共查询到20条相似文献,搜索用时 781 毫秒
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A new and simple type of electron gun is presented.Unlike conventional electron guns,which require a heated filament or extractor,accelerator and focusing electrodes,this gun uses the collimated electron microchannels of an inertial electrostatic confinement(IEC) discharge to achieve the same outcome.A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge.Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode.This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid.The internal operating pressure range of the gun is 35-190 m Torr.A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential.The chamber was operated at pressures of 4-12 m Torr.The measured current produced by the gun was 0.1-3 m A(0.2-14 m A corrected measurement) for discharge currents of 1-45 m A and discharge voltages of 0.5-12 k V.The collimated electron beam emerges from the aperture into the vacuum chamber.The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun.This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required. 相似文献
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Previous electrostatic particle-in-cell (PIC) simulations have pointed out that electron phase-space holes (electron holes) can be formed during the nonlinear evolution of the electron two-stream instability. The parallel cuts of the parallel and perpendicular electric field have bipolar and unipolar structures in these electron holes, respectively. In this study, two-dimensional (2D) electromagnetic PIC simulations are performed in the x y plane to investigate the evolution of the electron two-stream instability, with the emphasis on the magnetic structures associated with these electron holes in different plasma conditions. In the simulations, the background magnetic field (Bo= Boex ) is along the x direction. In weakly magnetized plasma (Ωe < ωpe , whereΩe and ωpe are the electron gyrofrequency and electron plasma frequency, respectively), several 2D electron holes are formed. In these 2D electron holes, the parallel cut of the fluctuating magnetic field δBx and δBz has unipolar structures, while the fluctuating magnetic field δB y has bipolar structures. In strongly magnetized plasma (Ωe > ωpe ), several quasi-1D electron holes are formed. The electrostatic whistler waves with streaked structures of E y are excited. The fluctuating magnetic field δB x and δBz also have streaked structures. The fluctuating magnetic field δBx and δB y are produced by the current in the z direction due to the electric field drift of the trapped electrons, while the fluctuating magnetic field δBz can be explained by the Lorentz transformation of a moving quasielectrostatic structure. The influences of the initial temperature anisotropy on the magnetic structures of the electron holes are also analyzed. The electromagnetic whistler waves are found to be excited in weakly magnetized plasma. However, they do not have any significant effects on the electrostatic structures of the electron holes. 相似文献
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Electron acoustic solitons in collisionless and weakly relativistic plasmas are studied. The Krylov–Bogoliubov–Mitropolsky perturbative technique is employed to obtain the nonlinear Schrodinger wave equation. We have numerically investigated modulational instability for different values of the streaming velocity. Graphs have been plotted to see the change in amplitude and inverse width by varying different plasma parameters. 相似文献
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本文介绍了一种应用于多能量档电子直线加速器栅控电子枪的专用电源。根据栅控电子枪的工作需求,电子枪的阴极处于-50 kV高压上,电源的3路输出,包括灯丝电源、偏压电源和栅控脉冲电源,均通过高压隔离变压器,将信号输送到高压端的灯丝、阴极和栅极上。利用主控计算机精确调节了电子枪发射束流的大小和脉冲宽度,以满足加速器多能量输出的需求。高压端均为无源器件,以降低故障率。此电源结构简单、调节方便、工作稳定,已在多能量档电子直线加速器上连续工作近4 a,运行状态良好。 相似文献
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Cross section measurements are reported for electron capture into the 3s state by 20-150 keV protons and deuterons incident on molecular hydrogen and deuterium. Conventional wisdom indicates that these cross sections should be nearly identical at equivalent velocities and researchers routinely use deuteron projectiles to extend proton excitation curves downward in velocity. This practice has been questioned on theoretical grounds and some investigators have reported consistent differences in cross sections for the two isotopes, however, nearly always within the experimental uncertainty of the measurements. We have made a systematic study of the 3s electron capture cross sections described above to check for isotopic effects. These cross sections are then compared to previous measurements reported in the literature. 相似文献
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Tove P. A. Berg S. Andersson L. P. Ericsson B. Norde H. 《IEEE transactions on nuclear science》1972,19(3):85-94
A review is given of the properties of parallel plate electron multipliers and present development work is described. In particular the type of multiplier fabricated by RF-sputtering of separate potential divider and secondary emission layers is discussed. This allows optimization of the two functions. Typical plate dimensions are 2O×2O mm, with a separation of ? 0.3 mm. The theories for the straight pipe-shaped multiplier and the parallel plate multipliers are discussed and a comparison is made with measurements, The influence of the geometry is discussed, including optimum plate spacing. A difference compared with tubular multipliers is that electron avalanches spread sideways, because of statistics and electric repulsion effects. Studies of pulse shapes and timing properties are reported. Current pulses at the oultput are about 10 nsec long, for each electron avalanche, Severlal superimposed avalanches caused by ionic feedback build up the integrated voltage pulse to a length of a few tenths of a ?sec. 相似文献
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Wide-aperture low-energy electron accelerators, which provide simultaneous irradiation of large surfaces and volumes, are used in radiation technology, ionization setups for gas lasers, and in scientific research. Certain modifications of wide-aperture electron accelerators – ionization setups for CO and CO2 lasers and ozone generator based on an electron-beam-controlled discharge – are described. 相似文献
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Prticle-in-cell(PIC) simulations demonstrated that,when the relativistic magnetron with diffraction output(MDO) is applied with a 410 kV voltage pulse,or when the relativistic magnetron with radial output is applied with a 350 kV voltage pulse,electrons emitted from the cathode with high energy will strike the anode block wall.The emitted secondary electrons and backscattered electrons affect the interaction between electrons and RF fields induced by the operating modes,which decreases the output power in the radial output relativistic magnetron by about 15%(10%for the axial output relativistic magnetron),decreases the anode current by about 5%(5%for the axial output relativistic magnetron),and leads to a decrease of electronic efficiency by 8%(6%for the axial output relativistic magnetron).The peak value of the current formed by secondary and backscattered current equals nearly half of the amplitude of the anode current,which may help the growth of parasitic modes when the applied magnetic field is near the critical magnetic field separating neighboring modes.Thus,mode competition becomes more serious. 相似文献
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A. Patran D. Stoenescu R. S. Rawat S. V. Springham T. L. Tan L. C. Tan M. S. Rafique P. Lee S. Lee 《Journal of Fusion Energy》2006,25(1-2):57-66
The paper describes the construction of a magnetic electron analyzer for pulsed beam electron energy distribution studies. The single shot information is obtained using a NMOS linear image sensor. Both the energetical and the sensitivity calibration were performed using careful numerical simulations. For simplicity, the signals can be read on an oscilloscope, and they are transmitted via an optic fiber, which allows the analyzer to work while connected to high voltage. The analyzer was successfully implemented on a 15 kV/3 kJ plasma focus device and was used to study the electron energy distribution in the 30–660 keV range.. 相似文献
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本文简要介绍了电子辐射加工技术的主要特点以及中国科学院高能物理研究所10MeV/15kW辐照加速器的主要性能。给出了能量、流强、扫描均匀性、扫描长度以及束斑形状等5个重要参数的测量方法及结果。 相似文献
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Udaybir Singh Anil Kumar Nitin Kumar Narendra Kumar Bhanu Pratap L.P. Purohit A.K. Sinha 《Fusion Engineering and Design》2012,87(9):1583-1588
This paper presents the numerical simulation of a double-beam magnetron injection gun (DB-MIG) and beam-wave interaction for 60 GHz, 500 kW gyrotron. The beam-wave interaction calculations, power and frequency growth estimation are performed by using PIC code MAGIC. The maximum output power of 510 kW at 41.5% efficiency, beam currents of 6 A and 12 A, electron beam velocity ratios of 1.41 and 1.25 and beam voltage of 69 kV are estimated. To obtain the design parameters, the DB-MIG with maximum transverse velocity spread less than 5% is designed. The computer simulations are performed by using the commercially available code EGUN and the in-house developed code MIGANS. The simulated results of DB-MIG design obtained by using the EGUN code are also validated with another trajectory code TRAK, which are in good agreement. 相似文献