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RSS1993 Vol. 05, No. 02
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1993,
05: 165-172.
Abstract:
In the experiment of X-ray laser with four-target series coupling, a time-resolved crystal spectrograph was used to record the resonant spectral lines of Ne- like Ge ions and their satellites. Emission time of these lines was measured to be about 0.95ns (FWHM). The time evolution of electron temperature Te of Ge plasma obtained showed that the duration of Te (≥400eV) was larger than 1.2ns.A space-resolved crystal spectrograph.was used to diagnose the distribution of electron temperature Te and density ne along the axis of the Ge plasma column. The average values of Te and ne were 4.9 × 102eV and 1.2 × 1020cm-3 respectively.
In the experiment of X-ray laser with four-target series coupling, a time-resolved crystal spectrograph was used to record the resonant spectral lines of Ne- like Ge ions and their satellites. Emission time of these lines was measured to be about 0.95ns (FWHM). The time evolution of electron temperature Te of Ge plasma obtained showed that the duration of Te (≥400eV) was larger than 1.2ns.A space-resolved crystal spectrograph.was used to diagnose the distribution of electron temperature Te and density ne along the axis of the Ge plasma column. The average values of Te and ne were 4.9 × 102eV and 1.2 × 1020cm-3 respectively.
1993,
05: 173-180.
Abstract:
In order to explore new pumping mechanism of x -ray lasers, we have studied the x rays radiated by the pump target. The experiments were successively performed at "Xing guang" and " Shen guang" facilities. The results obtained at " Shen guang" are emphatically introduced in this paper. The targets used are made of Na/F or Cu. The x -ray spectra from Na/ F or Cu (wavelength is respectively within 1.1- l.5nm and 1.1- 1.3nm) are given. The curves of the x -ray relative intensity versus laser intensity and thickness of the target are showed. The x-ray relative intensity in front of the target is compared with that in back of the target. Meanwhile, the spatial distribution of the x rays from the line pumping source is obtained in the experiment.
In order to explore new pumping mechanism of x -ray lasers, we have studied the x rays radiated by the pump target. The experiments were successively performed at "Xing guang" and " Shen guang" facilities. The results obtained at " Shen guang" are emphatically introduced in this paper. The targets used are made of Na/F or Cu. The x -ray spectra from Na/ F or Cu (wavelength is respectively within 1.1- l.5nm and 1.1- 1.3nm) are given. The curves of the x -ray relative intensity versus laser intensity and thickness of the target are showed. The x-ray relative intensity in front of the target is compared with that in back of the target. Meanwhile, the spatial distribution of the x rays from the line pumping source is obtained in the experiment.
1993,
05: 181-190.
Abstract:
In this paper, plasma transport equations are derived under the condition that the collision term in the equation is taken as Boltzmann form and the distribution function is approximately Maxwellian.Neglecting the time derivative term, we get the formula of transport coefficients. Then we have compared our results with those in refferences [1] and [2]. It is shown that the dependence of transport coefficients on plasma parameters is almost the same, but the specific values of some coefficients are different from those in references [1] and [2].
In this paper, plasma transport equations are derived under the condition that the collision term in the equation is taken as Boltzmann form and the distribution function is approximately Maxwellian.Neglecting the time derivative term, we get the formula of transport coefficients. Then we have compared our results with those in refferences [1] and [2]. It is shown that the dependence of transport coefficients on plasma parameters is almost the same, but the specific values of some coefficients are different from those in references [1] and [2].
1993,
05: 191-197.
Abstract:
This paper continues the discussion of reference [1], analysing the influence of the transverse component of the electromagnetic field in the gap of a linear induction accelerator on the emittance growth of the electron beam with a different approach of beam optics. The same result is obtained. Some conclusions are given.
This paper continues the discussion of reference [1], analysing the influence of the transverse component of the electromagnetic field in the gap of a linear induction accelerator on the emittance growth of the electron beam with a different approach of beam optics. The same result is obtained. Some conclusions are given.
1993,
05: 198-202.
Abstract:
In this paper, the interaction of intense pulsed electron beams with dielectric targets is presented. The cracks in the crystal and the dendrites of discharge in polymer are analyzed and discussed with fractal geometry. It has been proved that the deposition of beam energy and electrons leads to those phenomena.
In this paper, the interaction of intense pulsed electron beams with dielectric targets is presented. The cracks in the crystal and the dendrites of discharge in polymer are analyzed and discussed with fractal geometry. It has been proved that the deposition of beam energy and electrons leads to those phenomena.
1993,
05: 203-216.
Abstract:
A code of 3D-FEL amplifier with single mode was established on a 386-microcomputer which only takes 20minutes for single pass. Using this code, we found : 1.emittance causes exponential changes of output power, 2.the geometry of electron phase space has important influence on output power in two aspects which leads to (a) different equivalent.energy spread and (b) different match condition between electron beam and optical beam, and 3.nonideal incidence of e-beam beyond some region causes the exponential reduction of output power.
A code of 3D-FEL amplifier with single mode was established on a 386-microcomputer which only takes 20minutes for single pass. Using this code, we found : 1.emittance causes exponential changes of output power, 2.the geometry of electron phase space has important influence on output power in two aspects which leads to (a) different equivalent.energy spread and (b) different match condition between electron beam and optical beam, and 3.nonideal incidence of e-beam beyond some region causes the exponential reduction of output power.
1993,
05: 217-220.
Abstract:
We have studied the gain characteristic of a FEL and found that there is a kind of micro -FEL device with super-high gains. This FEL device lies in the far infrared range, It consists of a rflinac with a high brightness electron beam, a microwiggler, and a capillary waveguide. micro-FEL device, super-high gain, microwiggler, capillary waveguide.
We have studied the gain characteristic of a FEL and found that there is a kind of micro -FEL device with super-high gains. This FEL device lies in the far infrared range, It consists of a rflinac with a high brightness electron beam, a microwiggler, and a capillary waveguide. micro-FEL device, super-high gain, microwiggler, capillary waveguide.
1993,
05: 221-227.
Abstract:
In this paper, the thermal shock wave and damage effect of LY 12 aluminum alloy exposed to an electron beam are theoretically calculated. The calculated results are consistent with the experimental results. The melting process should be adequately taken into account for the studies of the material dynamic response in the intermediate energy deposition range. The equation of state (EOS) model used is a GRAY three phase EOS. When the damage effect of materr als is studied, the Bodner - Partom constitutive equation for the elastic -viscoplastic damage materials is modified.
In this paper, the thermal shock wave and damage effect of LY 12 aluminum alloy exposed to an electron beam are theoretically calculated. The calculated results are consistent with the experimental results. The melting process should be adequately taken into account for the studies of the material dynamic response in the intermediate energy deposition range. The equation of state (EOS) model used is a GRAY three phase EOS. When the damage effect of materr als is studied, the Bodner - Partom constitutive equation for the elastic -viscoplastic damage materials is modified.
1993,
05: 228-232.
Abstract:
With the development of free electron lasers (FELs), high brightness microwave electron gun is being paid more and more attention. An thermionic cathode microwave electron gun with monocrystal LaB6 was designed and tested in the Institute of High Energy Physics, in order to meet the requirement of Beijing Free Electron Laser (BFEL).This paper presents the methods of solving the problems encountered in the research such as surface treatment, holding and heating of LaB6. The electron beam melting was used to melt LaB6 with base metal tantalum at first. The emission current density is 84A/cm2, the life time of the cathode is 200 hours and the lifetime of the heater is longer than 500 hours.
With the development of free electron lasers (FELs), high brightness microwave electron gun is being paid more and more attention. An thermionic cathode microwave electron gun with monocrystal LaB6 was designed and tested in the Institute of High Energy Physics, in order to meet the requirement of Beijing Free Electron Laser (BFEL).This paper presents the methods of solving the problems encountered in the research such as surface treatment, holding and heating of LaB6. The electron beam melting was used to melt LaB6 with base metal tantalum at first. The emission current density is 84A/cm2, the life time of the cathode is 200 hours and the lifetime of the heater is longer than 500 hours.
1993,
05: 233-238.
Abstract:
On the basis of a relativistic self-consistent temperature and density-dependent Hartree-Slater "average atom" model, the error of electron conductive opacities by approximating the self-consistent electron-ion potential with two superimposed Yukawa potentials was checked. The electron conductive opacities for titanium are given by the direct numerical integral at temperatures ranging from 10eV to 103eV and for densities from 0.1 p0 to 10/7n(p0 = 3.988g/cm3).
On the basis of a relativistic self-consistent temperature and density-dependent Hartree-Slater "average atom" model, the error of electron conductive opacities by approximating the self-consistent electron-ion potential with two superimposed Yukawa potentials was checked. The electron conductive opacities for titanium are given by the direct numerical integral at temperatures ranging from 10eV to 103eV and for densities from 0.1 p0 to 10/7n(p0 = 3.988g/cm3).
1993,
05: 239-242.
Abstract:
The paper introduces a new type of pulse detector and the modification by neutron radiation, and reports the experimental results of the relation between the detector character and neutron fluence. A detector of a time response less than 200ps has been obtained in our experiment.
The paper introduces a new type of pulse detector and the modification by neutron radiation, and reports the experimental results of the relation between the detector character and neutron fluence. A detector of a time response less than 200ps has been obtained in our experiment.
1993,
05: 243-252.
Abstract:
Thermal blooming in atmospheric laser propagation is studied using Fast Fourier Transformation. Variations of steady state thermal blooming with laser power and propagation distance are introduced and power threshold is also calculated. Time-dependent thermal blooming effects with and without wind are also considered.
Thermal blooming in atmospheric laser propagation is studied using Fast Fourier Transformation. Variations of steady state thermal blooming with laser power and propagation distance are introduced and power threshold is also calculated. Time-dependent thermal blooming effects with and without wind are also considered.
1993,
05: 253-262.
Abstract:
In this paper, we present the numerical results of thermal blooming calculation with the 4 -D code. We have carried out the numerical simulation of phase compensation and field compensation used the 4 -D code which includes the beacon. The calculation results shows that phase only compensation is instable (PC I), but field compensation is completely effective.
In this paper, we present the numerical results of thermal blooming calculation with the 4 -D code. We have carried out the numerical simulation of phase compensation and field compensation used the 4 -D code which includes the beacon. The calculation results shows that phase only compensation is instable (PC I), but field compensation is completely effective.
1993,
05: 263-270.
Abstract:
From the idea of stimulated light scattering, the coupling-waves equations of two-modes scattering for Laser propagation in the atmosphere is derived in this paper. On the condition of frequence shift of scattered light (acoustic wave frequence) equals zero (ω=0). these equations reduce to the corresponding equations in Karr's literature [1]. The fundamental pictures for small-scale instabilities induced by STRS of HEL propagation in the atmosphere are obtained using numerical simulation 4D program. The results are similar to that of transversal spacing being infinit in [1].
From the idea of stimulated light scattering, the coupling-waves equations of two-modes scattering for Laser propagation in the atmosphere is derived in this paper. On the condition of frequence shift of scattered light (acoustic wave frequence) equals zero (ω=0). these equations reduce to the corresponding equations in Karr's literature [1]. The fundamental pictures for small-scale instabilities induced by STRS of HEL propagation in the atmosphere are obtained using numerical simulation 4D program. The results are similar to that of transversal spacing being infinit in [1].
1993,
05: 271-276.
Abstract:
The relationship between the magnification and cavity length to the set up time of the laser mode with diffraction limited divergence in high gain KrF laser is given, and its effect on the output beam is studied. The divergence of output beam from positive branch confocal unstable resonator with M = 8, L = 1.75m and with M = 13.3, L = 1.85m is measured. Under the 30kV charge voltage, the divergences of resonator M=8 and M=13.3 are 39 and 33 times diffraction -limited divergence respectively, and as charge voltage is 26kV, they are 20 and 5 times individualy. The results of the experiment indicated that the set up time of the diffraction limited mode in the resonator is influenced by magnification, cavity length and the gain saturation effect of the laser. It is necessary that the set-up time of the diffraction limited mode must be less than the saturation time of the light in the cavity in order to get a diffraction -limited mode.
The relationship between the magnification and cavity length to the set up time of the laser mode with diffraction limited divergence in high gain KrF laser is given, and its effect on the output beam is studied. The divergence of output beam from positive branch confocal unstable resonator with M = 8, L = 1.75m and with M = 13.3, L = 1.85m is measured. Under the 30kV charge voltage, the divergences of resonator M=8 and M=13.3 are 39 and 33 times diffraction -limited divergence respectively, and as charge voltage is 26kV, they are 20 and 5 times individualy. The results of the experiment indicated that the set up time of the diffraction limited mode in the resonator is influenced by magnification, cavity length and the gain saturation effect of the laser. It is necessary that the set-up time of the diffraction limited mode must be less than the saturation time of the light in the cavity in order to get a diffraction -limited mode.
1993,
05: 277-282.
Abstract:
The on-line spatial image analysis system for laser-produced plasmas consists of an imaging element with double slits or a pinhole, MCP image intensifier, a CCD camera and a pattern processing device. The spectral range is from 1 to 100nm with electron gain of 104, spatial resolution (two-dimensional)of about 15 1p/mm, and dynamic range of 104. In 1991, this system was successfully used in ICF experiments. This paper describes the functions and the characteristics of the system and gives some experimental results.
The on-line spatial image analysis system for laser-produced plasmas consists of an imaging element with double slits or a pinhole, MCP image intensifier, a CCD camera and a pattern processing device. The spectral range is from 1 to 100nm with electron gain of 104, spatial resolution (two-dimensional)of about 15 1p/mm, and dynamic range of 104. In 1991, this system was successfully used in ICF experiments. This paper describes the functions and the characteristics of the system and gives some experimental results.
1993,
05: 283-289.
Abstract:
In free electron laser with a long, linear wiggler, the magnetic field at the entrance of wiggler and the external focusing required to deep the electron beam from dispersing can determine the character of the electron orbits and seriously influence the PEL gain. To obtain good results in PEL experiments, it is necessary to investigate the linearly polarized wiggler with good magnetic field at the entrance and self-focusing.
In this paper, it is researched in details that the entrance magnetic field and self-focusing of the linearly polarized wiggler produced by doubje bifilar helix lines. (1) The integral formula of the magnetic field on Z axis of the wiggler is derived, the prediction by the formula is good with the experiment, the results show that the field symmetry is better than the bifilar helix wiggler's. (2) According to Lorentz equation, we have derived the electron trajactory equations with the stable motions, and the formula about the threshold transport e-beam current and the wiggler peak field, simulated the orbits of the electron at edge in the wiggler, those give us a result that the wiggler has a ability of self-focusing, and can be applied in the linearly polarized PEL experiment.
In free electron laser with a long, linear wiggler, the magnetic field at the entrance of wiggler and the external focusing required to deep the electron beam from dispersing can determine the character of the electron orbits and seriously influence the PEL gain. To obtain good results in PEL experiments, it is necessary to investigate the linearly polarized wiggler with good magnetic field at the entrance and self-focusing.
In this paper, it is researched in details that the entrance magnetic field and self-focusing of the linearly polarized wiggler produced by doubje bifilar helix lines. (1) The integral formula of the magnetic field on Z axis of the wiggler is derived, the prediction by the formula is good with the experiment, the results show that the field symmetry is better than the bifilar helix wiggler's. (2) According to Lorentz equation, we have derived the electron trajactory equations with the stable motions, and the formula about the threshold transport e-beam current and the wiggler peak field, simulated the orbits of the electron at edge in the wiggler, those give us a result that the wiggler has a ability of self-focusing, and can be applied in the linearly polarized PEL experiment.
1993,
05: 290-296.
Abstract:
This paper discribe the two -dimention analystic relationship of hybrid microwiggler field, and analyse the possibility of the hybrid microwiggler with high field. It is shown that the hybrid microwiggler with 10mm period and 5mm gap may generate 0.75T magnetic field on axis before the saturation of the poles. Moreover, we have given a discussion of several new methods for obtaining the high field and the results of the ecperimental models.
This paper discribe the two -dimention analystic relationship of hybrid microwiggler field, and analyse the possibility of the hybrid microwiggler with high field. It is shown that the hybrid microwiggler with 10mm period and 5mm gap may generate 0.75T magnetic field on axis before the saturation of the poles. Moreover, we have given a discussion of several new methods for obtaining the high field and the results of the ecperimental models.
1993,
05: 297-302.
Abstract:
This paper reports the work done to define the characteristics of a variety of wide spectral mirror coatings for a DF laser optical system. In particular, dielectric enhanced metallic mirrors have been designed and fabricated. The results of reflectivities of 0.994 or greater for 3.8μm and average reflectance of more than 0.95 at visible region and 8 - 14μm infrared have been acquired. Reflectance measurements are presented along with environmental testing to demonstrade the performance of these mirror coatings.
This paper reports the work done to define the characteristics of a variety of wide spectral mirror coatings for a DF laser optical system. In particular, dielectric enhanced metallic mirrors have been designed and fabricated. The results of reflectivities of 0.994 or greater for 3.8μm and average reflectance of more than 0.95 at visible region and 8 - 14μm infrared have been acquired. Reflectance measurements are presented along with environmental testing to demonstrade the performance of these mirror coatings.
1993,
05: 303-308.
Abstract:
The effect of temperature rise and wavefront distortion of window materials on the beam divergent angle is calculated in the case of three kinds of output powers (103W, 104W, 105W ) with CaF2 output window of a DF laser as example in this paper.
The effect of temperature rise and wavefront distortion of window materials on the beam divergent angle is calculated in the case of three kinds of output powers (103W, 104W, 105W ) with CaF2 output window of a DF laser as example in this paper.
1993,
05: 309-316.
Abstract:
In this paper, we briefly introduce the basic principle, the construction and the data processing of a hard X-ray spectrometer (FFS) composed of filtered detector arrays. Finally, the typical experimental results of the hard X -ray spectrum measurement are given.
In this paper, we briefly introduce the basic principle, the construction and the data processing of a hard X-ray spectrometer (FFS) composed of filtered detector arrays. Finally, the typical experimental results of the hard X -ray spectrum measurement are given.
1993,
05: 317-319.
Abstract:
The mechanism of x -ray emission in hohlraum targets was experimentally studied with three soft x-ray energy spectrometers and a pinhole camera. The principal mechanism of x-ray emission was given.
The mechanism of x -ray emission in hohlraum targets was experimentally studied with three soft x-ray energy spectrometers and a pinhole camera. The principal mechanism of x-ray emission was given.
