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RSS1997 Vol. 09, No. 03
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1997,
09.
Abstract:
The coupling effect of high-intensity nanosecond laser pulse with A1 or CH plasamas are studied using the hydrodynamical equations which are one-dimesional, doubl-tem-perature, single-fluid. The effects of laser intensity and wavelength on energy deposition in the target surface and plasma parametes are numerically investigated.
The coupling effect of high-intensity nanosecond laser pulse with A1 or CH plasamas are studied using the hydrodynamical equations which are one-dimesional, doubl-tem-perature, single-fluid. The effects of laser intensity and wavelength on energy deposition in the target surface and plasma parametes are numerically investigated.
1997,
09.
Abstract:
A kind of GaAs photoconductive detector (PCD) was used to measure the radiation pulse signal of fusion neutron.According to the PIN detection system, the GaAs direct radiation sensitivity by １４．１MeV neutron have calculated, the results is 1.5(10E-20 (1±１８％）C(cm(cm/mm(mm(mm.The difference of the measured result and the pcalculated value, the foreign report is very small respectively.
A kind of GaAs photoconductive detector (PCD) was used to measure the radiation pulse signal of fusion neutron.According to the PIN detection system, the GaAs direct radiation sensitivity by １４．１MeV neutron have calculated, the results is 1.5(10E-20 (1±１８％）C(cm(cm/mm(mm(mm.The difference of the measured result and the pcalculated value, the foreign report is very small respectively.
1997,
09.
Abstract:
Plasma state and motion in gold cylinders, which were irradiated by 0.35(m laser,are experimentally investigated. Some measures suchas CH liner and separate foils to hold back the plasma motion in a cylinder also are tested in experiments.The results obtained may be helpful for control radiation environment in a hohlraum.
Plasma state and motion in gold cylinders, which were irradiated by 0.35(m laser,are experimentally investigated. Some measures suchas CH liner and separate foils to hold back the plasma motion in a cylinder also are tested in experiments.The results obtained may be helpful for control radiation environment in a hohlraum.
1997,
09.
Abstract:
The plasma state and the gain region produced by the oblique-incidence laser on Ge target are studied and are compared with that produced by the vertical one. As a result of study, the absorption efficiency of the pumping energy turns far smaller, the plasma state changes remarkable and the gain region becomes much narrower when incident angle is greater than 30.
The plasma state and the gain region produced by the oblique-incidence laser on Ge target are studied and are compared with that produced by the vertical one. As a result of study, the absorption efficiency of the pumping energy turns far smaller, the plasma state changes remarkable and the gain region becomes much narrower when incident angle is greater than 30.
1997,
09.
Abstract:
In this paper, the dependence of discharge character of plasma generator on the geometric scale of capillary and the initial charge voltage of PFN has been studied in experiments and the results wilｌ contribute to improve the design of plasma generator and increase it's discharge efficiency.
In this paper, the dependence of discharge character of plasma generator on the geometric scale of capillary and the initial charge voltage of PFN has been studied in experiments and the results wilｌ contribute to improve the design of plasma generator and increase it's discharge efficiency.
1997,
09.
Abstract:
Pulse shaping is the important methods to get high compssion ratio. In this paper, a temperature pulse shaping curve suitable to SG-Ⅲ Facility is obtained by numerical simulation.
Pulse shaping is the important methods to get high compssion ratio. In this paper, a temperature pulse shaping curve suitable to SG-Ⅲ Facility is obtained by numerical simulation.
1997,
09.
Abstract:
The output characteristics of a Nelike Ti single Xray laser produced using a ppulse technique are measured at Xingguang laser facility. A highly sensitive and spatial resolved detector consisting of X-ray multilayer mirrors, Al filter and an XUV CCD camera is used in the experiment. The spatial intensity distributions of the Nelike Ti Xray laser in near field and the plane 32mm from the laser output end (quasi far field) have been obtained. The dimension of the strongest intensity region is given to be about 72μm×３１μm. Also, the divergences of the laser beam are gained. The divergence in the direction perpendicular to the target surface is about 4mrad and in the parallel direction about 9mrad.
The output characteristics of a Nelike Ti single Xray laser produced using a ppulse technique are measured at Xingguang laser facility. A highly sensitive and spatial resolved detector consisting of X-ray multilayer mirrors, Al filter and an XUV CCD camera is used in the experiment. The spatial intensity distributions of the Nelike Ti Xray laser in near field and the plane 32mm from the laser output end (quasi far field) have been obtained. The dimension of the strongest intensity region is given to be about 72μm×３１μm. Also, the divergences of the laser beam are gained. The divergence in the direction perpendicular to the target surface is about 4mrad and in the parallel direction about 9mrad.
1997,
09.
Abstract:
The distribution of Hα spectral lineshape has been derived from the surface of limiter in HT-6M torkamak, with Optical System Mutichannel. The energy distribution of hydrogen atoms has been directly derived from the distribution of Hα lineshape, Main molecular processes at plasma edge have been discussed. Plasma ion temperature has been obtained from fitting remote wing of the distrubution of Hα lineshape with Gaussian function.
The distribution of Hα spectral lineshape has been derived from the surface of limiter in HT-6M torkamak, with Optical System Mutichannel. The energy distribution of hydrogen atoms has been directly derived from the distribution of Hα lineshape, Main molecular processes at plasma edge have been discussed. Plasma ion temperature has been obtained from fitting remote wing of the distrubution of Hα lineshape with Gaussian function.
1997,
09.
Abstract:
In this paper, the nonmetal possibility of rotating disk type SOG is studied experimentally. The results indicated that it is possible to use fiberglass as rotating disk to repsent metal disk such as Ni disk and stainless steel.
In this paper, the nonmetal possibility of rotating disk type SOG is studied experimentally. The results indicated that it is possible to use fiberglass as rotating disk to repsent metal disk such as Ni disk and stainless steel.
1997,
09.
Abstract:
The measuring methods and results of pulse width (FWHM), divergence and linewidth of laser output from a 10E10W tunable Nd:glass laser system are introduced ．
The measuring methods and results of pulse width (FWHM), divergence and linewidth of laser output from a 10E10W tunable Nd:glass laser system are introduced ．
1997,
09.
Abstract:
The diagnostics of the chemical oxygen-iodine laser (COIL) device are discussed systematically. It is divided into several diagnostic subsystems such as flow diagnostic, oxygen-iodine flow mixing diagnostic,gain medium diagnostic and resonator diagnostic. The requirement of every diagtic parameter, their measure principles and metnods, are discussed sytematically, some diagnostic examples are also given respectively.
The diagnostics of the chemical oxygen-iodine laser (COIL) device are discussed systematically. It is divided into several diagnostic subsystems such as flow diagnostic, oxygen-iodine flow mixing diagnostic,gain medium diagnostic and resonator diagnostic. The requirement of every diagtic parameter, their measure principles and metnods, are discussed sytematically, some diagnostic examples are also given respectively.
1997,
09.
Abstract:
The thin film design, the coating materials selection, the production technology for reflect coatings, substrate fabrication, optical performatance measuring, and the damage and heat deformation of reflectors subjected to the high power have been reported to the short wavelength chemical laser system high reflector in the this paper.
The thin film design, the coating materials selection, the production technology for reflect coatings, substrate fabrication, optical performatance measuring, and the damage and heat deformation of reflectors subjected to the high power have been reported to the short wavelength chemical laser system high reflector in the this paper.
1997,
09.
Abstract:
The basic principle and method using Hartmann-shack method to calibrate plane beam is derived in this paper. Some experiments are also done to calibrate incident beam. The incident beam going through the subapertures of Hartmann system projects on the focal plane to form light spots. If the average value of space between the projecting neighbouring light spot centres is larger than the ideal plane beam case, the calibrated beam is divergent; in the smaller case, the calibraged beam is convergent. The calibration method has the advantages of simple principle and convenient operation
The basic principle and method using Hartmann-shack method to calibrate plane beam is derived in this paper. Some experiments are also done to calibrate incident beam. The incident beam going through the subapertures of Hartmann system projects on the focal plane to form light spots. If the average value of space between the projecting neighbouring light spot centres is larger than the ideal plane beam case, the calibrated beam is divergent; in the smaller case, the calibraged beam is convergent. The calibration method has the advantages of simple principle and convenient operation
1997,
09.
Abstract:
The modes of stable resonator which consist of thermal distorted flat and concave mirror are investigated with Fox-Li iteration. The amplitude and phase distrigutions on the output mirror are psented. For this stable resontor, in orderto erase the mode's distribution the thermal distortion of both mirror distortion is greater than 1/10 wavelength, there would be no fundamental mode. It is also pointed out that there are more serious mirror thermal distortion in fringe cooling mirror in high power laser and then the laser beam quality is lowered badly.
The modes of stable resonator which consist of thermal distorted flat and concave mirror are investigated with Fox-Li iteration. The amplitude and phase distrigutions on the output mirror are psented. For this stable resontor, in orderto erase the mode's distribution the thermal distortion of both mirror distortion is greater than 1/10 wavelength, there would be no fundamental mode. It is also pointed out that there are more serious mirror thermal distortion in fringe cooling mirror in high power laser and then the laser beam quality is lowered badly.
1997,
09.
Abstract:
The theme discuss distortion of active cooling copper mirror theoretically and experimantally. Thereby, a serious multilayer mirrors are designed. Among those, a mutilayer mirror with circular coolant channel is better. Its total distortion only 0.10μm, when the pssure of coolant is 0.13MPa, the absorbed laser power is 86.9W. It is about 1/40 of the distortion of the traditional active cooling mirror under the same conditions.
The theme discuss distortion of active cooling copper mirror theoretically and experimantally. Thereby, a serious multilayer mirrors are designed. Among those, a mutilayer mirror with circular coolant channel is better. Its total distortion only 0.10μm, when the pssure of coolant is 0.13MPa, the absorbed laser power is 86.9W. It is about 1/40 of the distortion of the traditional active cooling mirror under the same conditions.
1997,
09.
Abstract:
Using the integrated formula of Bessel function which is based on the distribution of field, the stored energy, the dissipation power of average for time expssion, a factor of cold quality is determined. It shows that the expssion of the rotation TMn10 mode for magnicon agrees better with experimental date. In order to checking, its mode is obtained.
Using the integrated formula of Bessel function which is based on the distribution of field, the stored energy, the dissipation power of average for time expssion, a factor of cold quality is determined. It shows that the expssion of the rotation TMn10 mode for magnicon agrees better with experimental date. In order to checking, its mode is obtained.
1997,
09.
Abstract:
In order to generate shorter wavelength FEL, and electronic bunch has to be coupled with the extrnal powerful laser pulses in optical klystron. In this process the coherent harmonic radiation will be generated. It is necessary that the electronic bunch and laser pulses are synchronic in both time and space. The synchronization in space can be realized by adjusting the light road of the external laser. In this paper, a method is suggested to obtain the synchronization in time.
In order to generate shorter wavelength FEL, and electronic bunch has to be coupled with the extrnal powerful laser pulses in optical klystron. In this process the coherent harmonic radiation will be generated. It is necessary that the electronic bunch and laser pulses are synchronic in both time and space. The synchronization in space can be realized by adjusting the light road of the external laser. In this paper, a method is suggested to obtain the synchronization in time.
1997,
09.
Abstract:
The cut method for Gussian beam having axisymmetry is discussed in detail and the expssion for the cut factor is defined in this paper. It is shown that when the factor is equal to 0.9, the cutbeam emittance is twice as large as its rootmeansquare (rms) emittance and the factor is only equal to 0.59 if the cutbeam emittance is equal to its rms emittance. The probability function for the fourdimensional new variables are derived and the sample procedures for them are simply described as well．
The cut method for Gussian beam having axisymmetry is discussed in detail and the expssion for the cut factor is defined in this paper. It is shown that when the factor is equal to 0.9, the cutbeam emittance is twice as large as its rootmeansquare (rms) emittance and the factor is only equal to 0.59 if the cutbeam emittance is equal to its rms emittance. The probability function for the fourdimensional new variables are derived and the sample procedures for them are simply described as well．
1997,
09.
Abstract:
Whether the energy of the electron beam from the irradiation LINAC is stable or not depents on the stability of the operating frequency of the power source. The dispersion and the slight jump of the spectrum of the mabnetron in a short time causes to decrease the controlling accuracy of the frequency stabilization system. Finally, the scanning uniformity of the electron beam descents. The adaptive linear element (ADALINE) and the noise canceling technique are introduced to eliminate the influence of the dispersion and the slight jump of the spectrum on the frequency stability on long time. Thus the scanning uniformity of the electron beam can be assuured.
Whether the energy of the electron beam from the irradiation LINAC is stable or not depents on the stability of the operating frequency of the power source. The dispersion and the slight jump of the spectrum of the mabnetron in a short time causes to decrease the controlling accuracy of the frequency stabilization system. Finally, the scanning uniformity of the electron beam descents. The adaptive linear element (ADALINE) and the noise canceling technique are introduced to eliminate the influence of the dispersion and the slight jump of the spectrum on the frequency stability on long time. Thus the scanning uniformity of the electron beam can be assuured.
1997,
09.
Abstract:
The FD-TD method with FFT is applied to calculate the eigenfrequencies and eige nfield distribution of a resonant cavity which is an appropriately shorted periodic slow wave circuit of N periods at both ends, the synthetic technique based on the intrinsic characteristics of spatially periodic structure is used to derive the complete dispersion relation using a few specially measured resonances. The novel method was sucessfully applied to analyze the high frequency characteristics of the coaxial relativistic backward oscillator and is applicable to slow wave structures of arbitrary geometry.
The FD-TD method with FFT is applied to calculate the eigenfrequencies and eige nfield distribution of a resonant cavity which is an appropriately shorted periodic slow wave circuit of N periods at both ends, the synthetic technique based on the intrinsic characteristics of spatially periodic structure is used to derive the complete dispersion relation using a few specially measured resonances. The novel method was sucessfully applied to analyze the high frequency characteristics of the coaxial relativistic backward oscillator and is applicable to slow wave structures of arbitrary geometry.
1997,
09.
Abstract:
In this paper a new idea for beam-pbunching in RFA was proposed. Without any applied RF power source, beam pbunching can be carried out. The bunching device is the same as the conventional pbuncher in structure, but obeys the conditions as follows:(1)a considerable detuning between the repetition of the beam bunch and the characteristic frequency of the cavity; (2) the characteristic frequency of the cavity is higher; (3) resistivity of the material of cavity is higher. A set of experimental check was performed on the corresponding equipment built in CIAE. A proper bunching was observed.
In this paper a new idea for beam-pbunching in RFA was proposed. Without any applied RF power source, beam pbunching can be carried out. The bunching device is the same as the conventional pbuncher in structure, but obeys the conditions as follows:(1)a considerable detuning between the repetition of the beam bunch and the characteristic frequency of the cavity; (2) the characteristic frequency of the cavity is higher; (3) resistivity of the material of cavity is higher. A set of experimental check was performed on the corresponding equipment built in CIAE. A proper bunching was observed.
1997,
09.
Abstract:
The performance process of indirectly feeding, helical magnetic flux compssion generator are studied with five-section model. The dependences of the system magnetic flux multiplication and energy multiplication ratios on construction parameters are analyzed. The effects of tapering angle, misalignment between armature and coil are also discussed.
The performance process of indirectly feeding, helical magnetic flux compssion generator are studied with five-section model. The dependences of the system magnetic flux multiplication and energy multiplication ratios on construction parameters are analyzed. The effects of tapering angle, misalignment between armature and coil are also discussed.
1997,
09.
Abstract:
The new theory on the bunch lengthening psented in the paper is used to explain the experimental result of the multi-bunch lengthening in Hefei Light Source(HLS).It proves that the interaction between the beam and the RF cavity is the most important factor to the bunch lengthening in HLS.It also proves that the narrow band impedance plays and important role in bunch lengthening.
The new theory on the bunch lengthening psented in the paper is used to explain the experimental result of the multi-bunch lengthening in Hefei Light Source(HLS).It proves that the interaction between the beam and the RF cavity is the most important factor to the bunch lengthening in HLS.It also proves that the narrow band impedance plays and important role in bunch lengthening.
1997,
09.
Abstract:
An insert device TOK has been built up and mounted on the storage ring of NSRL. The magnetic field distribution of TOK is additionally measured, and the harmonic components of magnetic field distribution in strength were analysed. And the integral field distribution is measured, and the investigation of the origin of the integral variation is taken. The uniformity of the transvers distribution of the field is checked to provide the experimental data for the coherent harmonic generation and FEL investigation in the future. Finally, numerical simulation on spontaneouse radiation from TOK is taken with the measured data, and the result illustrates that the TOK is taken with the measured data, and the result illustrates that the TOK can satisfy the experimental requirement.
An insert device TOK has been built up and mounted on the storage ring of NSRL. The magnetic field distribution of TOK is additionally measured, and the harmonic components of magnetic field distribution in strength were analysed. And the integral field distribution is measured, and the investigation of the origin of the integral variation is taken. The uniformity of the transvers distribution of the field is checked to provide the experimental data for the coherent harmonic generation and FEL investigation in the future. Finally, numerical simulation on spontaneouse radiation from TOK is taken with the measured data, and the result illustrates that the TOK is taken with the measured data, and the result illustrates that the TOK can satisfy the experimental requirement.
1997,
09.
Abstract:
Ａ method of designing a low impedance, lumped parameter, nonuniform capacitance pulse forming network(PFN) to fit in with the needs of a high voltage, large turns ratio ,low impedance pulse transformer with large leakage inductance are introduced.Combining with computer optimization design, a 100kV, 1.4Ω, 6 stage lumped parameter Blumlein network has been achieved, shortened the rise time and fall time of output pulses, improved pulse waveform and successfully used in a 500kV long pulse accelerator.
Ａ method of designing a low impedance, lumped parameter, nonuniform capacitance pulse forming network(PFN) to fit in with the needs of a high voltage, large turns ratio ,low impedance pulse transformer with large leakage inductance are introduced.Combining with computer optimization design, a 100kV, 1.4Ω, 6 stage lumped parameter Blumlein network has been achieved, shortened the rise time and fall time of output pulses, improved pulse waveform and successfully used in a 500kV long pulse accelerator.
1997,
09.
Abstract:
The research on the transverse impedance measurements of a linear induction accelerator cavity is psented. The device is transformed into coaxial (TEM) configuration by inserting two parallel off-axis wire conductors. Scattering parameters are measured using a network analyzer (HP8753D) with a computer as a controller. By comparing and colculating the shunt impedance is found. In order to eliminate the multiple reflection caused by nonmatched 50( coaxial transmission line to the beam pipe end, time-filtering is used. Analyzing of the measurement error is psented too
The research on the transverse impedance measurements of a linear induction accelerator cavity is psented. The device is transformed into coaxial (TEM) configuration by inserting two parallel off-axis wire conductors. Scattering parameters are measured using a network analyzer (HP8753D) with a computer as a controller. By comparing and colculating the shunt impedance is found. In order to eliminate the multiple reflection caused by nonmatched 50( coaxial transmission line to the beam pipe end, time-filtering is used. Analyzing of the measurement error is psented too
1997,
09.
Abstract:
Thermal failure of SiC particulate reinforced 6061 aluminium alloy composites induced by the coupled loading with both laser thermal shocking and mechanical loading has been investigated. In the test, a pulsed Nd:glass laser beam is used with duration 1.0ms and 250(s, The notched-tip region of the specimen is subjected to laser beam rapid heating. The crack-tip process zone development and the microcracks formation are macroscopically and microscopically observed. It is found that the mechanisms for the cracks formation are different from those for the crack expansion.
Thermal failure of SiC particulate reinforced 6061 aluminium alloy composites induced by the coupled loading with both laser thermal shocking and mechanical loading has been investigated. In the test, a pulsed Nd:glass laser beam is used with duration 1.0ms and 250(s, The notched-tip region of the specimen is subjected to laser beam rapid heating. The crack-tip process zone development and the microcracks formation are macroscopically and microscopically observed. It is found that the mechanisms for the cracks formation are different from those for the crack expansion.
1997,
09.
Abstract:
The effects of black paint on laser induced shock waves in the aluminum and copper targets are introduced when the targets are irradiated by laser pulses of 33ns duration, at laser power density around 10E９W/cm(cm， and wavelength 1.06μｍ. The direct shock pssure measurements show that the black paint can increase the shock pssure amplitude and affect the shock evolution characteristics as well. The black paint can also protect target surfaces from laser ablation by comparing the SEM photographs of the target surfaces with that without black paint．
The effects of black paint on laser induced shock waves in the aluminum and copper targets are introduced when the targets are irradiated by laser pulses of 33ns duration, at laser power density around 10E９W/cm(cm， and wavelength 1.06μｍ. The direct shock pssure measurements show that the black paint can increase the shock pssure amplitude and affect the shock evolution characteristics as well. The black paint can also protect target surfaces from laser ablation by comparing the SEM photographs of the target surfaces with that without black paint．
1997,
09.
Abstract:
On the basis of Gurney equation and the equation of state considering phase transition for metals, a model to calculate the movement of the laser driven flyer is proposed in this paper.This model can be used to determine parameters related with critical initiation of explosive, such as deposited laser energy, thickness of ablation layer and flyer, flying distance and so on. The calculated results are consistent with the experiments. Further considerations of ionization, ablation and two dimensional effects are possible to be included in the model.
On the basis of Gurney equation and the equation of state considering phase transition for metals, a model to calculate the movement of the laser driven flyer is proposed in this paper.This model can be used to determine parameters related with critical initiation of explosive, such as deposited laser energy, thickness of ablation layer and flyer, flying distance and so on. The calculated results are consistent with the experiments. Further considerations of ionization, ablation and two dimensional effects are possible to be included in the model.
1997,
09.
Abstract:
IR thermal imaging system is used to measure the front and rear surface temperature distribution of the coated metal (30CrMnSiA steel and LF6M alloy) irradiated by repetitive frequency (RF) laser. The characteristics of temperature increasement with laser irradiation time are analyzed in this paper. The experiment results show that the rear surface temperature of metal is mainly dependent on laser average power when target thickness is more than 1.6mm. The higher the laser pulse frequency is, the higher the efficiency of laser heating metal has. RF laser heating material is better than CW laser does．
IR thermal imaging system is used to measure the front and rear surface temperature distribution of the coated metal (30CrMnSiA steel and LF6M alloy) irradiated by repetitive frequency (RF) laser. The characteristics of temperature increasement with laser irradiation time are analyzed in this paper. The experiment results show that the rear surface temperature of metal is mainly dependent on laser average power when target thickness is more than 1.6mm. The higher the laser pulse frequency is, the higher the efficiency of laser heating metal has. RF laser heating material is better than CW laser does．
1997,
09.
Abstract:
The laser damage of quadrant detectors has been investigated experimently, and shows that it is equal to add a fixed angle bias when the damaged detector is used to detect space angle. The influences of laser damage on the optical guidance is also discussed.
The laser damage of quadrant detectors has been investigated experimently, and shows that it is equal to add a fixed angle bias when the damaged detector is used to detect space angle. The influences of laser damage on the optical guidance is also discussed.
1997,
09.
Abstract:
A big electric-current apparatus which can output current of 0.15-0.25kA is discussed, a LY12 aluminium plate is heated by big electric-current, a heating, a heating rate from 27 to 7430℃/s can be obtained, the real-time recording technique of dynamic moire interferometry fringes under high heating rate by a high speed camera is studied, a recording frequency of 1000frame in a second is obtained. The temperature rising effect of structure irradiated by CW high power laser is simulated using both technology. It provides a new way to research some fundamental problems of structural mechanism of fracture. The experimental result indicates that it is possible for moire interferometry to measure dynamic deformation under high temperature condiation.
A big electric-current apparatus which can output current of 0.15-0.25kA is discussed, a LY12 aluminium plate is heated by big electric-current, a heating, a heating rate from 27 to 7430℃/s can be obtained, the real-time recording technique of dynamic moire interferometry fringes under high heating rate by a high speed camera is studied, a recording frequency of 1000frame in a second is obtained. The temperature rising effect of structure irradiated by CW high power laser is simulated using both technology. It provides a new way to research some fundamental problems of structural mechanism of fracture. The experimental result indicates that it is possible for moire interferometry to measure dynamic deformation under high temperature condiation.
