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1.
The discharge characteristics and the parameters of the cathode plasma in a two-stage ion source with a grid plasma cathode and a magnetic trap in the anode region are investigated. It is shown that an increase in the gas pressure and the accompanying increase in the reverse ion current in the bipolar diode between the cathode and anode plasmas lead to an increase in the cathode plasma potential and a transition of the cathode into the regime of electron emission from the open plasma boundary. The dependence of the ion current extracted from the anode plasma on the area of the exit aperture of the hollow cathode and the mesh size of the grid plasma cathode is explained. The conditions at which the ion emission current from the anode plasma is maximum are determined. The potential difference at the bipolar diode is measured by using the probe method. It is shown that, when the gas pressures reaches a critical value determined by the mesh size of the grid plasma cathode, the discharge passes into a contracted operating mode, in which the ion current extracted from the anode plasma decreases severalfold. 相似文献
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M. B. Agranat N. E. Andreev S. I. Ashitkov A. V. Ovchinnikov D. S. Sitnikov V. E. Fortov A. P. Shevel’ko 《JETP Letters》2006,83(2):72-74
Characteristic K α x rays arising when a metallic target is irradiated by femtosecond infrared pulses that are generated by a terawatt chromium-forsterite laser system (1240 nm, 90 mJ, 80 fs) are studied. The absolute yield (up to 3 × 108 photons/sr pulse) and the coefficient of the transformation of laser radiation to K α radiation (maximum value ≈0.03%) are measured for an iron target. The dependence of the radiation intensity on the angle of incidence of p polarized laser radiation is analyzed. The mechanisms of the production of fast electrons responsible for generating characteristic x rays are discussed. 相似文献
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E. V. Parkevich I. N. Tilikin A. V. Agafonov T. A. Shelkovenko V. M. Romanova A. R. Mingaleev S. Yu. Savinov G. A. Mesyats S. A. Pikuz 《JETP Letters》2016,103(5):357-361
To study processes in a high-current vacuum diode with a cathode in the form of a single pin made of a metallic wire 20–30 μm in diameter, the method of high-resolution projection X-ray radiography with an X-pinch as a source has been used. A strong inhomogeneity of the energy contribution to the wire has been revealed. The smallest energy release has been observed near the end of the pin, where the electric field strength is maximal. Hard X rays, as well as the ejection of matter from the anode, have been observed, indicating the generation of an electron beam with the parameters characteristic of explosive electron emission in the diode with this configuration. The data obtained indicate complex processes occurring in the diode. Possible scenarios of their development have been considered. 相似文献
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A. E. Dubinov I. A. Efimova V. I. Kargin E. A. Ryaslov V. D. Selemir 《Technical Physics》2007,52(6):809-811
A soft X-ray generator is designed on the basis of a vircator the plasma anode of which is formed by electrical explosion of anode foil. The intensity of soft X-ray radiation (E γ > 20 eV) produced by vircators with a metal and plasma anode is measured. Microwave pulses indicating the presence of a virtual cathode in the plasma beam are detected. 相似文献
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V. F. Tarasenko S. K. Lyubutin S. N. Rukin B. G. Slovikovskii I. D. Kostyrya V. M. Orlovskii 《Technical Physics》2005,50(11):1462-1466
The subject of study is ultrashort avalanche-produced electron pulses generated in air under atmospheric pressure. The current
amplitude of the pulses behind 45-μm-thick AlBe foil exceeds 100 A, and their FWHM is ≈0.2 ns. The conditions of generation
of ultrashort pulses persist at repetition rates as high as 1.5 kHz. A volume discharge initiated in an open coaxial-electrode
gas diode by high-voltage nanosecond pulses generates hard (> 60 keV) radiation. 相似文献
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Ikhlef A. Skowronek M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(6):669-675
The X-ray emission from a source based on a small vacuum discharge is studied. Two different X-ray pulses whose intensities vary with the anode-cathode distance are identified. Time integrated pinhole images show that the whole anode and the teflon insulator emit X-rays. Some of the X-ray emission is found to originate also in the vicinity of the tungsten anode. The temporal behavior of the X-ray varies with respect to the distance between the anode and the cathode. Three different cathode geometries are tested: hollow cathode, hollow conical cathode, and massive or needle cathode. The spatial distribution of the X-ray sources is obtained by means of a sensitive imaging device. Some X-ray spots that appear in the discharge gap near the anode tip are similar to hot spots found in more powerful discharges 相似文献
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阳极杆箍缩二极管(RPD)具有小焦斑、高亮度的特点,是闪光X光机领域的研究热点。基于Marx发生器和脉冲形成线技术路线产生1 MV高电压脉冲驱动RPD,开展了不同结构参数二极管实验研究。基于RPD物理过程的数值模型,分析了结构参数对箍缩物理过程的影响。研究表明在1 MV电压下,RPD阴极等离子体平均扩散速度、阳极等离子体平均扩散速度分别为2,0.6 cm/μs时,该模型可以较好地描述实验结果。在阳极杆直径一定的情况下,二极管数值模型表明减小阴极孔径可以使二极管更快进入强箍缩状态,但过小的阴极孔径会导致二极管间隙过早闭合。 相似文献
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S. A. Sorokin 《Technical Physics》2011,56(7):957-962
Experimental data for creating an X-ray source several millimeters in size on the basis of a plasmafilled rod-pinch diode are reported. Experiments are carried out on the MIG high-current generator. A voltage pulse applied to the diode is sharpened and shortened by injecting plasma into the interelectrode gap up to the plasma-filled diode. Radiation extraction from the vacuum chamber in the paraxial direction is provided by inverting the positions of the cathode and anode using a post-hole vacuum convolute. It is demonstrated that the energy of a low-impedance high-current generator can be deposited with a high efficiency into an electron beam focused on the 1-mm2 tip of the rod-shaped anode. With a tapered tungsten rod 1.5 mm in diameter used as an anode, a pulsed X-ray source about 1 mm in size generating 30-ns-long pulses is obtained. The absorbed dose per pulse measured with a LiF thermoluminescent dosimeter behind a 5-mm-thick aluminum screen 1 m away from the source reaches 0.042 Gy. 相似文献
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E. H. Baksht A. G. Burachenko A. V. Kozyrev I. D. Kostyrya M. I. Lomaev V. K. Petin D. V. Rybka V. F. Tarasenko S. V. Shljakhtun 《Technical Physics》2009,54(1):47-55
The spectra of electrons and X-ray photons generated in nanosecond discharges in air under atmospheric pressure are investigated
theoretically and experimentally. Data for the discharge formation dynamics in a nonuniform electric field are gathered. It
is confirmed that voltage pulses with an amplitude of more than 100 kV and a rise time of 1 ns or less causing breakdown of
an electrode gap with a small-radius cathode generate runaway electrons, which can be divided into three groups in energy
(their energy varies from several kiloelectronvolts to several hundreds of kiloelectronvolts). It is also borne out that the
formation of the space charge is due to electrons appearing in the gap at the cathode and a major contribution to the electron
beam behind the foil comes from electrons of the second group, the maximal energy of which roughly corresponds to the voltage
across the gap during electron beam generation. X-ray radiation from the gas-filled diode results from beam electron slowdown
both in the anode and in the gap. It is shown that the amount of group-3 electrons with an energy above the energy gained
by runaway electrons (in the absence of losses) at a maximal voltage across the gap is much smaller than the amount of group-2
electrons. 相似文献
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The generation of a 250-μs-wide electron beam in a plasma-emitter diode is studied experimentally. A plasma was produced by a pulsed arc discharge in hydrogen. The electron beam is extracted from a circular emission hole 3.8 mm in diameter under open plasma boundary conditions. The beam accelerated in the diode gap enters into a drift space in the absence of an external magnetic field through a hole 4.1 mm in diameter made in the anode. The influence of electron current deposition at the edge of the anode hole on the beam’s maximum attainable current, above which the diode gap breaks down, is studied for different accelerating voltages and diode gaps. The role of processes occurring on the surface of the electrodes is shown. For an accelerating voltage of 32 kV, a mean emission current density of 130 A/cm2 is achieved. The respective mean strength of the electric field in the acceleration gap is 140 kV/cm. Using the POISSON-2 software package, the numerical simulation of the diode performance is carried out and the shape of steady plasma emission boundaries in the cathode and anode holes is calculated. The influence of the density of the ion current from the anode plasma surface on the maximum attainable current of the electron beam is demonstrated. 相似文献
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E. H. Baksht M. I. Lomaev D. V. Rybka D. A. Sorokin V. F. Tarasenko 《Technical Physics》2008,53(12):1560-1564
The parameters of an electron beam generated in helium in the pressure range p = 10−4−12 atm are studied. Nanosecond high-voltage pulses are applied to a gap between a tubular cathode and planar anode, which
is made of 45-μm-thick AlBe foil. Behind the anode, an electron beam is detected at a helium pressure of 12 atm. The pressure
dependence of the beam current amplitude shows three peaks at p ≈ 0.01, ≈ 0.07, and ≈ 3 atm. The beam-induced glow of a luminescent film placed behind the foil and the discharge glow at
different helium pressures in the gas-filled diode are photographed. 相似文献
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Three Dimensional Angular Distributions of X‐Rays in a 4 kJ Plasma Focus Device for Different Anode Tips Using TLD‐100 Dosimeters 下载免费PDF全文
Time and energy integrated measurements of the 3‐D angular distribution of X‐rays emission within the chamber of a 4 kJ Mather‐type plasma focus is investigated employing four different anode shapes and using nitrogen as the filling gas by the TLD‐100 thermoluminescence dosimeters. The distributions of X‐ray radiation in the energy range of 5 keV to several hundred keV were bimodal for all of the anode tips, peaked approximately at ±15°. The intensity of X‐rays decreased abruptly along the central axis of the device where the quasi cylindrical plasma pinch was formed. High intensity of X‐ray was observed in the case of a tapered ?at‐end anode, whereas less was obtained with the cylindrical hollow‐end anode. The maximum nitrogen X‐rays were for the tapered flat‐end anode at 4.5 mbar and 13 kV. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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本文基于人体放电模型分别对肖特基势垒二极管的阴极和阳极进行同一电压脉冲下的多次放电, 利用热电子发射理论、1/f噪声的迁移率涨落模型和白噪声理论, 分别深入研究静电放电损伤对器件I-V和低频噪声的影响. 结果表明, 静电放电作用于肖特基二极管阴极时损伤更严重, 噪声参量变化率更大. 随着放电次数的增加, 正向特性无变化, 反向电流总体增大, 偶有减小; 而正向和反向 1/f噪声均增大. 鉴于噪声与应力条件下器件内部产生的缺陷与损伤有关, 且更敏感, 故可将低频噪声特性用作肖特基二极管的静电放电损伤灵敏表征工具. 相似文献
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Akashi H. Sakai Y. Takahashi N. Sasaki T. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(1):8-9
Dynamics of a filament discharge in a discharge-excited XeCl excimer laser medium has been simulated for a sequence of discharge pulses (shots). In the present model a filament discharge is triggered at a microprotrusion on a cathode surface. After the first discharge initiation, a hot spot is created near the cathode, then filament develops toward the anode in the second shot. Images of the filament discharge development and its properties in a XeCl excimer laser are presented 相似文献
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Streak photographs of the axial motion of vapourized anode and cathode materials in a flash X-ray (FXR) discharge correlated with the time derivative of the discharge current (dI/dt) indicate that clouds of vapourized metal are formed outside the electrode surfaces during the first significantdI/dt dip, i.e. during the pinching of the discharge column. The anode cloud propagates towards the cathode with a velocity of (1–1.5)×106 cm/sec and reaches the cathode cloud at current zero. This means that the discharge current is not entirely carried by a metallic arc until after the first current zero. The metal vapour propagation is discussed in relation to existing theories. 相似文献
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V. I. Gushenets N. N. Koval’ V. S. Tolkachev P. M. Shchanin 《Technical Physics》1999,44(11):1318-1321
The emission properties of a plasma cathode based on a nanosecond pulsed glow discharge with currents of up to 200A at a pressure
of 5×10−2 Pa are studied experimentally. Stable ignition and burning of the discharge are ensured if the current in the auxiliary pulsed
discharge is 25–30% of that in the main discharge and its pulse duration exceeds that of the main discharge by more than an
order of magnitude. Emission current pulses from the cathode with amplitudes of up to 140A fully reproduce the discharge current
and are determined by the transparency of the grid anode.
Zh. Tekh. Fiz. 69, 62–65 (November 1999) 相似文献
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Chee Mang Ng Siew Pheng Moo Chiow San Wong 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(4):1146-1153
The variation of the soft X-ray emission in a low energy (3 kJ, 15 kV) plasma focus over a range of pressures is investigated. The working gases are argon and an argon-hydrogen mixture. The X rays are detected using an assembly of PIN-Si diodes with differential filtering and with a multipinhole camera, soft X rays originating from the plasma and from electron beam activity on the copper anode are observed. In general, three pressure regimes can be discerned. In the first regime, both the plasma X rays and the copper line radiation are weak. In the second regime, the X-ray emission is intense and the contribution from copper lines is strong. In the third pressure regime, the plasma X rays are intense while contribution from the copper X-rays are weak 相似文献