electrode switch. In order to trigger the switch, the trigger voltage’s peak-to-peak value should be very high and the rise time of trigger pulse should be short. This paper introduces a kind of trigger system which uses a 8-step Marx generator. The trigger system includes the Marx generator, power switch, insulating transformer, L-C charging circuit, sampling control circuit, optical fiber control circuit and triggering circuit. In order to reduce the inductance of Marx generator discharge circuit, the Marx generator uses low-inductance capacitors and coaxial structure. The trigger voltage is 120 kV, and the rise time is less than 30 ns. The simulation mode of the Marx generator discharge circuit is establi
The two-electrode switch has no trigger electrode and longer life than the three-electrode switch. In order to trigger the switch, the trigger voltage’s peak-to-peak value should be very high and the rise time of trigger pulse should be short. This paper introduces a kind of trigger system which uses a 8-step Marx generator. The trigger system includes the Marx generator, power switch, insulating transformer, L-C charging circuit, sampling control circuit, optical fiber control circuit and triggering circuit. In order to reduce the inductance of Marx generator discharge circuit, the Marx generator uses low-inductance capacitors and coaxial structure. The trigger voltage is 120 kV, and the rise time is less than 30 ns. The simulation mode of the Marx generator discharge circuit is establi
2009,
21.
Abstract:
Increasing importance is being placed on the compact and lightweight repetitive high power nanosecond pulse generator. Based on the ceramic capacitor with neglectable self-inductance, a new high energy density pulse forming module which can form low impedance pulse easily has been developed. The mid-high voltage pulses provide by the modules are used tp produce the demanding high voltage by inductive voltage adding. The experimental results indicate that the rise time of the mid-high voltage pulse generated by single linear transformer driver(LTD) cell is about 50 ns and the pulse width is about 220 ns when the matching load is 2.8 Ω．
Increasing importance is being placed on the compact and lightweight repetitive high power nanosecond pulse generator. Based on the ceramic capacitor with neglectable self-inductance, a new high energy density pulse forming module which can form low impedance pulse easily has been developed. The mid-high voltage pulses provide by the modules are used tp produce the demanding high voltage by inductive voltage adding. The experimental results indicate that the rise time of the mid-high voltage pulse generated by single linear transformer driver(LTD) cell is about 50 ns and the pulse width is about 220 ns when the matching load is 2.8 Ω．
