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RSS2001 Vol. 13, No. 05
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2001,
13.
Abstract:
A experimental method, Pressure Loading by Steps, is designed to measure the fracture and buckling failure pressures of hollow glass microspheres(HGM) for use in laser fusion experiments. The failure pressures of 3 kinds of HGM with out-diameters of 350m m～550m m and wall-thickness less than 1.1m m and their glass’s elastic moduli and tensile strengthes are measured experimentally. From the results, experimental formulae are obtained to evaluate the failure pressures of HGM in different out-diameter and wall-thickness without any test. Moreover, the experimental error sources and ways to improve them are discussed.
A experimental method, Pressure Loading by Steps, is designed to measure the fracture and buckling failure pressures of hollow glass microspheres(HGM) for use in laser fusion experiments. The failure pressures of 3 kinds of HGM with out-diameters of 350m m～550m m and wall-thickness less than 1.1m m and their glass’s elastic moduli and tensile strengthes are measured experimentally. From the results, experimental formulae are obtained to evaluate the failure pressures of HGM in different out-diameter and wall-thickness without any test. Moreover, the experimental error sources and ways to improve them are discussed.
2001,
13.
Abstract:
Preparation of low-density poly (4-methyl-1-pentene) foam (pmp foam) is described. The thermal analysis method is utilized to measure on line the gelation of pmp polymer in the binary solvent/nonsolvent (durene/naphthalene) system. The range of gelation temperature is preliminarily determined. The influence of mixture system composition and the cooling rate during the making of foams is discussed. TG-DSC is applied to determine the thermal properties of low-density pmp foams. And the effect of density’s change on the thermal stability of foams has been studied. These thermal analysis data play a great role in improving the foam quality.
Preparation of low-density poly (4-methyl-1-pentene) foam (pmp foam) is described. The thermal analysis method is utilized to measure on line the gelation of pmp polymer in the binary solvent/nonsolvent (durene/naphthalene) system. The range of gelation temperature is preliminarily determined. The influence of mixture system composition and the cooling rate during the making of foams is discussed. TG-DSC is applied to determine the thermal properties of low-density pmp foams. And the effect of density’s change on the thermal stability of foams has been studied. These thermal analysis data play a great role in improving the foam quality.
2001,
13.
Abstract:
The direct implosion experiments, in which the grass microballoons were filled with DT fuel , are very successful at Shenguang II laser facility in 2000. One of ways to measure the fusion neutron yield is the 63Cu activation .The principle of the Cu activation, g - g coincidence counting system, its software structure and function, and calibration are presented in this report. After the counting order of the radiated sample counting, saving, data analyzing and treatment, printing of the result and so on are all controlled by the computer, so that the reliability and working efficiency are improved.
The direct implosion experiments, in which the grass microballoons were filled with DT fuel , are very successful at Shenguang II laser facility in 2000. One of ways to measure the fusion neutron yield is the 63Cu activation .The principle of the Cu activation, g - g coincidence counting system, its software structure and function, and calibration are presented in this report. After the counting order of the radiated sample counting, saving, data analyzing and treatment, printing of the result and so on are all controlled by the computer, so that the reliability and working efficiency are improved.
2001,
13.
Abstract:
The characteristics and fabrication techniques of z-pinch targets including loads and their related materials are reviewed in this paper. The Z-pinch targets are classified into three kinds as vacuum hohlraum , dynamic hohlraum and static-wall hohlraum. And the configurations and applications of these kinds of targets are introduced, respectively. Furthermore, the features of z-pinch targets are compared with those of laser inertial confinement fusion targets. In order to meet the demands of z-pinch physical experiments in China, an assembling process is proposed to fabricate a z-pinch wire array load, which involves the pretreatment and preparation of wires and the characterizing of wires and the machining of fixture embryos and the assembly of wire array.
The characteristics and fabrication techniques of z-pinch targets including loads and their related materials are reviewed in this paper. The Z-pinch targets are classified into three kinds as vacuum hohlraum , dynamic hohlraum and static-wall hohlraum. And the configurations and applications of these kinds of targets are introduced, respectively. Furthermore, the features of z-pinch targets are compared with those of laser inertial confinement fusion targets. In order to meet the demands of z-pinch physical experiments in China, an assembling process is proposed to fabricate a z-pinch wire array load, which involves the pretreatment and preparation of wires and the characterizing of wires and the machining of fixture embryos and the assembly of wire array.
2001,
13.
Abstract:
A 2-1/2D cylindrical full electromagnetic particle-in-cell code is used to simulate erosion phenomena of a high-density plasma opening switch. The computational model involving complex boundaries has been briefly introduced. The simulation results show that at the end of the conduction phase a vacuum sheath will form near a cathode, the formation mechanisms include deformation of plasma by magnetic pressure, the penetration of magnetic field and electrostatic erosion. Because of the descent of the plasma density and the existence of vacuum sheath, plasma opening switch can be opened by erosion mechanism on the condition of smaller ion current density.
A 2-1/2D cylindrical full electromagnetic particle-in-cell code is used to simulate erosion phenomena of a high-density plasma opening switch. The computational model involving complex boundaries has been briefly introduced. The simulation results show that at the end of the conduction phase a vacuum sheath will form near a cathode, the formation mechanisms include deformation of plasma by magnetic pressure, the penetration of magnetic field and electrostatic erosion. Because of the descent of the plasma density and the existence of vacuum sheath, plasma opening switch can be opened by erosion mechanism on the condition of smaller ion current density.
2001,
13.
Abstract:
The design of a four-channel gated integrator system based on VXI bus containing functional circuit and interface circuit is introduced. From the VXI bus, it is a registered device in which there are configure registers and operational registers. This module is used to integrate the output current of X-ray diodes. The software of the data acquisition (DAQ) system, which has characters of “virtual instrumentation”, is also introduced. On electronic test, the system has good performance.: The gate width in which the current is integrated is 10-12ns, integral nonlinearity is less than 1% and there is hardly interference between channels. The maximum error between the results of this module and of oscilloscope is less than 2% of the scale range of the gated integrators. Through these tests,
The design of a four-channel gated integrator system based on VXI bus containing functional circuit and interface circuit is introduced. From the VXI bus, it is a registered device in which there are configure registers and operational registers. This module is used to integrate the output current of X-ray diodes. The software of the data acquisition (DAQ) system, which has characters of “virtual instrumentation”, is also introduced. On electronic test, the system has good performance.: The gate width in which the current is integrated is 10-12ns, integral nonlinearity is less than 1% and there is hardly interference between channels. The maximum error between the results of this module and of oscilloscope is less than 2% of the scale range of the gated integrators. Through these tests,
2001,
13.
Abstract:
Pulsed laser-induced bulk damage of UBK7 glass at 1064nm was studied. Damage morphologies of UBK7 were observed with a microscope. Laser-induced damage thresholds (LIDT) of the glass's surface and bulk were tested using automated damage test facility. Thread damage between rear-surface and bulk burst was detected from the damage morphologies. The conclusion that defects and impurities on the rear-surface caused bulk damage was drawn. When the defects on rear-surface absorb incident light, plasma was produced and it spread to the front rapidly. Then the high temperature and high pressure of the plasma caused surface and bulk damage of the material. The details o f surface and bulk damage mechanism were also analyzed. The LIDT of rear-surface is lower than that of front-surface because of th
Pulsed laser-induced bulk damage of UBK7 glass at 1064nm was studied. Damage morphologies of UBK7 were observed with a microscope. Laser-induced damage thresholds (LIDT) of the glass's surface and bulk were tested using automated damage test facility. Thread damage between rear-surface and bulk burst was detected from the damage morphologies. The conclusion that defects and impurities on the rear-surface caused bulk damage was drawn. When the defects on rear-surface absorb incident light, plasma was produced and it spread to the front rapidly. Then the high temperature and high pressure of the plasma caused surface and bulk damage of the material. The details o f surface and bulk damage mechanism were also analyzed. The LIDT of rear-surface is lower than that of front-surface because of th
2001,
13.
Abstract:
Improved double disk targets are used to investigate X-ray re-emission from gold material heated by radiation. The primary disk is an oblique cylinder cavity. X-ray radiation emitted from the Au foil in the rear of the cavity ablates secondary Au disk. Thus plasma expan sion's effect of primary disk on secondary disk is reduced, and then the X-ray radiation ablating secondary disk is “pure and clear”. An X-ray streak camera is used to measure time-space images of double disk targets. Two soft X-ray spectrometers are used to measure X-ray spectra of primary and secondary disk respectively. The property that X-ray spectra were modified on secondary disk is investigated. The measured results show that the improved double disk targets can basically avoid plasma expansion's effect from primar
Improved double disk targets are used to investigate X-ray re-emission from gold material heated by radiation. The primary disk is an oblique cylinder cavity. X-ray radiation emitted from the Au foil in the rear of the cavity ablates secondary Au disk. Thus plasma expan sion's effect of primary disk on secondary disk is reduced, and then the X-ray radiation ablating secondary disk is “pure and clear”. An X-ray streak camera is used to measure time-space images of double disk targets. Two soft X-ray spectrometers are used to measure X-ray spectra of primary and secondary disk respectively. The property that X-ray spectra were modified on secondary disk is investigated. The measured results show that the improved double disk targets can basically avoid plasma expansion's effect from primar
2001,
13.
Abstract:
The width and shift of the Al X resonance line 2s2 1S-2s2p1P0 were calculated using R-matrix method and semi-empirical method. Good agreement was found between the two calculations. The semi-empirical method can easily obtain large numbers of widths and there fore can be applied to derive the opacity of plasmas using detailed-term-accounting-approximation calculations. Some other widths of Al X lines were also obtained using the semi-empirical method. Detailed-term-accounting model can obtain accurate opacities of high temperature plasmas, but it requires large number s of atomic parameters such as excitation energies, oscillator strengths and widths of dipole allowed transitions. The results presented in this paper show that the calculations of the electron impact broadening can be greatl
The width and shift of the Al X resonance line 2s2 1S-2s2p1P0 were calculated using R-matrix method and semi-empirical method. Good agreement was found between the two calculations. The semi-empirical method can easily obtain large numbers of widths and there fore can be applied to derive the opacity of plasmas using detailed-term-accounting-approximation calculations. Some other widths of Al X lines were also obtained using the semi-empirical method. Detailed-term-accounting model can obtain accurate opacities of high temperature plasmas, but it requires large number s of atomic parameters such as excitation energies, oscillator strengths and widths of dipole allowed transitions. The results presented in this paper show that the calculations of the electron impact broadening can be greatl
2001,
13.
Abstract:
Functional Gradiently Material is a very important branch in the field of material research and application. In this paper, the Cu2O/C60 gradient films have been produced on quartz substrate using vacuum deposition system with Cu2O and C60 source. The surf ace configuration, the distribution of component and the UV-VIS absorption were measured by AFM, XPS and UV-VIS spectrum instrument. The result shows that the films descripted in this paper conform the law of the gradient films.
Functional Gradiently Material is a very important branch in the field of material research and application. In this paper, the Cu2O/C60 gradient films have been produced on quartz substrate using vacuum deposition system with Cu2O and C60 source. The surf ace configuration, the distribution of component and the UV-VIS absorption were measured by AFM, XPS and UV-VIS spectrum instrument. The result shows that the films descripted in this paper conform the law of the gradient films.
2001,
13.
Abstract:
In this paper, the precise design of the diffractive optical element (DOE) is completed to control the shape of t he focused spot. By using the hybrid algorithm, merging Hill-climbing with Simulated Annealing, and adjusting the weight factor in the optimization, the DOE can realize high uniformity at the main lobe (non-uniformity is less than 10%) and no "blocking" effect around the hole (the ratio between the peak intensity around the hole and the average value of the main lobe is less than 0.01%) simultaneously. Different sampling intervals are used to examine the performance of the DOE, and the simulated results show that the calculated performance parameters are true and accurate with the precise design, and the fence effect induced by discretization with the traditional sampling inter
In this paper, the precise design of the diffractive optical element (DOE) is completed to control the shape of t he focused spot. By using the hybrid algorithm, merging Hill-climbing with Simulated Annealing, and adjusting the weight factor in the optimization, the DOE can realize high uniformity at the main lobe (non-uniformity is less than 10%) and no "blocking" effect around the hole (the ratio between the peak intensity around the hole and the average value of the main lobe is less than 0.01%) simultaneously. Different sampling intervals are used to examine the performance of the DOE, and the simulated results show that the calculated performance parameters are true and accurate with the precise design, and the fence effect induced by discretization with the traditional sampling inter
2001,
13.
Abstract:
An antenna was developed to radiate high power, sub-nanosecond EM pulse, which consists of a high power wideband mode convertor, a wire frame TEM horn feedback set and a parabolic reflector. The radiation E field pattern is about ±3.8°and radiation efficiency is 37% when the antenna is execited by a pulse of 700ps duration and 200kV peak voltage. Compared with those antennas with face-to-face TEM horns or co-planar TEM horns, this kind of antenna has the best radiating property.
An antenna was developed to radiate high power, sub-nanosecond EM pulse, which consists of a high power wideband mode convertor, a wire frame TEM horn feedback set and a parabolic reflector. The radiation E field pattern is about ±3.8°and radiation efficiency is 37% when the antenna is execited by a pulse of 700ps duration and 200kV peak voltage. Compared with those antennas with face-to-face TEM horns or co-planar TEM horns, this kind of antenna has the best radiating property.
2001,
13.
Abstract:
Intense electromagnetic pulse，namely nucleus electromagnetic pulse(NEMP)， lightning electromagnetic pulse(LEMP) and high power microwave(HPM), can disturb and destroy the single chip computer system. To study this issue, we made irradiation experiments by NEMPs generated by gigahertz transversal electromagnetic(GTEM) Cell. The experiments show that shutdown, restarting, communication errors of the single chip microcomputer system would occur when it was irradiated by the NEMPs. Based on the experiments, the cause on the effects on the single chip microcomputer system is discused.
Intense electromagnetic pulse，namely nucleus electromagnetic pulse(NEMP)， lightning electromagnetic pulse(LEMP) and high power microwave(HPM), can disturb and destroy the single chip computer system. To study this issue, we made irradiation experiments by NEMPs generated by gigahertz transversal electromagnetic(GTEM) Cell. The experiments show that shutdown, restarting, communication errors of the single chip microcomputer system would occur when it was irradiated by the NEMPs. Based on the experiments, the cause on the effects on the single chip microcomputer system is discused.
2001,
13.
Abstract:
The relativistic two-stream amplifier (RTSA) is a kind of high power microwave device with simple geometrical structure and high efficiency. Its working mechanism is the two-stream instability between the two concentric circular beams, which propagates through the waveguide along the same direction. This two-stream instability generates the energy exchange between the electron beams. Pumped by the output cavity, the energy of electron beams generates the microwave power amplification. The microwave is input by the cavity of RTSA. It is critical issue to generate such two electron beams to be emitted into the waveguide. By using the MAGIC PIC simulation program. The formation of electron beams in RTSA is simulated and some of the key parameters is got. The results show that it is available
The relativistic two-stream amplifier (RTSA) is a kind of high power microwave device with simple geometrical structure and high efficiency. Its working mechanism is the two-stream instability between the two concentric circular beams, which propagates through the waveguide along the same direction. This two-stream instability generates the energy exchange between the electron beams. Pumped by the output cavity, the energy of electron beams generates the microwave power amplification. The microwave is input by the cavity of RTSA. It is critical issue to generate such two electron beams to be emitted into the waveguide. By using the MAGIC PIC simulation program. The formation of electron beams in RTSA is simulated and some of the key parameters is got. The results show that it is available
2001,
13.
Abstract:
The development of high-current, short-duration pulses of electrons has been a challenging problem for many years. Micro-pulse-gun (MPG) is a novel concept that employs the resonant amplification of an electron current by secondary electron emission in a RF cavity. Using the computation code URMEL-T, several kinds of RF cavity under the frequency of 2856MHz were calculated and optimized, the magnetic and electric field distribution in them were got. Through particle-in-cell (PIC) simulation, the self-bunching process in a MPG was proved, the relation between the cavity length and selected phase and the relation between the peak electric field and selected phase were got. With cathode material of high secondary emission coefficient, the MPG can produce high current densities (1132~5303A/cm2
The development of high-current, short-duration pulses of electrons has been a challenging problem for many years. Micro-pulse-gun (MPG) is a novel concept that employs the resonant amplification of an electron current by secondary electron emission in a RF cavity. Using the computation code URMEL-T, several kinds of RF cavity under the frequency of 2856MHz were calculated and optimized, the magnetic and electric field distribution in them were got. Through particle-in-cell (PIC) simulation, the self-bunching process in a MPG was proved, the relation between the cavity length and selected phase and the relation between the peak electric field and selected phase were got. With cathode material of high secondary emission coefficient, the MPG can produce high current densities (1132~5303A/cm2
2001,
13.
Abstract:
A new method of single-shot measurement of normal incidence soft x-ray Mo/Si multilayer mirror’s reflectance is proposed, experiment has been performed using laser-produced plasma x-ray source, flat field grating spectrometer, soft x-ray CCD. Grazing incident mirror was employed to eliminate high-order contribution. Reflectance of Mo/Si multi-layer mirror with a 13.9 nm designed center wavelength is measured in one laser shot.
A new method of single-shot measurement of normal incidence soft x-ray Mo/Si multilayer mirror’s reflectance is proposed, experiment has been performed using laser-produced plasma x-ray source, flat field grating spectrometer, soft x-ray CCD. Grazing incident mirror was employed to eliminate high-order contribution. Reflectance of Mo/Si multi-layer mirror with a 13.9 nm designed center wavelength is measured in one laser shot.
2001,
13.
Abstract:
In the application of high-power lasers, damage of coating multilayers of laser systems mainly limits the laser performance, so there is great interest in reducing the susceptibility of optical coating damage. In this paper, defects of HfO2/SiO2 high reflected coatings and their laser damage have been studied in details. The coating samples were deposited by e-beam evaporation onto K9 glass substrates using hafnia-silica materials. The defects and damage morphologies of coating were observed and analyzed by AFM, Normaski and SEM microscopes. In damage experiment, it was found that the coating onset damage is mainly caused by nodular defect. The laser energy density for damaging the pits, flat bottom pits etc is more three times than that for damaging nodular(about 15J/cm2). The size and it
In the application of high-power lasers, damage of coating multilayers of laser systems mainly limits the laser performance, so there is great interest in reducing the susceptibility of optical coating damage. In this paper, defects of HfO2/SiO2 high reflected coatings and their laser damage have been studied in details. The coating samples were deposited by e-beam evaporation onto K9 glass substrates using hafnia-silica materials. The defects and damage morphologies of coating were observed and analyzed by AFM, Normaski and SEM microscopes. In damage experiment, it was found that the coating onset damage is mainly caused by nodular defect. The laser energy density for damaging the pits, flat bottom pits etc is more three times than that for damaging nodular(about 15J/cm2). The size and it
2001,
13.
Abstract:
Propagation properties of decentered Hermite-Gaussian beams through misaligned first-order optical systems are studied by using the generalized Huygens-Fresnel diffraction integral, augmented matrix and Wigner distribution function methods. It is shown that, as a decentered Hermite-Gaussian beam passes through the misaligned first-order optical system, the closed property is preserved, the second-order moments matrix varies with the usual law, the beam propagation factor remains unchanged, the first order moments matrix evolves, as if it were a ray of geometrical optics.
Propagation properties of decentered Hermite-Gaussian beams through misaligned first-order optical systems are studied by using the generalized Huygens-Fresnel diffraction integral, augmented matrix and Wigner distribution function methods. It is shown that, as a decentered Hermite-Gaussian beam passes through the misaligned first-order optical system, the closed property is preserved, the second-order moments matrix varies with the usual law, the beam propagation factor remains unchanged, the first order moments matrix evolves, as if it were a ray of geometrical optics.
2001,
13.
Abstract:
Because of obvious difference between expanding light source and laser source, it appears different scattering peculiarity while they project to a random rough cylinder. In this paper, the random facet model is employed to establish the rough cylinder scattering theory，which is used to calculate the intensity distributions of the scattered laser from random rough cylinder surfaces, and this provides useful model for the most engineering design.
Because of obvious difference between expanding light source and laser source, it appears different scattering peculiarity while they project to a random rough cylinder. In this paper, the random facet model is employed to establish the rough cylinder scattering theory，which is used to calculate the intensity distributions of the scattered laser from random rough cylinder surfaces, and this provides useful model for the most engineering design.
2001,
13.
Abstract:
In this paper a water cooler for 2D laser diode arrays cooling was presented. The cooler can be manufactured with line cutting method and with very low cost. The thermal resistance of the laser diode with back cooling packaged structure was calculated and the thickness of the submount and the structure of the cooler were optimized by three-dimension finite element method. The calculated results indicated that the thickness of submount, the cooling water channel depth and the fin width have optimum values. The lowest thermal impedance of the water cooler was 0.093℃·cm2/W. The pack age design can meet the needs of heat dissipating for high power laser diode arrays with power density of 500W/cm2 and 20% duty cycle.
In this paper a water cooler for 2D laser diode arrays cooling was presented. The cooler can be manufactured with line cutting method and with very low cost. The thermal resistance of the laser diode with back cooling packaged structure was calculated and the thickness of the submount and the structure of the cooler were optimized by three-dimension finite element method. The calculated results indicated that the thickness of submount, the cooling water channel depth and the fin width have optimum values. The lowest thermal impedance of the water cooler was 0.093℃·cm2/W. The pack age design can meet the needs of heat dissipating for high power laser diode arrays with power density of 500W/cm2 and 20% duty cycle.
2001,
13.
Abstract:
A spontaneous Raman imaging system has been described that can monitor the concentrations of major species in flow field in real time. We present the results of the species in the air with a doubled Nd:YAG laser and a single intensified CCD array at the exit of an imaging spectrograph. The output laser energy and the position of the measurement point have effect on the precision. The error is calculated to be less than 8%. The measurement precision of O2（a1Δ） concentration will be improved largely when this technique is applied to monitor chemical oxygen-iodine laser singlet oxygen generator performance.
A spontaneous Raman imaging system has been described that can monitor the concentrations of major species in flow field in real time. We present the results of the species in the air with a doubled Nd:YAG laser and a single intensified CCD array at the exit of an imaging spectrograph. The output laser energy and the position of the measurement point have effect on the precision. The error is calculated to be less than 8%. The measurement precision of O2（a1Δ） concentration will be improved largely when this technique is applied to monitor chemical oxygen-iodine laser singlet oxygen generator performance.
2001,
13.
Abstract:
In this paper, a mathematical model for quantitatively analyzing Shack-Hartmann wavefront sensor(S-H WFS)'s detecting error under realistic atmospheric turbulence is presented, and the transfer characteristics of a variety of detecting error are researched. Results show that the S-H WFS's detecting errors will increase due to the atmospheric scintillation, sky background radiation and so on when Shack-Hartmann wavefront sensor is used in probing very low light level beacon, and along with the decrease of the contrast between the beacon and the sky background, the centroid detecting error goes up while the aperture input fluctuates more strongly.
In this paper, a mathematical model for quantitatively analyzing Shack-Hartmann wavefront sensor(S-H WFS)'s detecting error under realistic atmospheric turbulence is presented, and the transfer characteristics of a variety of detecting error are researched. Results show that the S-H WFS's detecting errors will increase due to the atmospheric scintillation, sky background radiation and so on when Shack-Hartmann wavefront sensor is used in probing very low light level beacon, and along with the decrease of the contrast between the beacon and the sky background, the centroid detecting error goes up while the aperture input fluctuates more strongly.
2001,
13.
Abstract:
The concept of integral calibration for the transmission grating spectrometer is suggested. Compared with other calibration method, the integral calibration method is more convenient and valid, and its data process is simpler. Also, the calibration results can be more directly used. The calibrated experiments were first carried out on Beijing Synchrotron Radiation Facility (BSRF). The experimental results agree well with the calibrated results for transmission grating spectrometer and X-ray CCD separately.
The concept of integral calibration for the transmission grating spectrometer is suggested. Compared with other calibration method, the integral calibration method is more convenient and valid, and its data process is simpler. Also, the calibration results can be more directly used. The calibrated experiments were first carried out on Beijing Synchrotron Radiation Facility (BSRF). The experimental results agree well with the calibrated results for transmission grating spectrometer and X-ray CCD separately.
2001,
13.
Abstract:
Amplitude scintillation affects adaptive optics correction seriously when laser propagates long distances nearly horizontally in atmosphere. Field correction can be fulfilled with two-deformable-mirror adaptive optics. The result of correction is affected by the choice of beacon wavelength. Expressions of field variance and beacon wavelength for phase and field compensations are derived by Rytov approximation. The calculated results show that when the ratio of beacon wavelength to main laser wavelength is less than 1.89, field variance of full field compensation is less than that of phase compensation.
Amplitude scintillation affects adaptive optics correction seriously when laser propagates long distances nearly horizontally in atmosphere. Field correction can be fulfilled with two-deformable-mirror adaptive optics. The result of correction is affected by the choice of beacon wavelength. Expressions of field variance and beacon wavelength for phase and field compensations are derived by Rytov approximation. The calculated results show that when the ratio of beacon wavelength to main laser wavelength is less than 1.89, field variance of full field compensation is less than that of phase compensation.
2001,
13.
Abstract:
Powering solid state lasers and accelerators with compulsator is a novel technology, which could reach high average beam power for wide industry applications. As shown in the paper, the novel route is emerging due to successfully lasering experiments driven by the compulsators. It has merits of high specific power and energy storage，reliability，high rates of pulse repetition and long life. The specific power and energy storage of all possible pulsed powers are listed and compared. The theory of flux compression and the two stage amplification of the cascade compulsator are explained. The principles of self-exciting and two devices in one shell in the system of cascade compulsators are explained. The basic design equations, the design and experimental results of a 10MW cascade compulsator
Powering solid state lasers and accelerators with compulsator is a novel technology, which could reach high average beam power for wide industry applications. As shown in the paper, the novel route is emerging due to successfully lasering experiments driven by the compulsators. It has merits of high specific power and energy storage，reliability，high rates of pulse repetition and long life. The specific power and energy storage of all possible pulsed powers are listed and compared. The theory of flux compression and the two stage amplification of the cascade compulsator are explained. The principles of self-exciting and two devices in one shell in the system of cascade compulsators are explained. The basic design equations, the design and experimental results of a 10MW cascade compulsator
Electric field fit and error calculation of the calibration system of BPMs for HLS injection system
2001,
13.
Abstract:
This paper describes the calibration of the newly manufactured BPMs developed for injection system upgrade in NSRL phase II project, as well as the electrical field fitting and error calculation. The antenna calibration system employs an equipment whose precision adjusted to 10m m and with vertical vacuum pipelines, and a signal processor with 1m m of resolution and working in RF of NSRL ring. The fitting error of the electric field is presented. With the calibrating system and processing method which has a system error about ± 15m m and the precision of 1m m, we have completed the calibration and quality checking of the developed equipment. Due t o the vertically fixed beam pipe and the antenna's movement to simulate beam orb it deviation, as well as the adoption of the RF CW to simulate
This paper describes the calibration of the newly manufactured BPMs developed for injection system upgrade in NSRL phase II project, as well as the electrical field fitting and error calculation. The antenna calibration system employs an equipment whose precision adjusted to 10m m and with vertical vacuum pipelines, and a signal processor with 1m m of resolution and working in RF of NSRL ring. The fitting error of the electric field is presented. With the calibrating system and processing method which has a system error about ± 15m m and the precision of 1m m, we have completed the calibration and quality checking of the developed equipment. Due t o the vertically fixed beam pipe and the antenna's movement to simulate beam orb it deviation, as well as the adoption of the RF CW to simulate
2001,
13.
Abstract:
The dispersion equation on a cylindrical waveguide having an annular plasma sheet is derived under the condition of limited magnetic field. The different plasma density, thickness, and field in tensity influence to the plasma frequency, especially the influences of plasma thickness on depressive characteristics and interaction growth rate are discussed, and the conclusion is obtained that there is a perfect thickness to get the biggest interaction rate.
The dispersion equation on a cylindrical waveguide having an annular plasma sheet is derived under the condition of limited magnetic field. The different plasma density, thickness, and field in tensity influence to the plasma frequency, especially the influences of plasma thickness on depressive characteristics and interaction growth rate are discussed, and the conclusion is obtained that there is a perfect thickness to get the biggest interaction rate.
2001,
13.
Abstract:
The calculations of the rate coefficients for dielectronic recombination (DR) along the NiI isoelectronic sequence in the ground state Gd36+ through Cu-like inner-shell excited configurations were performed using the model of SOSA. Collisional transitions following electron capture are neglected. The trend of the DR rate coefficients was founded with the change of the electronic temperature in the range of (0.02~5)keV .The main factor which effected the DR coefficients was analyzed. This is the relative auto-ionization coefficients and auto-ionized energy. These will provide a new method for diagnose the parameters.
The calculations of the rate coefficients for dielectronic recombination (DR) along the NiI isoelectronic sequence in the ground state Gd36+ through Cu-like inner-shell excited configurations were performed using the model of SOSA. Collisional transitions following electron capture are neglected. The trend of the DR rate coefficients was founded with the change of the electronic temperature in the range of (0.02~5)keV .The main factor which effected the DR coefficients was analyzed. This is the relative auto-ionization coefficients and auto-ionized energy. These will provide a new method for diagnose the parameters.
2001,
13.
Abstract:
The prototypes of high precision solenoid coils in electron cooling device were fabricated by special techniques. Two coils were placed in two parallel, concentric planes, the lower coil was fixed, and the upper coil can be rotated concentrically. The transverse component of magnetic field in coils was measured with the high resolution Hall sensor, The deviation between magnetic axis of coils and geometric axis of reference plane was less than 1 10-3 after adjustment.
The prototypes of high precision solenoid coils in electron cooling device were fabricated by special techniques. Two coils were placed in two parallel, concentric planes, the lower coil was fixed, and the upper coil can be rotated concentrically. The transverse component of magnetic field in coils was measured with the high resolution Hall sensor, The deviation between magnetic axis of coils and geometric axis of reference plane was less than 1 10-3 after adjustment.
2001,
13.
Abstract:
The forming and drifting of plasma in the intense electron beam diode is one of the important issues in studying the diode's operation. In this paper, based on the Child-Langmuir law and conduction coefficient of the cool-cathode diode, it is suppose that the cathode emission area of intense electron beam diode is variable. The drift velocity of the plasma in the diode is studied with experimental data of FLASH-Ⅱ accelerator. The result shows that the drift velocity of plasma is variable with time. The qualitative analysis about this velocity presents the closing speed of the gap between the diode's two poles and also fully explains the plasma's movement while the diode is on.
The forming and drifting of plasma in the intense electron beam diode is one of the important issues in studying the diode's operation. In this paper, based on the Child-Langmuir law and conduction coefficient of the cool-cathode diode, it is suppose that the cathode emission area of intense electron beam diode is variable. The drift velocity of the plasma in the diode is studied with experimental data of FLASH-Ⅱ accelerator. The result shows that the drift velocity of plasma is variable with time. The qualitative analysis about this velocity presents the closing speed of the gap between the diode's two poles and also fully explains the plasma's movement while the diode is on.
2001,
13.
Abstract:
The analytic formulary relations hips between current and voltage in inward-emitting coaxial diode are presented in this paper as well as the PIC numerical simulation and experim ental verification. Due to the 2-D effects, the analytic formulary can't exactly describe the characteristic of the current-voltage relationships in the diode. Hence, a numerical simulation code-KARAT is employed to study the 2-D effect s modification of this relation in different diode voltage level, and the modification coefficient vs. Different parameters are given. The intuitionistic pictures of the electron motion in the diode are also obtained. Meanwhile, the self-pinched current of inward-emitting coaxial diode is deduced. The experiment of coaxial diode was carried out on the SINUS-881 accelerator, and the
The analytic formulary relations hips between current and voltage in inward-emitting coaxial diode are presented in this paper as well as the PIC numerical simulation and experim ental verification. Due to the 2-D effects, the analytic formulary can't exactly describe the characteristic of the current-voltage relationships in the diode. Hence, a numerical simulation code-KARAT is employed to study the 2-D effect s modification of this relation in different diode voltage level, and the modification coefficient vs. Different parameters are given. The intuitionistic pictures of the electron motion in the diode are also obtained. Meanwhile, the self-pinched current of inward-emitting coaxial diode is deduced. The experiment of coaxial diode was carried out on the SINUS-881 accelerator, and the
2001,
13.
Abstract:
The application of CT can supply a new method of diagnosing beam independent of the beam model. By using this technology a precise two dimensions transverse-phase-space density(2D-TPSD) satisfying for a variety of applications could be obtained. This paper presents a code for the iteration rebuild algorithm (ART) of the method. As an example, the 2D-TPSD image by using this method was obtained. It is proved t hat this method could improve the measuring precision of the beam emittance that will provide a new checking for transport beam theories and beam dynamic theor ies.
The application of CT can supply a new method of diagnosing beam independent of the beam model. By using this technology a precise two dimensions transverse-phase-space density(2D-TPSD) satisfying for a variety of applications could be obtained. This paper presents a code for the iteration rebuild algorithm (ART) of the method. As an example, the 2D-TPSD image by using this method was obtained. It is proved t hat this method could improve the measuring precision of the beam emittance that will provide a new checking for transport beam theories and beam dynamic theor ies.
