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RSS1993 Vol. 05, No. 03
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1993,
05: 325-332.
Abstract:
The operational principles, dynamic measurement and experimental results of a picosecond X-ray framing camera are described in this paper. The experiments have shown that this camera can provide 3 frame images with exposure time 75ps (FWHM), interframe time 150ps. Dynamic spatial resolution is better than 61p/mm, trigger jitter time for 80% shots<±30ps, and geometric distortion < ±5%.
The operational principles, dynamic measurement and experimental results of a picosecond X-ray framing camera are described in this paper. The experiments have shown that this camera can provide 3 frame images with exposure time 75ps (FWHM), interframe time 150ps. Dynamic spatial resolution is better than 61p/mm, trigger jitter time for 80% shots<±30ps, and geometric distortion < ±5%.
1993,
05: 333-343.
Abstract:
r This article presents results of nuclear fusion at normal temperature of Southwest Institute of Nuclear Physics and Chemistry in collaboration with Beijing Institute of Applied physics and Computational Mathematics. Neutrons and tritium are observed using electrolysis. Neutrons and X rays are observed using gas-discharge. Exposure phenomen a of X-ray film were found in the cycle method of temperature and pressure (CMTP). The reason of exposure were preliminarily analyzed.
r This article presents results of nuclear fusion at normal temperature of Southwest Institute of Nuclear Physics and Chemistry in collaboration with Beijing Institute of Applied physics and Computational Mathematics. Neutrons and tritium are observed using electrolysis. Neutrons and X rays are observed using gas-discharge. Exposure phenomen a of X-ray film were found in the cycle method of temperature and pressure (CMTP). The reason of exposure were preliminarily analyzed.
1993,
05: 344-352.
Abstract:
A 15-cm DuoPIGatron ion source has been developed as a neutral beam source. This source has achieved extracted beam currents of 20A at 30kV and 20ms, target power of 463kW and beam divergence of 1.6°. In this paper, the structure, experimental system, experimental results and the performance of the developed source are presented.
A 15-cm DuoPIGatron ion source has been developed as a neutral beam source. This source has achieved extracted beam currents of 20A at 30kV and 20ms, target power of 463kW and beam divergence of 1.6°. In this paper, the structure, experimental system, experimental results and the performance of the developed source are presented.
1993,
05: 353-358.
Abstract:
This paper describes the principle of the energy spectrum measurement system including the magnetic analyzer and image processing unit. The experimental results of the 3.3MeV LIA IPEB are presented. The most possible energy is 3.47MeV, and the maximum 3.51MeV. The energy spread is 1%. The energy spectrum distribution of the IPEB is given. Discussion on the experimental results and the measurement of IPEB energy spectrum are made in the paper. The main effect factors on the energy and its spread of the LIA IPEB are also analyzed and calculated numerically.
This paper describes the principle of the energy spectrum measurement system including the magnetic analyzer and image processing unit. The experimental results of the 3.3MeV LIA IPEB are presented. The most possible energy is 3.47MeV, and the maximum 3.51MeV. The energy spread is 1%. The energy spectrum distribution of the IPEB is given. Discussion on the experimental results and the measurement of IPEB energy spectrum are made in the paper. The main effect factors on the energy and its spread of the LIA IPEB are also analyzed and calculated numerically.
1993,
05: 359-366.
Abstract:
Approximate scaling laws for the saturation intensity and the saturation length in a millimeter wave free electron laser amplifier with untapered wiggler are derived by uniting numerical simulations with scaling analyses.
Approximate scaling laws for the saturation intensity and the saturation length in a millimeter wave free electron laser amplifier with untapered wiggler are derived by uniting numerical simulations with scaling analyses.
1993,
05: 367-373.
Abstract:
A new method of compensating for resistive voltage dividers is proposed in this paper. This method is characterized by high resistance in the high voltage arm of a one-stage divider, and the compensation for risetime is fulfilled by the inductance of the low arm itself. A divider has been designed with this method to measure megavolt, nanosecond signals. A risetime of about Ins has been achieved with this divider.
A new method of compensating for resistive voltage dividers is proposed in this paper. This method is characterized by high resistance in the high voltage arm of a one-stage divider, and the compensation for risetime is fulfilled by the inductance of the low arm itself. A divider has been designed with this method to measure megavolt, nanosecond signals. A risetime of about Ins has been achieved with this divider.
1993,
05: 374-378.
Abstract:
A simple Monte Carlo method is presented to calculate the energy spectrum of an electron beam transmitting through foils. And we use this method to calculate the electron beam's spectrum after transmission through anode foil of diode, HIBACHI and main foil, which is used as a pumping source of laser.
A simple Monte Carlo method is presented to calculate the energy spectrum of an electron beam transmitting through foils. And we use this method to calculate the electron beam's spectrum after transmission through anode foil of diode, HIBACHI and main foil, which is used as a pumping source of laser.
1993,
05: 379-384.
Abstract:
The performance of XeCl excimer laser-triggered DC-charged gas (N2, SF6) switches was studied. The experimental results indicated that triggering thresholds of XeCl laser (λ = 308nm, FWHM=21ns) for N2 and SF6 were about 108W/cm2 at 0.1 MPa and 80% VSB and the delay and jitter time decreased with increasing of laser energy and undervoltage ratio. At 90% Fsg (VSB = 36.5kV) and 33.8mJ of laser energy, the delay and jitter time of nitrogen switch was less than 85.5ns and 400ps, respectively. At the same undervoltage ratio, the minimum jitter for SF6 switch (VSB=52kV) was 2ns. The delay of SF6 gas switch was consistent with that given by T. H.Martin's formula.
The performance of XeCl excimer laser-triggered DC-charged gas (N2, SF6) switches was studied. The experimental results indicated that triggering thresholds of XeCl laser (λ = 308nm, FWHM=21ns) for N2 and SF6 were about 108W/cm2 at 0.1 MPa and 80% VSB and the delay and jitter time decreased with increasing of laser energy and undervoltage ratio. At 90% Fsg (VSB = 36.5kV) and 33.8mJ of laser energy, the delay and jitter time of nitrogen switch was less than 85.5ns and 400ps, respectively. At the same undervoltage ratio, the minimum jitter for SF6 switch (VSB=52kV) was 2ns. The delay of SF6 gas switch was consistent with that given by T. H.Martin's formula.
1993,
05: 385-388.
Abstract:
In this paper, the LIF spectrum of CuCl2 was obtained and analyzed. By comparing the LIF spectrum of CuCl2 with the spectrum of the red emission from the cavity of COIL and recorded by Fourier transform spectrometer, we confirm that the red emitter is doubtless CuCl2.
In this paper, the LIF spectrum of CuCl2 was obtained and analyzed. By comparing the LIF spectrum of CuCl2 with the spectrum of the red emission from the cavity of COIL and recorded by Fourier transform spectrometer, we confirm that the red emitter is doubtless CuCl2.
1993,
05: 389-393.
Abstract:
A high power CW chemical oxygen-iodine laser was studied. The output power of IkW was achieved at a Cl2 flow rate of 50mmol/s. The beam divergence was measured. The relation of the beam divergence vs. the output power and the curvature radius of the total reflector was investigated.
A high power CW chemical oxygen-iodine laser was studied. The output power of IkW was achieved at a Cl2 flow rate of 50mmol/s. The beam divergence was measured. The relation of the beam divergence vs. the output power and the curvature radius of the total reflector was investigated.
1993,
05: 394-404.
Abstract:
Whole-beam thermal blooming experiments have been done using a focused long pulse laser (τP= 1.8ms, E = 2001, angle spread θ = 2mrad). A blooming cell is full of ammonia at 0 -6 atmosphere pressure. A CCD system is used to measure the diameter of the distorted laser beam waist and the intensity profile of the spot at waist. The absorption cofficients are measured by a digital calorimeter. The instantaneous irradiation intensity at spot centre is measured by a photodiode digital collector-Roland mapper-Computer system. The instantaneous intensity profile is measured by a high speed camera.
Whole-beam thermal blooming experiments have been done using a focused long pulse laser (τP= 1.8ms, E = 2001, angle spread θ = 2mrad). A blooming cell is full of ammonia at 0 -6 atmosphere pressure. A CCD system is used to measure the diameter of the distorted laser beam waist and the intensity profile of the spot at waist. The absorption cofficients are measured by a digital calorimeter. The instantaneous irradiation intensity at spot centre is measured by a photodiode digital collector-Roland mapper-Computer system. The instantaneous intensity profile is measured by a high speed camera.
1993,
05: 405-414.
Abstract:
In order to receive the information of intense X-ray source inside cavity target with a size of a few hundreds micrometers, an aperture with ressonable scale is often designed in the wall of the cavity. X rays from inside rapidly heat the material of pinholerin, producing an ablation cloud that impedes transmission of the radiation signal viewed from the outside. So the transmission of intense radiation signal through pinhole is affected by the material and size of the pinhole, and depends on the parameters, for example, equivalent blackbody temperature and pulse shape etc. An analytical model which provides insight into the physics of closure process, is developed to describe the plasma closure effect.
In order to receive the information of intense X-ray source inside cavity target with a size of a few hundreds micrometers, an aperture with ressonable scale is often designed in the wall of the cavity. X rays from inside rapidly heat the material of pinholerin, producing an ablation cloud that impedes transmission of the radiation signal viewed from the outside. So the transmission of intense radiation signal through pinhole is affected by the material and size of the pinhole, and depends on the parameters, for example, equivalent blackbody temperature and pulse shape etc. An analytical model which provides insight into the physics of closure process, is developed to describe the plasma closure effect.
1993,
05: 415-424.
Abstract:
Experiments of planar and cylindrical hohlraum targets have been conducted on " Shenguang" laser Facility in recent years. A multichannel filter-flourescer spectrometer was used to obtain the hard X -ray spectrum. The temperature and energy of suprathermal electrons were induced from the hard X-ray spectrum. When the energy of a single beam of incident laser is in the range of 400 - 670J, and the pulse duration in the range of 650 -1150ps, it is found that two groups of suprathermal electrons obey Maxwellian distribution (Th = 35 - 45keV, Thh= 150 - 350keV) in hohlraums, and total energy of suprathermal electrons Ehe is about 10%-12% of incident laser energy. Experiments also show that Ehe is fairly concordant with the amount of stimulated Raman scattered (SRS) light, so we can conclude that SRS is the primary mechanism for producing suprathermal electrons in hohlraum targets. Fraction of suprathermal electrons in hohlraum is bigger than that of planar. The results are analysed and discussed.
Experiments of planar and cylindrical hohlraum targets have been conducted on " Shenguang" laser Facility in recent years. A multichannel filter-flourescer spectrometer was used to obtain the hard X -ray spectrum. The temperature and energy of suprathermal electrons were induced from the hard X-ray spectrum. When the energy of a single beam of incident laser is in the range of 400 - 670J, and the pulse duration in the range of 650 -1150ps, it is found that two groups of suprathermal electrons obey Maxwellian distribution (Th = 35 - 45keV, Thh= 150 - 350keV) in hohlraums, and total energy of suprathermal electrons Ehe is about 10%-12% of incident laser energy. Experiments also show that Ehe is fairly concordant with the amount of stimulated Raman scattered (SRS) light, so we can conclude that SRS is the primary mechanism for producing suprathermal electrons in hohlraum targets. Fraction of suprathermal electrons in hohlraum is bigger than that of planar. The results are analysed and discussed.
1993,
05: 425-432.
Abstract:
Electron emission produced by fast polarization change of the ferroelectrics is a potential electron beam source. Both experimental modse, E ∥ P and E ⊥ P , as well as their behaviors are reported in this paper. J - E characteristics of both materials, PZT - 95/5 and PLZT -1/95/5, for different modes are given. It's pointed out that the presence of the metal strip grid is a disfavour factor, which results in redistribution of the current between the anode and the strip grid electrode. Moreover, the limited breakdown threshold of the sample is a main hinder for increasing excitation field. In order to overcome these difficults, a mode, E ⊥ P , has been developed using "polarization rotation" idea to replace "polarization reversion" . This idea has been confirmed by our experiments.
Electron emission produced by fast polarization change of the ferroelectrics is a potential electron beam source. Both experimental modse, E ∥ P and E ⊥ P , as well as their behaviors are reported in this paper. J - E characteristics of both materials, PZT - 95/5 and PLZT -1/95/5, for different modes are given. It's pointed out that the presence of the metal strip grid is a disfavour factor, which results in redistribution of the current between the anode and the strip grid electrode. Moreover, the limited breakdown threshold of the sample is a main hinder for increasing excitation field. In order to overcome these difficults, a mode, E ⊥ P , has been developed using "polarization rotation" idea to replace "polarization reversion" . This idea has been confirmed by our experiments.
1993,
05: 433-439.
Abstract:
A numerical study has been made of the start up for the far infrared RF-FEL oscillator in which the electron pulse length is comparable to the slippage between the electrons and the light occurring inside the Wiggler in this paper. We show that the laser lethargy can be overcome and the oscillator can start up if there is a adequate detuning in the optical cavity length. The laser power and efficiency can grow more if we use the optimum methode to detune the optical resonator.
A numerical study has been made of the start up for the far infrared RF-FEL oscillator in which the electron pulse length is comparable to the slippage between the electrons and the light occurring inside the Wiggler in this paper. We show that the laser lethargy can be overcome and the oscillator can start up if there is a adequate detuning in the optical cavity length. The laser power and efficiency can grow more if we use the optimum methode to detune the optical resonator.
1993,
05: 440-444.
Abstract:
Energy levels, wavelengths, oscillator strengths, Auger rates and level-to-level dielectronic recombination rate coefficients describing dielectronic recombination into excited levels of Li-like yttrium ions from He -like ground state are calculated. Our calculations are based on Dr. R. D. Cowan's semi -relativistic multi-configuration Hartree-Fock (HFR) code, where the relativistic mass -velocity and Darwin corrections are included in the Hamiltonian, and the distorted-wave model is used for the calculation of free electron wavefunctions. The dielectronic recombination rate coefficients as a function of free electron temperatures are given in an analytical form which is not only very convenient in practice but also accurate enough compared with the exactly calculated numerical results.
Energy levels, wavelengths, oscillator strengths, Auger rates and level-to-level dielectronic recombination rate coefficients describing dielectronic recombination into excited levels of Li-like yttrium ions from He -like ground state are calculated. Our calculations are based on Dr. R. D. Cowan's semi -relativistic multi-configuration Hartree-Fock (HFR) code, where the relativistic mass -velocity and Darwin corrections are included in the Hamiltonian, and the distorted-wave model is used for the calculation of free electron wavefunctions. The dielectronic recombination rate coefficients as a function of free electron temperatures are given in an analytical form which is not only very convenient in practice but also accurate enough compared with the exactly calculated numerical results.
1993,
05: 445-448.
Abstract:
Based on the statistic independent property of the effects of rough surface and atmospheric turbulence on a propagation laser beam, a formulation for the probability density function of the unwrapped phase of a elliptic Gaussian speckle field that propagates through clear air turbulence is developed.
Based on the statistic independent property of the effects of rough surface and atmospheric turbulence on a propagation laser beam, a formulation for the probability density function of the unwrapped phase of a elliptic Gaussian speckle field that propagates through clear air turbulence is developed.
1993,
05: 449-453.
Abstract:
Based on minimum spot condition, a method for laser beam quality measurement is proposed. From beam diameter measurements at two locations along laser beam propagation axis, location of beam waist, waist width, far-field divergence angle and M2 factor can be given.
Based on minimum spot condition, a method for laser beam quality measurement is proposed. From beam diameter measurements at two locations along laser beam propagation axis, location of beam waist, waist width, far-field divergence angle and M2 factor can be given.
1993,
05: 454-458.
Abstract:
This report describes the experimental calibration principle of the fast response GaAs detector, using bremsstrahlung radiation pulse of the Flash-I setup and presents experimental results and analytical discussion.
This report describes the experimental calibration principle of the fast response GaAs detector, using bremsstrahlung radiation pulse of the Flash-I setup and presents experimental results and analytical discussion.
1993,
05: 459-463.
Abstract:
In order to measure X -ray conversion and transport efficiencies of hohlraum targets, we have conducted experiments on leaking targets on "SHENGUANG" facility for four times from 1989 to 1992 using flat response X-ray diods. We have obtained the X-ray anguler distribution, conversion efficiency and transport efficiency of hohlraum targets. The data are very important to theoretical calculation and design of targets.
In order to measure X -ray conversion and transport efficiencies of hohlraum targets, we have conducted experiments on leaking targets on "SHENGUANG" facility for four times from 1989 to 1992 using flat response X-ray diods. We have obtained the X-ray anguler distribution, conversion efficiency and transport efficiency of hohlraum targets. The data are very important to theoretical calculation and design of targets.
1993,
05: 464-468.
Abstract:
XUV spectra from GeXX Ⅱ in laser-produced plasmas are identified. The intensities of the transtions from 3p2P3/2-3d2D5/2 and 3s2S1/2 -3p2P3/2 are sensitive to electron densities between 1019 and 1021/cm3 and not sensitive to the electron temperature. Calculations of the intensity ratio vs the electron density are performed. Electron densities in laser-produced Ge plasmas have been deduced from the ratio.
XUV spectra from GeXX Ⅱ in laser-produced plasmas are identified. The intensities of the transtions from 3p2P3/2-3d2D5/2 and 3s2S1/2 -3p2P3/2 are sensitive to electron densities between 1019 and 1021/cm3 and not sensitive to the electron temperature. Calculations of the intensity ratio vs the electron density are performed. Electron densities in laser-produced Ge plasmas have been deduced from the ratio.
1993,
05: 469-471.
Abstract:
The principle of hole array wavefront sensor is described and the phase distribution of a 3.8 μm DF high power laser beam has been obtained using this method.
The principle of hole array wavefront sensor is described and the phase distribution of a 3.8 μm DF high power laser beam has been obtained using this method.
1993,
05: 472-480.
Abstract:
The recently appeared several nevel optical unstable resonators are reviewed. Their characteristics and development are analysed.
The recently appeared several nevel optical unstable resonators are reviewed. Their characteristics and development are analysed.
