共查询到20条相似文献,搜索用时 15 毫秒
1.
Arita H. Suzuki K. Kurosawa Y. Hirasawa K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(4):695-698
Soft X-ray emissions by Z -pinch discharge between vacuum spark electrodes are examined. Mainly aluminum and molybdenum were utilized to generate soft X-rays, and emissions resulted for pulse currents of about 150 kA. These emissions increased as the discharge current increased. A large X-ray intensity was obtained when a spherical anode and a conical cathode were used. A stable spot plasma was produced for an electrode separation distance of 2 mm. For molybdenum, the X-ray emission of the 0.52-nm line and continuous X-rays of 0.65-1.2 nm were observed. The X-ray continuum was assumed to be a recombination continuum. For aluminum alloy containing magnesium, the 0.62-, 0.66-, 0.72-, 0.78-, and 0.92-nm lines were observed. The experimental results indicate that vacuum spark is a potential exposure source for X-ray lithography 相似文献
2.
A model of the unstable stage of a spark discharge in vacuum is proposed, which describes all typical manifestations of this
stage, including current spikes in the diode, an increase in the potential at the cathode flame front, collective acceleration
of ions in vacuum and plasma diodes, change in the cathode erosion mechanism, and the emergence of electron microbeams with
a high current density at the anode. It is shown that these processes are associated with the formation of a charged electron
layer of a spatially inhomogeneous plasma at the cathode flame boundary at the unstable stage of the spark discharge in vacuum.
The emergence of this layer is associated with a limited emissive ability of the plasma at the cathode flame front during
its expansion in vacuum. This leads to disruption of the plasma (field-induced emission of electron from the boundary region
of the flame) and the formation of a short-lived charged plasma, viz., high-density ion cluster at the cathode flame boundary.
The estimates obtained using this model are in good agreement with the experimental data on physical processes at the unstable
stage of a vacuum spark discharge. 相似文献
3.
Wong C.S. Ong C.S. Lee S. Choi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(4):405-409
The generation of prebreakdown electron beams in a low-energy vacuum spark with a hollow-cathode configuration is observed under a range of experimental conditions. The vacuum spark studied is powered by either a 25-kV, 3.3-nF single capacitor discharge or a two-stage, 50-kV, 1.65-nF Marx. The electron beams are detected by observing the X-ray emission from the anode tip produced by electron impact. Results show that an electron beam is formed well before the onset of the electrical breakdown. This prebreakdown electron beam has an initial slow buildup phase followed by an exponential rise, leading to the breakdown of the discharge. This behavior of the electron beam evolution is in good qualitative agreement with the model simulation of the pseudospark phenomenon obtained for a transient hollow-cathode discharge 相似文献
4.
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
5.
《Physics letters. A》1986,116(2):49-53
The paper presents the results of space- and time-resolved studies of X-rays and neutrons emitted by the SOWA-150A ion-impulsion facility equipped with a coaxial set multi-rod electrodes. Proportionality and correlation of neutron and hard X-ray pulses favour the hypothesis of a beam-target mechanism of the neutron production. 相似文献
6.
An inexpensive and simple demountable X-ray source, having facilities to excite X-rays either by bombardment of a target by
electrons or by fluorescence, has been developed using a stainless steel chamber having six ports. A cathode assembly from
a burnt out sealed off Machlett X-ray tube was carefully removed and reused in the present set-up after replacing the filament.
A conventional vacuum system consisting of a rotary and diffusion pumps has been utilized for evacuating the chamber. The
set-up can be conveniently utilized to carry out X-ray emission spectroscopic work. 相似文献
7.
In this work, the continuum spectrum of X-rays originated from the interaction of a moderate intensity ns Nd:YAG laser (1064 nm, 9 ns, 30 Hz, 900 mJ, 1011 W/cm2) with Ta target producing plasma is investigated. Plasma expands unisotropically with a velocity, depending on the pressure of the residual gas in the vacuum chamber. The X-ray intensity is a function of the laser energy and of the gas pressure inside the chamber. The X-ray energy is measured with an X-ray filter positioned in front of the Si(Li) solid-state detector. A temperature of about ~1–2 keV of the hot electrons, responsible for the continuum spectrum emission from the plasma, is calculated from the fit of the X-ray spectrum, applying a Maxwellian distribution. 相似文献
8.
Chiow San Wong Chia Xian Ong Siew Pheng Moo Choi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):265-269
The discharge characteristics of a vacuum spark triggered by the transient hollow cathode discharge (THCD) electron beam is investigated over a wide variety of discharge conditions. Two systems of the vacuum spark device have been considered-the first system powered by eight 2700-pF doorknob capacitors charged to a voltage of 40 kV (input energy of 17.6 J); while the second system employs a single 1.85-μF Maxwell capacitor discharged at a voltage of 20 kV (input energy of 370 J). The operating pressure of these systems has been varied over the range of 10 -2 to 10-5 mbar in order to examine the effect of the operating pressure on the plasma formation of the vacuum spark discharge. The effectiveness of plasma heating has been found to be significantly enhanced in the two vacuum spark systems studied here. In particular, the plasma of the 17.6 J system has been observed to be heated to a condition hot enough to emit in the X-ray region when the operating pressure is reduced from 10-2 to 10-5 mbar. Similarly, in the case of the 370 J system, hot spot formation is also observed to occur only at a low operating pressure of 10-4 mbar 相似文献
9.
Hamid Latif M. Shahid Rafique M. Khaleeq-ur-Rahaman Abdul Sattar S. Anjum A. Usman 《辐射效应与固体损伤》2013,168(11):942-953
Laser-induced plasma is used as an X-ray source for the growth of hillocks like nanostructures on platinum surface. To generate X-rays, plasma is produced by Nd:YAG laser, which is operated at second harmonics (λ?=?532?nm, E?=?400?mJ). Analytical grade 5?N pure Al, Cu and W are used as laser targets for X-rays production. X-rays produced from Al, Cu and W plasmas are used to irradiate three analytical grade (5?N pure) platinum substrates, respectively, under the vacuum ~10?4 torr. XRD analysis shows considerable structural changes in the exposed platinum. The decrement in reflection intensities, increment in dislocation line density, change in d-spacing and disturbance in the periodicity of planes evidently prove these structural changes. Atomic force microscope AFM topographic analysis of the platinum exposed to X-rays emitted from Al, Cu and W targets showed that nanometer-size hillocks are produced on the platinum surface irrespective of the source. It has also been observed that due to these hillocks, the roughness of the surface has increased. Conductivity of hillocks produced from X-rays produced by Al, Cu and W targets is compared and it is shown that the hillocks produced by Al target X-rays have better conductivity compared to the hillocks produced by X-rays from Cu and W targets. 相似文献
10.
Yerbolat A. Ussenov Moldir T. Toktamyssova Merlan K. Dosbolayev Maratbek T. Gabdullin Talgat T. Daniyarov Tlekkabul S. Ramazanov 《等离子体物理论文集》2021,61(3):e202000140
This study demonstrates a method for the deposition of CuOx thin films by combining atmospheric pressure plasma jet with spark discharge. In this type of discharge source, the bulk copper material of spark discharge electrodes plays the role of a precursor. Copper atoms and particles go through the physical processes of sputtering, evaporation, and further agglomeration and condensation in the plasma jet and on the substrate. The experiments were carried out with and without a combination of discharges. The material coated on the substrate was studied using a scanning electron microscope, Raman spectroscopy, and energy-dispersive X-ray spectroscopy. The characteristics of the set-up and plasma, such as I-V curves, optical emission spectra, and substrate temperature, were also measured. Copper electrodes were examined for erosion by a scanning electron microscope. The results demonstrate that deposits coated by combined discharge show denser and thicker films. 相似文献
11.
Chuaqui H. Favre M. Saavedra R. Wyndham E.S. Soto L. Choi P. Dumitrescu-Zoita C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(4):1162-1167
The behavior of a medium energy (~1 kJ) pulse-power-driven vacuum spark is shown to depend on the electrode material and form of the anode in otherwise similar conditions of operation. The dynamical evolution of the discharge is followed from its soft X-ray emission. The electrode materials compared are titanium and aluminum with a form of anode that is tubular or conical. The use of a tubular anode favors a more uniform sheath and a better formation of a dense Z-pinch and the ensuing hot spots are found to be at least twice as bright. The position of the brightest spots differs according to the material and the electrode shape, and is found to coincide with the shape of the sheath. The energy output is measured and the density of the plasma in the hot spots may be calculated 相似文献
12.
Combination of spark discharge and nanoparticle-enhanced laser-induced plasma spectroscopy
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Qing-Xue Li 《中国物理 B》2022,31(8):85201-085201
A combination of spark discharge and nanoparticle-enhanced laser-induced plasma spectroscopy is investigated. Depositing Au nanoparticles at the surface of a brass target can enhance the coupling of the target and the laser. More atoms in the brass sample are excited. As a secondary excitation source, spark discharge reheats the generated plasma, which further amplifies the enhancement results of nanoparticles. The spectral intensity with the spark discharge increases more obviously with nanoparticle concentration increasing than without the spark discharge. Also, plasma temperature and electron density are calculated by the Boltzmann plot and Stark broadening. The changes in the plasma temperature and electron density are consistent with the spectral emission changes. 相似文献
13.
针对SILEX钛宝石激光器参数,采用PIC数值模拟程序VORPAL对激光尾波场加速进行了模拟,得到了电子轨迹及能量数据,进而通过理论计算得到了空泡机制下X射线辐射特性。结果表明,空泡机制下高能电子在空泡中做betatron振荡且多数电子被加速到170 MeV左右;加速能量较低的电子(约100 MeV), 其辐射谱为临界能量约3 keV的类同步辐射谱,发散角约为8 mrad,而能量较高的电子(约170 MeV)对应的光子临界能量约为10 keV。 相似文献
14.
15.
The sliding spark plasma – which is produced via ablation of a dielectric material enforced between a pair of electrodes by a pulsed high-voltage discharge propagating along the dielectric surface – has immense potential as a simple but novel spectroscopic source for direct in situ quantitative analysis of non-conducting samples, a ubiquitous theme in material characterization. The plasma-excited optical spectrum spans a broad spectral range Vacuum Ultra Violet-Near Infra Red (VUV-NIR) and carries the atomic and molecular signatures of the base matrix chemical composition. Since the analytical figures of merit for quantitative spectroanalysis are a function of the spark source and dielectric matrix ablation characteristics, we systematically studied the sliding spark plasma source, utilizing a charge-coupled device spectrometer with blazed holographic grating in order to find the combination of parameters that can tailor the source for trace spectroanalysis of dielectrics in air and atmospheric pressure. It was observed that in the UV–vis spectral range a unique set of sample matrix conditions, besides spark source parameters, exists for enhanced trace analyte spectral emission with low signal-to-noise ratios and where trace spectrochemical analysis of dielectrics depends multivariately on spark scan frequency, electrode geometry, plasma discharge current, spark source inductance, initial rate of applied voltage, mode of sample ablation, and specific capacitance of the dielectric surface. 相似文献
16.
O. A. Bashutin I. G. Grigoryeva V. A. Kostyushin A. S. Savelov G. Kh. Salakhutdinov 《Physics of Atomic Nuclei》2019,82(10):1400-1403
The spectral composition and X-ray radiation yield of a micropinch discharge plasma obtained at a facility of the low-inductance vacuum spark type are studied as a function of the polarity and design of the electrodes of the discharge system. It is shown that the X-ray radiation of the micropinch discharge plasma depends on the configuration of the electric field in the interval between the discharge electrodes, which determines the amount of erosion products involved in the micropinch process, resulting in the increase in the plasma density and its radiative characteristics. 相似文献
17.
The Jülich DPF I machine was modified to operate as a vacuum spark. It was established that with an operating pressure varying from 10-4 to 10-5 torr a voltage within the range of 14–17 kV was necessary to ensure a dense plasma phase as indicated by soft X-ray pinhole photography and current measurements. Operating with a LiD-filled channel in the anode, occasional bursts of neutrons were detected with a time-of-flight scintillator system. The yield, however, was erratic and below 107 per discharge. 相似文献
18.
19.
三电极气体火花开关带有触发极,相比两电极开关,其开关导通的可控性较高,工作电压较低且抖动小,所以气体火花开关中三电极开关的应用较为广泛.本文针对大气压氮气环境下的两电极开关和三电极开关的击穿机制进行了理论与数值模拟研究.通过理论和数值计算发现,对于平板-平板的两电极开关来说,低电压下(小于6.3 kV)无法产生流注击穿,高电压下(大于6.3 kV)会先形成由阴极到阳极的负流注,然后再形成由阳极向阴极的正流注.而在三电极开关的击穿过程中,首先会在触发极和绝缘体之间发生击穿,然后这个通道不断向阴阳极扩展,最终形成阴阳极之间的电弧通道.在本文的计算工况下,如果需要阴极-触发极、阳极-触发极同时击穿的话,其阴极-触发极之间的外加电压需要大于1.18 kV,而阳极-触发极之间的外加电压需要大于3 kV.当考虑触发极的场致发射后,该击穿阈值可以显著降低. 相似文献
20.
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