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RSS1996 Vol. 08, No. 01
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1996,
08.
Abstract:
The optimum pressure of gas in the IREB transported chamber under an externally applied magnetic guide field is studied theoretically and experimentally in this paper. Ionization by electron avalanching and by beam electrons impact and recombination is included in the calculation of plasma density and plasma current build up. The calculations demonstrate that the optimum gas pressure increases as peak beam current, and it decreases as the risetime of beam pulse increases. The optimum nitrogen pressure is about 332Pa, when the peak beam current is 500kA, the peak voltage is 1.0MV, and the risetime of beam pulse is 60ns, showing that the net current and the time average of electric field are minimum when the gas pressure is about 332Pa, the window of nitrogen pressure for the beam transport
The optimum pressure of gas in the IREB transported chamber under an externally applied magnetic guide field is studied theoretically and experimentally in this paper. Ionization by electron avalanching and by beam electrons impact and recombination is included in the calculation of plasma density and plasma current build up. The calculations demonstrate that the optimum gas pressure increases as peak beam current, and it decreases as the risetime of beam pulse increases. The optimum nitrogen pressure is about 332Pa, when the peak beam current is 500kA, the peak voltage is 1.0MV, and the risetime of beam pulse is 60ns, showing that the net current and the time average of electric field are minimum when the gas pressure is about 332Pa, the window of nitrogen pressure for the beam transport
1996,
08.
Abstract:
The fabrication of X 杛ay laser germanium film targets is presented in this paper. The 30~ 60ns thickness germanium film was coated on the 90nm thickness formvar film by using radio 杅requency magnetron sputtering technology. The germanium film targets accord with the demands of experiments by Leitz interference microscope measurement.
The fabrication of X 杛ay laser germanium film targets is presented in this paper. The 30~ 60ns thickness germanium film was coated on the 90nm thickness formvar film by using radio 杅requency magnetron sputtering technology. The germanium film targets accord with the demands of experiments by Leitz interference microscope measurement.
1996,
08.
Abstract:
Large area glow discharge plasma can be used as transparent and high conductive electrodes in electro – optical switches that considerably extended the switch aperture. To investigate problems related to this technology we designed and constructed an 80mm 80mm electro ?optical switch with plasma electrodes. This paper describes the Pockels cell configuration, the discharge electrode geometries, the discharge circuit and parameters. Experimentally, the effect of preionization and gas pressure on discharge performance is observed.
Large area glow discharge plasma can be used as transparent and high conductive electrodes in electro – optical switches that considerably extended the switch aperture. To investigate problems related to this technology we designed and constructed an 80mm 80mm electro ?optical switch with plasma electrodes. This paper describes the Pockels cell configuration, the discharge electrode geometries, the discharge circuit and parameters. Experimentally, the effect of preionization and gas pressure on discharge performance is observed.
1996,
08.
Abstract:
A new achromatic isochronous deflection system is described. It consists of three magnets: two small anti – symmetric dipoles and one dipole with over 90° bending angle. The achromatic and isochronous relations for the system are obtained by six dimension transport matrix method. The system is characterized by excellent achromatic and isochronous properties and compact configuration. The three ?magnet bending system is suitable for linac beam deflection of free ?electron laser facility.
A new achromatic isochronous deflection system is described. It consists of three magnets: two small anti – symmetric dipoles and one dipole with over 90° bending angle. The achromatic and isochronous relations for the system are obtained by six dimension transport matrix method. The system is characterized by excellent achromatic and isochronous properties and compact configuration. The three ?magnet bending system is suitable for linac beam deflection of free ?electron laser facility.
1996,
08.
Abstract:
A ab initio multi – configuration HFR calculation of energy levels and oscillator strengths was carried out in Ni – like sequence from HfXL V to ReXL VIII. Excellent agreement with experiments was obtained. The result was used to analyse our experimental spectra emitted from high power laser – produced plasma.
A ab initio multi – configuration HFR calculation of energy levels and oscillator strengths was carried out in Ni – like sequence from HfXL V to ReXL VIII. Excellent agreement with experiments was obtained. The result was used to analyse our experimental spectra emitted from high power laser – produced plasma.
1996,
08.
Abstract:
Adiabatic acceleration is employed to design the electron gun of HIRFL – CSR e –cooler by using the modified EGUN code. The electron beam transverse temperature variations with anode region and acceleration tube design parameters as well as the uniform solenoidal magnetic field are presented. Transversal temperature of less than 0.1eV at a maximum current density of 0.244A/cm2 are obtained over the full energy range of 2.75 ~ 165keV.
Adiabatic acceleration is employed to design the electron gun of HIRFL – CSR e –cooler by using the modified EGUN code. The electron beam transverse temperature variations with anode region and acceleration tube design parameters as well as the uniform solenoidal magnetic field are presented. Transversal temperature of less than 0.1eV at a maximum current density of 0.244A/cm2 are obtained over the full energy range of 2.75 ~ 165keV.
1996,
08.
Abstract:
The propagation of a radiation heat wave through a thin foil of aluminium has been firstly observed resolved temporally and spectrally in China. The wave is driven by the intense thermal radiation generated in a laser –heated cavity. The mass –ablation rate and shock pressure were obtained from experimental results.
The propagation of a radiation heat wave through a thin foil of aluminium has been firstly observed resolved temporally and spectrally in China. The wave is driven by the intense thermal radiation generated in a laser –heated cavity. The mass –ablation rate and shock pressure were obtained from experimental results.
1996,
08.
Abstract:
In this paper, the capabilities of fitting aberration polynomial of two deformable mirrors which module active thin mirrors are calculated by using finite element method, and the experiments of fitting aberration are introduced. The computation results and the experiment results are coincident very well.
In this paper, the capabilities of fitting aberration polynomial of two deformable mirrors which module active thin mirrors are calculated by using finite element method, and the experiments of fitting aberration are introduced. The computation results and the experiment results are coincident very well.
1996,
08.
Abstract:
The design and computation of a undulator transformed from optical klystron are presented. The brilliance of HLS (NSRL) can be enhanced two orders by the undulator. Lots of experiments which can not be done at the present brilliance will be made possible.
The design and computation of a undulator transformed from optical klystron are presented. The brilliance of HLS (NSRL) can be enhanced two orders by the undulator. Lots of experiments which can not be done at the present brilliance will be made possible.
1996,
08.
Abstract:
The electron 1–D movement for the variable parameter Smith – Purcell FEL is discussed. When the laser operates in state of the low – gain, the analytical expression of the efficiency is derived and a reference formula as how to choose the change rate of the gratting parameter is also given. The numerical simulation results for a radiation output of 1m m ?wavelength are presented. The interaction length between the electrons and the field can be stretched and the efficiency will be enhanced when the change rate is chosed properly.
The electron 1–D movement for the variable parameter Smith – Purcell FEL is discussed. When the laser operates in state of the low – gain, the analytical expression of the efficiency is derived and a reference formula as how to choose the change rate of the gratting parameter is also given. The numerical simulation results for a radiation output of 1m m ?wavelength are presented. The interaction length between the electrons and the field can be stretched and the efficiency will be enhanced when the change rate is chosed properly.
1996,
08.
Abstract:
Closed – form expressions for the relative intensity excess and focal shift of Hermite – Gaussian beams focused by an unaperture lens have been derived and analyzed by means of the generalized Huygens – Fresnel diffraction integral (or called collins formula). For the apertured case we have performed detailed numerical calculations, showing the focusing field characteristics of Hermite – Gaussion beams.
Closed – form expressions for the relative intensity excess and focal shift of Hermite – Gaussian beams focused by an unaperture lens have been derived and analyzed by means of the generalized Huygens – Fresnel diffraction integral (or called collins formula). For the apertured case we have performed detailed numerical calculations, showing the focusing field characteristics of Hermite – Gaussion beams.
1996,
08.
Abstract:
In this paper, the electron beam prebunching in the modulated cavity and shift tube of relativistic klystron amplifier (RKA) is studied analytically, a self – consistent equation of radiation generated by the prebunched electron beam in the radiation cavity is first time derived using the field method of particle – wave interaction instead of the electrical circuit method, and in terms of it, the gain in the linear regime calculated.
In this paper, the electron beam prebunching in the modulated cavity and shift tube of relativistic klystron amplifier (RKA) is studied analytically, a self – consistent equation of radiation generated by the prebunched electron beam in the radiation cavity is first time derived using the field method of particle – wave interaction instead of the electrical circuit method, and in terms of it, the gain in the linear regime calculated.
1996,
08.
Abstract:
In this paper we report Ne-like Zinc X-ray laser experiments in XingGuang facility. Output energy of the facility is 180~200J. We used two pumping way: single pulse and a main pulse with a prepulse. With a single pumping pulse, we observed two laser lines of 26.2nm, 26.7nm (J=2–1). When a prepulse was added, we observed four laser lines of 21.2nm (J=0–1),26.2nm, 26.7nm (J=2–1), 31.4nm (J=2–1).
In this paper we report Ne-like Zinc X-ray laser experiments in XingGuang facility. Output energy of the facility is 180~200J. We used two pumping way: single pulse and a main pulse with a prepulse. With a single pumping pulse, we observed two laser lines of 26.2nm, 26.7nm (J=2–1). When a prepulse was added, we observed four laser lines of 21.2nm (J=0–1),26.2nm, 26.7nm (J=2–1), 31.4nm (J=2–1).
1996,
08.
Abstract:
In this paper the back bombardment of electrons in rf thermionic guns is studied for cavity design. We put forward that shortening the length of cavities can decrease the back bombardment power sharply and obtain electron bunches with better qualities. The simulation results of back bombardment power and electron beam parameters at exit of rf guns with various cavity lengths are presented. The ida has been adopted in the multi – cavity rf thermionic gun for BFEL.
In this paper the back bombardment of electrons in rf thermionic guns is studied for cavity design. We put forward that shortening the length of cavities can decrease the back bombardment power sharply and obtain electron bunches with better qualities. The simulation results of back bombardment power and electron beam parameters at exit of rf guns with various cavity lengths are presented. The ida has been adopted in the multi – cavity rf thermionic gun for BFEL.
1996,
08.
Abstract:
Diagnostic of green laser–produced plasma evolution was conducted on Shenguang laser facility. By utilizing a multipinhole array coupled to a soft X – ray streak camera, the plasma evolution in laser heated area (primary plasmas) and X –ray heated area (secondary plasmas) was observed. Expansion velocities of primary plasmas and secondary were obtained, discussion was also made.
Diagnostic of green laser–produced plasma evolution was conducted on Shenguang laser facility. By utilizing a multipinhole array coupled to a soft X – ray streak camera, the plasma evolution in laser heated area (primary plasmas) and X –ray heated area (secondary plasmas) was observed. Expansion velocities of primary plasmas and secondary were obtained, discussion was also made.
1996,
08.
Abstract:
The hollow cathode pseudospark switch has excellent operating characteristics of high holdoff voltage, high peak current, and rapid current rise. In this paper a computer simulation of its initial discharge coursed is presented. The simulation consists of a 5/2 – dimensional time – dependent fluid model for electron and ion transport using the local field approximation. The result shows that the hollow cathode plays a very important role during the discharge. Also we give the calculation results under different initial triggering charged – particle densities, different gap distances and different cathode hole diameters.
The hollow cathode pseudospark switch has excellent operating characteristics of high holdoff voltage, high peak current, and rapid current rise. In this paper a computer simulation of its initial discharge coursed is presented. The simulation consists of a 5/2 – dimensional time – dependent fluid model for electron and ion transport using the local field approximation. The result shows that the hollow cathode plays a very important role during the discharge. Also we give the calculation results under different initial triggering charged – particle densities, different gap distances and different cathode hole diameters.
1996,
08.
Abstract:
The temporally and spatially resovled measurements of the laser produced plasma in ICF experiment were carried out at the Shenguang laser facility with a multiframe gated microchannel – plate (MCP) X – ray camera. During 1.2ns 12 frame images of the laser produced plasma source were obtained with the camera. The structure of the camera and measure pricinple were described.
The temporally and spatially resovled measurements of the laser produced plasma in ICF experiment were carried out at the Shenguang laser facility with a multiframe gated microchannel – plate (MCP) X – ray camera. During 1.2ns 12 frame images of the laser produced plasma source were obtained with the camera. The structure of the camera and measure pricinple were described.
1996,
08.
Abstract:
In a 100J level XeCl and KrF excimer laser experiment, measurements of e –beam energy deposition in laser gas are reported and satisfactory signals are obtained. As a result, we have obtained several important parameters such as e –beam energy deposition efficiency in laser gas and laser intrinsic efficiency, etc. Also, average pumping rate is calculated, which is helpful for laser adjustment.
In a 100J level XeCl and KrF excimer laser experiment, measurements of e –beam energy deposition in laser gas are reported and satisfactory signals are obtained. As a result, we have obtained several important parameters such as e –beam energy deposition efficiency in laser gas and laser intrinsic efficiency, etc. Also, average pumping rate is calculated, which is helpful for laser adjustment.
1996,
08.
Abstract:
A failure experiment of internally pressured cylinder shell under laser irradiation is presented in Ref. [1]. To research the failure phenomenon, a thermo –elastoplastic numerical model is established in this paper. In this model, a heat conduction analysis coupled with strain rate is applied and factors such as the physical properties of material changing with the temperature and the pre-loading of the internal pressure are considered. The sub-structure method applied in this paper successfully confines the coupled heat conduction analysis and thermo –elastoplastic analysis in a much smaller range. The numerical results tally with those of Ref. [1]. It shows that the numerical model can describe the whole process of the thermal softening failure fairly well.
A failure experiment of internally pressured cylinder shell under laser irradiation is presented in Ref. [1]. To research the failure phenomenon, a thermo –elastoplastic numerical model is established in this paper. In this model, a heat conduction analysis coupled with strain rate is applied and factors such as the physical properties of material changing with the temperature and the pre-loading of the internal pressure are considered. The sub-structure method applied in this paper successfully confines the coupled heat conduction analysis and thermo –elastoplastic analysis in a much smaller range. The numerical results tally with those of Ref. [1]. It shows that the numerical model can describe the whole process of the thermal softening failure fairly well.
1996,
08.
Abstract:
Synchronizing hyperchaos is realized by the drive –response relationship in the complex Lorenz –Haken system and its higher –order cascading systems. Controlling hyperchaos is achieved by the intermittent proportional feedback to all of the drive system variable. The idea and concepts may be extended to some nonlinear dynamical systems. The prospects for potential applications is indicated.
Synchronizing hyperchaos is realized by the drive –response relationship in the complex Lorenz –Haken system and its higher –order cascading systems. Controlling hyperchaos is achieved by the intermittent proportional feedback to all of the drive system variable. The idea and concepts may be extended to some nonlinear dynamical systems. The prospects for potential applications is indicated.
1996,
08.
Abstract:
Annular intense beam for relativistic klystron can offer much higher DC power. Even the efficiency is decreased, a higher radiation can be expected. At the same time, annular intense beam can provide electrostatic insulation, thereby preventing the RF breakdown across a gap that is normally expected in the generation of high power RF. More than 5MW radiation is observed.
Annular intense beam for relativistic klystron can offer much higher DC power. Even the efficiency is decreased, a higher radiation can be expected. At the same time, annular intense beam can provide electrostatic insulation, thereby preventing the RF breakdown across a gap that is normally expected in the generation of high power RF. More than 5MW radiation is observed.
1996,
08.
Abstract:
In this paper, the 3 – dimensional ASE calculation for electron beam pumping XeCl excimer laser is presented by M – C method. In this model wall – reflected ASE is included. This calculation also includes nonsaturable absorption and mirror that reflect ASE flux back into the active gain medium. Results are presented that show optimum scaling of injected flux. It can provide theoretical basis and experimental references for experiments on excimer lasers, and be extrapolated to any other type of laser.
In this paper, the 3 – dimensional ASE calculation for electron beam pumping XeCl excimer laser is presented by M – C method. In this model wall – reflected ASE is included. This calculation also includes nonsaturable absorption and mirror that reflect ASE flux back into the active gain medium. Results are presented that show optimum scaling of injected flux. It can provide theoretical basis and experimental references for experiments on excimer lasers, and be extrapolated to any other type of laser.
1996,
08.
Abstract:
A pulse generator used for driving an electro –optical switch based on plasma electrodes is constructed. The output pulse is formed by cables, and controlled by a field distrotion switch. In this paper, the effect of the circuit parameters of the field distortion switch on the output pulses and approaches to improve the pulse waveforms are discribed. Finally, the experimental results are given.
A pulse generator used for driving an electro –optical switch based on plasma electrodes is constructed. The output pulse is formed by cables, and controlled by a field distrotion switch. In this paper, the effect of the circuit parameters of the field distortion switch on the output pulses and approaches to improve the pulse waveforms are discribed. Finally, the experimental results are given.
1996,
08.
Abstract:
We present a modes expansion method that is used to calculate spontaneous emission radiated by the radio – frequency (RF) modulated short pulse electron beam, which the radiation is confined in the rectangular waveguide. The modes expansion coefficients determine the radiation power into the TE0n modes. Taking the short pulse as an ideal delta function on time scale, we find that the radiation field pattern is just of the 損ure?waveguide modes if the resonance frequency equals as integral times as radio frequency. Finally, evaluating the power of Shanghai RF far infrared waveguide free electron laser which is being designed is performed.
We present a modes expansion method that is used to calculate spontaneous emission radiated by the radio – frequency (RF) modulated short pulse electron beam, which the radiation is confined in the rectangular waveguide. The modes expansion coefficients determine the radiation power into the TE0n modes. Taking the short pulse as an ideal delta function on time scale, we find that the radiation field pattern is just of the 損ure?waveguide modes if the resonance frequency equals as integral times as radio frequency. Finally, evaluating the power of Shanghai RF far infrared waveguide free electron laser which is being designed is performed.
1996,
08.
Abstract:
A plasma kinetic analysis and a nonlinear particle simulation on a hybrid peniotron are made in this paper. The kinetic results point out it is a hybrid device which is based on peniotron抯 operating mechanism. The simulation verifies this conclusion and shows it has two merits: high efficiency and high frequency.
A plasma kinetic analysis and a nonlinear particle simulation on a hybrid peniotron are made in this paper. The kinetic results point out it is a hybrid device which is based on peniotron抯 operating mechanism. The simulation verifies this conclusion and shows it has two merits: high efficiency and high frequency.
