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RSS1999 Vol. 11, No. 03
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1999,
11.
Abstract:
This paper describes the princi ple and specification of the beam current transformer(BCT). Sensitivity is equal to 0.47V/A. Frequency response is great than 100MHz.Drop of the flat top is les s than 0.4%/μs.The beam current transformer has been used to measure macropulse electron beam currents produced by 30MeV electron linear a ccelerator and the macropulse beam current waveforms measured by BCT are also given.
This paper describes the princi ple and specification of the beam current transformer(BCT). Sensitivity is equal to 0.47V/A. Frequency response is great than 100MHz.Drop of the flat top is les s than 0.4%/μs.The beam current transformer has been used to measure macropulse electron beam currents produced by 30MeV electron linear a ccelerator and the macropulse beam current waveforms measured by BCT are also given.
1999,
11.
Abstract:
Based on the Zernike method of the zeroorder spectral phase modification a single expanded laser beam can be converted into arbitrary illuminated shape with theoretical 100% efficiency with a pair of spec ific binary phase gratings. We have obtained the relation among the phases and t he phasemodulated space factor of the aperture.Experimental demonstration of 3/4 space factor, 3×3π phasemod ulatedsquare areas with 89% efficiency is given．
Based on the Zernike method of the zeroorder spectral phase modification a single expanded laser beam can be converted into arbitrary illuminated shape with theoretical 100% efficiency with a pair of spec ific binary phase gratings. We have obtained the relation among the phases and t he phasemodulated space factor of the aperture.Experimental demonstration of 3/4 space factor, 3×3π phasemod ulatedsquare areas with 89% efficiency is given．
1999,
11.
Abstract:
In order to measure prec isely the roughness of capsule surface，a 4π turning device matching with AFM for microsphere is developed．The shell mounted on the 4π turning device can be rotated in any angle, and any where of the target surface can be measured. With this equipment，various capsules are investigated and discussed．
In order to measure prec isely the roughness of capsule surface，a 4π turning device matching with AFM for microsphere is developed．The shell mounted on the 4π turning device can be rotated in any angle, and any where of the target surface can be measured. With this equipment，various capsules are investigated and discussed．
1999,
11.
Abstract:
The influence of COIL operation parameters on the laser perfor mance is studied numerically on the basis of an approximative physical model with the key computation of solving NavierStokes equations. Related results are given and discussed, which are of worth for analyzing experiments and choosing operation parameters in COIL design．
The influence of COIL operation parameters on the laser perfor mance is studied numerically on the basis of an approximative physical model with the key computation of solving NavierStokes equations. Related results are given and discussed, which are of worth for analyzing experiments and choosing operation parameters in COIL design．
1999,
11.
Abstract:
Recently there has been considerab le interested in the Thomson scattering between high energy laser and relativist ic electron beam, and a new kind of Xray source named laser synchrotron source (LSS) has been discussed based on this principle. Some theoretical results of the experiment are given out in this paper, which show the promising future of LSS and the feasibility of the experiment.
Recently there has been considerab le interested in the Thomson scattering between high energy laser and relativist ic electron beam, and a new kind of Xray source named laser synchrotron source (LSS) has been discussed based on this principle. Some theoretical results of the experiment are given out in this paper, which show the promising future of LSS and the feasibility of the experiment.
1999,
11.
Abstract:
The paper has 3D nonlinear analysis for TWTs. Based on macroparticle model, the electron beam can be subdivided into 3D Macroparticles to calculate space charge forces using Green's function methods, and 3D large signal working equations are obtained. The numerical results for a uniform magnetic focusing field indicates that, in 3D numerical analysis,3D spacecharge forces can be substituted by 2D's with little influence on the numerical results, which greatly decreases computing hours so that 3D computer program can be easily used．
The paper has 3D nonlinear analysis for TWTs. Based on macroparticle model, the electron beam can be subdivided into 3D Macroparticles to calculate space charge forces using Green's function methods, and 3D large signal working equations are obtained. The numerical results for a uniform magnetic focusing field indicates that, in 3D numerical analysis,3D spacecharge forces can be substituted by 2D's with little influence on the numerical results, which greatly decreases computing hours so that 3D computer program can be easily used．
1999,
11.
Abstract:
SBand standing wave elec tron linacs have got wideranging application for industry nondestructive testing and formed varied kinds of products. Xband electron linac for NDT has been developed by Schonberg Company USA in 1985. Because of bigger structure of S-band linac and difficult machining of XBand linac, an Cband portable linac for NDT has be developed in CIAE at pre sent, a whole sealed vacuum accelerating tuber will be given here. It consists of 4 cavities, the pha se velocity of the first two cavities is 0.5 and 0.9, respectively, and that of the second two cavities is 1. The high power testing proved that the design of the accelerating tuber is good for 1.5MeV electron linac for NDT.
SBand standing wave elec tron linacs have got wideranging application for industry nondestructive testing and formed varied kinds of products. Xband electron linac for NDT has been developed by Schonberg Company USA in 1985. Because of bigger structure of S-band linac and difficult machining of XBand linac, an Cband portable linac for NDT has be developed in CIAE at pre sent, a whole sealed vacuum accelerating tuber will be given here. It consists of 4 cavities, the pha se velocity of the first two cavities is 0.5 and 0.9, respectively, and that of the second two cavities is 1. The high power testing proved that the design of the accelerating tuber is good for 1.5MeV electron linac for NDT.
1999,
11.
Abstract:
The analysis a nd discussion of the effect of the undulator magnetic field error on the modulat ion of the electron beam energy in an optical klystron are presented in this pap er. The results show th at the effects of the magnetic field error on the energy modulation of the electron beam can be negligible.
The analysis a nd discussion of the effect of the undulator magnetic field error on the modulat ion of the electron beam energy in an optical klystron are presented in this pap er. The results show th at the effects of the magnetic field error on the energy modulation of the electron beam can be negligible.
1999,
11.
Abstract:
Status of developing a coated ceramic chamber for the new injection bu mp system of the HLS ring is presented. Shielding effects of the coating film to the pulsed magne tic field which penetrates through the chamber are analyzed and calculated.Several coating schemes are studied and discussed. Orbit perturbation caused by the error field during inje ction is calculated by tracking code.The maximum allowed error is determined．
Status of developing a coated ceramic chamber for the new injection bu mp system of the HLS ring is presented. Shielding effects of the coating film to the pulsed magne tic field which penetrates through the chamber are analyzed and calculated.Several coating schemes are studied and discussed. Orbit perturbation caused by the error field during inje ction is calculated by tracking code.The maximum allowed error is determined．
1999,
11.
Abstract:
The object is to analyze theoretically and test experimentally the pro pagation characteristic of u ltraviolet laser pulse in stepindex multimode fiber. Experimental results sho w that with the picosecondlevel output laser pulse from fiber, the power supp ortability of that fiber is confined. on the other hand, when nanosecondlevel output laser pulse passes tens of meters through fiber, It is a useable propag ation medium.
The object is to analyze theoretically and test experimentally the pro pagation characteristic of u ltraviolet laser pulse in stepindex multimode fiber. Experimental results sho w that with the picosecondlevel output laser pulse from fiber, the power supp ortability of that fiber is confined. on the other hand, when nanosecondlevel output laser pulse passes tens of meters through fiber, It is a useable propag ation medium.
1999,
11.
Abstract:
Effects of postgrowth annealing on optical properties of single layer InxGa1xAs quantum dots with different indium fraction (x),embedded in a GaAs or an Al0.15Ga0.85As matrix res pectively,have been investigated. Annealing leads to narrowing of line width and different blue shifts for different indium fraction.
Effects of postgrowth annealing on optical properties of single layer InxGa1xAs quantum dots with different indium fraction (x),embedded in a GaAs or an Al0.15Ga0.85As matrix res pectively,have been investigated. Annealing leads to narrowing of line width and different blue shifts for different indium fraction.
1999,
11.
Abstract:
In third harmonic generation, it is v ery important to select the parameters of the generator. In this paper, we optim ized the thickness of the doublers and triplers, mismatch angles and other param eters of Ⅰ／Ⅱ angledetuning and Ⅱ／Ⅱ polarizationmismatch third harmonic generation schemes by numerical calculation way. We also give the tripling effi ciency curves which the pulse shape of the input intensity is flat in space and time around 5.0 GW/cm2.
In third harmonic generation, it is v ery important to select the parameters of the generator. In this paper, we optim ized the thickness of the doublers and triplers, mismatch angles and other param eters of Ⅰ／Ⅱ angledetuning and Ⅱ／Ⅱ polarizationmismatch third harmonic generation schemes by numerical calculation way. We also give the tripling effi ciency curves which the pulse shape of the input intensity is flat in space and time around 5.0 GW/cm2.
1999,
11.
Abstract:
The formula of gas pressure inside HGM (hollow glass microspher es) wit h thin wall during procedures of gas filling at one step or steps and those of gas leak rate and gas retention halflife of HGM were derived.The confinement conditions to avoid HG M failure in the procedure of gas fill at steps were developed. Then the permeabi lity of D2 through HGM was experimentally measured,and the results were in good agreement with the calculated ones.
The formula of gas pressure inside HGM (hollow glass microspher es) wit h thin wall during procedures of gas filling at one step or steps and those of gas leak rate and gas retention halflife of HGM were derived.The confinement conditions to avoid HG M failure in the procedure of gas fill at steps were developed. Then the permeabi lity of D2 through HGM was experimentally measured,and the results were in good agreement with the calculated ones.
1999,
11.
Abstract:
The performancs of luminescent glass and fiberoptic luminescent glass activated by terbium are presented. The principal advantages of luminescent glass and fiberoptic scintillators are im proved, such as spatial resolution and increased Xray absorption compared to t raditional phosphor screens in digital realtime radiography systems, so, it is specially suitable for high energy Xray realtime radiography systems.
The performancs of luminescent glass and fiberoptic luminescent glass activated by terbium are presented. The principal advantages of luminescent glass and fiberoptic scintillators are im proved, such as spatial resolution and increased Xray absorption compared to t raditional phosphor screens in digital realtime radiography systems, so, it is specially suitable for high energy Xray realtime radiography systems.
1999,
11.
Abstract:
The expressions or values of dis charge circle parameters for coppervapor laser are presented. Combined with the coppervapor laser kinetic model, the plasma resistance characteristics have been studied as the plasma parameters in the discharge tube changing, and they a re compared with the plasma resistance characteristics deduced from the static p lasma parameters in discharge tube.
The expressions or values of dis charge circle parameters for coppervapor laser are presented. Combined with the coppervapor laser kinetic model, the plasma resistance characteristics have been studied as the plasma parameters in the discharge tube changing, and they a re compared with the plasma resistance characteristics deduced from the static p lasma parameters in discharge tube.
1999,
11.
Abstract:
The results of 3D raytracing analysis of roof and flat reflector profiles are presented in this paper. The Monte Carlo simulation show that the rooftype reflector gi ves a 63% geometrical transfer efficiency and the flat shapetype reflector gives a lower transferef ficiency (＜56%),while both reflector profiles have similar pumping uniformity ．
The results of 3D raytracing analysis of roof and flat reflector profiles are presented in this paper. The Monte Carlo simulation show that the rooftype reflector gi ves a 63% geometrical transfer efficiency and the flat shapetype reflector gives a lower transferef ficiency (＜56%),while both reflector profiles have similar pumping uniformity ．
1999,
11.
Abstract:
The R matrix approximation is used to compute the excitation collision strength of electron impact on Lilike C with the configuration interaction wavefunctions, in which the configuration inte ractions of an innershell electron excitation are included. For transition 1s ２２s２S１s１２p２Po,the result in this paper is a litt le smaller than that of the close coupling approximation and a little larger than that of CoulombBornexchange approximation，and accords with that of the experiment except that nearer excita tion threshold.
The R matrix approximation is used to compute the excitation collision strength of electron impact on Lilike C with the configuration interaction wavefunctions, in which the configuration inte ractions of an innershell electron excitation are included. For transition 1s ２２s２S１s１２p２Po,the result in this paper is a litt le smaller than that of the close coupling approximation and a little larger than that of CoulombBornexchange approximation，and accords with that of the experiment except that nearer excita tion threshold.
1999,
11.
Abstract:
The microwave property of highTc superconductive reson ator,espec ially the surface resistance and the magnetic field penetration depth were discussed. The value of them were measured and the relationship between surface resistance and temperature was also studied. The microwave system utilizes a parallel plat e highTc superconductive resonator consisted of YBa2Cu3O7 films and sapphire layer inside．
The microwave property of highTc superconductive reson ator,espec ially the surface resistance and the magnetic field penetration depth were discussed. The value of them were measured and the relationship between surface resistance and temperature was also studied. The microwave system utilizes a parallel plat e highTc superconductive resonator consisted of YBa2Cu3O7 films and sapphire layer inside．
1999,
11.
Abstract:
The array calorimeter detector was used to measure the uniformity of intensity distribution and output energy for large diameter(φ267mm) and high energy (400J)KrF laser beam. With a decrease of the diode voltage,the distribution becomes worse to have a saddle pattern. The optimum operation voltage of diode are of 580 to 600kV ．
The array calorimeter detector was used to measure the uniformity of intensity distribution and output energy for large diameter(φ267mm) and high energy (400J)KrF laser beam. With a decrease of the diode voltage,the distribution becomes worse to have a saddle pattern. The optimum operation voltage of diode are of 580 to 600kV ．
1999,
11.
Abstract:
The formula of COIL sign gain is derived approximately under the saturation conditions, in case that particles o ccupying the hyperfine sublevels of each electric level are at thermal equilibri um. The rule that the COIL central transition frequencies change with the iodine density is also achieved by using this formula. Related analysis results and discussion are given.
The formula of COIL sign gain is derived approximately under the saturation conditions, in case that particles o ccupying the hyperfine sublevels of each electric level are at thermal equilibri um. The rule that the COIL central transition frequencies change with the iodine density is also achieved by using this formula. Related analysis results and discussion are given.
1999,
11.
Abstract:
This paper provides theoretical model and calculated results of explo ding foil opening switch with three kinds of powerconditioning circuit such as mode F, or mode FT, or mode TF. Based on analyses of these circuit performances it is of more wide applied prospect for the mode TF circuit with the exploding foil opening switch．
This paper provides theoretical model and calculated results of explo ding foil opening switch with three kinds of powerconditioning circuit such as mode F, or mode FT, or mode TF. Based on analyses of these circuit performances it is of more wide applied prospect for the mode TF circuit with the exploding foil opening switch．
1999,
11.
Abstract:
By means of the FDTD method, we have carried out the modeling of burnout of the semiconductor devices under the Elec tromagnetic Pulse (EMP) environment. We obtained the transient behavior of pn ju nction device which is under the attack of rapidrise (about ns risetime ) EM P, and the variances of device parameters during the burnout of the device wh ich is caused by current through the device.
By means of the FDTD method, we have carried out the modeling of burnout of the semiconductor devices under the Elec tromagnetic Pulse (EMP) environment. We obtained the transient behavior of pn ju nction device which is under the attack of rapidrise (about ns risetime ) EM P, and the variances of device parameters during the burnout of the device wh ich is caused by current through the device.
1999,
11.
Abstract:
Electric fields radiated by ESD are studied experimentally with a mono pole antenna. Experiments showed that fields radiated by ESD are narrow pulses in time domain, and the fields can reach several kilovolts per meter when the discharge occurred at a few centimete rs from the unit under test. The frequency range of the fields is severaltens megahertz to several hun dreds megahertz．
Electric fields radiated by ESD are studied experimentally with a mono pole antenna. Experiments showed that fields radiated by ESD are narrow pulses in time domain, and the fields can reach several kilovolts per meter when the discharge occurred at a few centimete rs from the unit under test. The frequency range of the fields is severaltens megahertz to several hun dreds megahertz．
1999,
11.
Abstract:
A small passive electro optic EMP sensor over frequency range from 10kHz to 700MHz has been developed. The sensor's operation properties,such as the frequency response, li near dynamic range, sensitivity, optical power dependence, dipole element length dependence and impulse response ，were measured, which agreed with the calculated results. It has the characteristics of wideband, passive, small size and being free from electromagnetic interference, and can be used for EMP measurement in small volum e．
A small passive electro optic EMP sensor over frequency range from 10kHz to 700MHz has been developed. The sensor's operation properties,such as the frequency response, li near dynamic range, sensitivity, optical power dependence, dipole element length dependence and impulse response ，were measured, which agreed with the calculated results. It has the characteristics of wideband, passive, small size and being free from electromagnetic interference, and can be used for EMP measurement in small volum e．
1999,
11.
Abstract:
This paper describes the design and c onstruction of the axially insulated largearea diodes used in the 揌eaven1 ? The four axially insulated largearea diodes are connected to the 10 ohm pu lse transmission lines via the vacuum feed through tubes. The experimental resul ts with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm2 with a pulse width of 220 ns.The electron beams with a total energy of 25 kJ are obtained.
This paper describes the design and c onstruction of the axially insulated largearea diodes used in the 揌eaven1 ? The four axially insulated largearea diodes are connected to the 10 ohm pu lse transmission lines via the vacuum feed through tubes. The experimental resul ts with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm2 with a pulse width of 220 ns.The electron beams with a total energy of 25 kJ are obtained.
1999,
11.
Abstract:
A low jitter threeelectrode gas spark gap is studied. One of the important characteristics of the thre eelectrode gas spark gap is stability,which depends on gas type, pressure, electrode shape and material.With investigation, N２ is chosen, geometry of triggerelectrode is designed as diamond，mainelectrode and triggerelectr ode material is brass.Experimental results confirm the validity of the methode . Switch jitter which is less than 2ns has been achieved.
A low jitter threeelectrode gas spark gap is studied. One of the important characteristics of the thre eelectrode gas spark gap is stability,which depends on gas type, pressure, electrode shape and material.With investigation, N２ is chosen, geometry of triggerelectrode is designed as diamond，mainelectrode and triggerelectr ode material is brass.Experimental results confirm the validity of the methode . Switch jitter which is less than 2ns has been achieved.
1999,
11.
Abstract:
One dimensional multigroup radiation transport program (RDMG) is use d to simulate the process of Xray heating Au disk. It is found that although the outward spectrum from Au disk is near Planckian,the peak region is in some way deviated from Planck spectrum. This is due to the fact that the corona plasm a is optical thin to the frequencies of peak region ,which is corresponding to the valley of the absorption coefficient spectrum between the peak of N band and that of O band．
One dimensional multigroup radiation transport program (RDMG) is use d to simulate the process of Xray heating Au disk. It is found that although the outward spectrum from Au disk is near Planckian,the peak region is in some way deviated from Planck spectrum. This is due to the fact that the corona plasm a is optical thin to the frequencies of peak region ,which is corresponding to the valley of the absorption coefficient spectrum between the peak of N band and that of O band．
1999,
11.
Abstract:
The plasma condition and the ga in coef ficient of a carbon fibertarget,which is irradiated by obliqueincident laser light were calculated. The refraction of laser and the resonance absorption of Ppolarization laser were considered. The gain coefficient value of Hlike C, n=2,3 comparing with verticalincident is higher,however the gain regio n becomes narrower and the gian region towards to the outer layer of the fiber target plasma.
The plasma condition and the ga in coef ficient of a carbon fibertarget,which is irradiated by obliqueincident laser light were calculated. The refraction of laser and the resonance absorption of Ppolarization laser were considered. The gain coefficient value of Hlike C, n=2,3 comparing with verticalincident is higher,however the gain regio n becomes narrower and the gian region towards to the outer layer of the fiber target plasma.
1999,
11.
Abstract:
The prepulse voltage of the FlashＩ and its reduction ar e analysed. The prepulse voltage between the cathode and the anode has been measured with the capacitive voltage detector, and a new improved equivalent circuit model is proposed. The important effect of direct capacity coupling betw een the intermediate cylinder and the end of diode is pointed out. The prepulse voltage simulated with this model come s closer to the measured result. The scheme of reducing prepulse voltage further is designed．
The prepulse voltage of the FlashＩ and its reduction ar e analysed. The prepulse voltage between the cathode and the anode has been measured with the capacitive voltage detector, and a new improved equivalent circuit model is proposed. The important effect of direct capacity coupling betw een the intermediate cylinder and the end of diode is pointed out. The prepulse voltage simulated with this model come s closer to the measured result. The scheme of reducing prepulse voltage further is designed．
1999,
11.
Abstract:
The double anode electron gun is designed and calculated according to the requirements for the gyrotrons.The electrode shapes, electron trajectory and electron beam parameters are also given.The electron gun has such characteristics as small velocity spread , good laminar flow and small volume, etc.
The double anode electron gun is designed and calculated according to the requirements for the gyrotrons.The electrode shapes, electron trajectory and electron beam parameters are also given.The electron gun has such characteristics as small velocity spread , good laminar flow and small volume, etc.
