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气体放电中纳秒脉冲波形的实验研究 总被引:1,自引:0,他引:1
在利用示波器测试交流电弧发生器的一级放电回路的振荡波形时,在主振荡波形中观测到纳秒脉冲振荡波形.针对纳秒脉冲振荡波形进行了实验研究和初步的理论分析,所采用的实验方法能够为气体放电的纳秒脉冲研究提供一种新的实验依据. 相似文献
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Wind tunnel experiments on flow separation control of an Unmanned Air Vehicle by nanosecond discharge plasma aerodynamic actuation 下载免费PDF全文
Plasma flow control(PFC) is a new kind of active flow control technology, which can improve the aerodynamic performances of aircrafts remarkably. The flow separation control of an unmanned air vehicle(UAV) by nanosecond discharge plasma aerodynamic actuation(NDPAA) is investigated experimentally in this paper. Experimental results show that the applied voltages for both the nanosecond discharge and the millisecond discharge are nearly the same, but the current for nanosecond discharge(30 A) is much bigger than that for millisecond discharge(0.1 A). The flow field induced by the NDPAA is similar to a shock wave upward, and has a maximal velocity of less than 0.5 m/s. Fast heating effect for nanosecond discharge induces shock waves in the quiescent air. The lasting time of the shock waves is about 80 μs and its spread velocity is nearly 380 m/s. By using the NDPAA, the flow separation on the suction side of the UAV can be totally suppressed and the critical stall angle of attack increases from 20° to 27° with a maximal lift coefficient increment of 11.24%. The flow separation can be suppressed when the discharge voltage is larger than the threshold value, and the optimum operation frequency for the NDPAA is the one which makes the Strouhal number equal one. The NDPAA is more effective than the millisecond discharge plasma aerodynamic actuation(MDPAA) in boundary layer flow control. The main mechanism for nanosecond discharge is shock effect. Shock effect is more effective in flow control than momentum effect in high speed flow control. 相似文献
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Properties of runaway electron beams and x-ray radiation in a nanosecond volume discharge in air at atmospheric pressure are
investigated, and results of recent studies in this direction are analyzed. A physical nature of forming runaway electron
beams and x-ray radiation in the nanosecond volume discharge is discussed.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 40–51, December, 2005. 相似文献
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Samsonov SV Phelps AD Bratman VL Burt G Denisov GG Cross AW Ronald K He W Yin H 《Physical review letters》2004,92(11):118301
A new method to generate ultrahigh-power microwave pulses compatible with mildly relativistic electron sources is proposed. This method involves a novel microwave compressor in the form of a metal helically corrugated waveguide, which can enhance the power of frequency-modulated nanosecond pulses up to the multigigawatt level. The results of the proof-of-principle experiments at kilowatt power levels are in good agreement with theory. 相似文献
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Laser-controlled switching of dc or rf signals up to the GHz range: A new field of laser application
W. Platte 《Optics & Laser Technology》1978,10(1):40-42
A new technique for high-speed optoelectronic modulation and switching of dc or rf signals up to the GHz range, using ‘fast’ laser-controlled silicon microstrip devices, has been developed. The technique is based on well known applications of photosensitive CdS or Si devices as switching or triggering elements in ‘slow’ circuitry. The switching actions are achieved via laser- excited highly conductive solid-state plasmas. Applying nanosecond or picosecond laser pulses permits dc pulses or microwave pulses as short as a single cycle to be generated, demonstrating the practical significance of laser application in future pulse shaping and sampling techniques. 相似文献
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N. O. Arkhipov I. A. Znamenskaya I. V. Mursenkova I. Yu. Ostapenko N. N. Sysoev 《Moscow University Physics Bulletin》2014,69(1):96-103
The space-time characteristics of a nanosecond combined volume discharge with preionization from a plasma sheet with a nanosecond duration in air (~200 ns) are investigated. The integral discharge radiation, radiation spectrum, and discharge current under conditions within the discharge volume, including gas-dynamic flow with a planar shock wave, are analyzed. It is shown that the volume discharge glow is homogeneous in the master phase. The glow in the area of the shock-wave front increases and its duration may be more than 2 μs. 相似文献
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Works on the physics of electron runaway in gases, developing a new understanding of formation of runaway electron beams in
gas discharge, are reviewed. Results of experiments with atmospheric-pressure gas-filled diodes, in which subnanosecond electron
beams with a record current amplitude were obtained, are reported. The properties of volume nanosecond discharge, allowing
to obtain such beams, are analyzed. 相似文献
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The energy and mass compositions of the plasma generated by a nanosecond coaxial discharge on the surface of high-pressure polyethylene at different polarities of the central electrode with and without a vacuum gap between the dielectric and the peripheral electrode are investigated. It is shown that a nanosecond coaxial discharge on a dielectric surface is an efficient source of high-energy multicharged ions. 相似文献
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Yang Yang Wen-Chun Wang De-Zheng Yang Li Jia Shuai Zhang 《Journal of Electrostatics》2012,70(4):356-362
A bi-directional nanosecond pulsed power supply is employed to generate diffuse dielectric barrier discharge in N2 using needle-plate electrode configuration at atmospheric pressure. Both discharge images and optical emission spectra of diffuse bi-directional nanosecond high-voltage pulsed dielectric barrier discharge are successfully recorded under severe electromagnetic interference. The diffuse performance of the discharge at different electrode gap distances is observed. The effects of pulse peak voltage, pulse repetition rate, electrode gap distance, He addition, and O2 addition on the optical emission spectra are investigated. The main physicochemical processes involved are discussed. 相似文献
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Electron temperature and electron number density are important parameters in the characterization of plasma. In this paper the electron temperature and electron number density of soil plasma generated by laser ablation combined with nanosecond discharge spark at different discharge voltages have been studied. Saha-Boltzmann plot and Stark broadening are used to determine the temperature and electron number density. It is proved that local thermal equilibrium is fulfilled in the nanosecond spark enhanced plasma. The enhanced optical emission, signal to noise ratio and the stability in term of the relative standard deviation of signal intensity at different spark voltages were investigated in detail. A relative stable discharge process was observed with use of a 10 kV discharge voltage under the carried experimental configuration. 相似文献
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Plasma-assisted flow control is of high industrial interest, but practical applications at full scale require a large surface of interaction. Nanosecond pulsed Dielectric Barrier Discharge (DBD) have demonstrated promising results of flow control, but their interacting region is limited to only a few cm2. In this paper, the conditions to extend a surface nanosecond DBD are documented. It is shown that a sliding discharge regime can fully fill an inter-electrode distance of 40 mm. This discharge regime promotes the formation of two hemispheric pressure waves originating from both air-exposed electrodes while an horizontal region of pressure gradient is also observed. 相似文献
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小型超宽谱高功率微波辐射系统由Tesla型100 kV级ns脉冲源、Peaking-Chopping型亚纳秒气体开关及TEM喇叭天线构成。系统重复运行频率100 Hz,辐射因子rEp值75 kV,主轴辐射场中心频率520 MHz,-3 dB频谱范围230~810 MHz。系统集成于一便携箱内,体积为80 cm50 cm26 cm,质量约45 kg。该系统结构紧凑,能够快速展开和撤收,可方便用于超宽谱高功率微波应用技术研究。 相似文献
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We describe mechanisms of microwave pulse shortening in radiation sources with the power of about 108 W based on interaction between relativistic electron beams of nanosecond duration and preformed plasma. The shortening is mainly due to the electron return flow through the plasma, which leads to a multiple decrease in the linear gain of the microwave by the relativistic electron beam and in the reflection coefficient of the plasma wave that provides the generator feedback. The ways to eliminate the effect of microwave pulse shortening are proposed. 相似文献
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Jin J. Kim 《Optical and Quantum Electronics》1991,23(4):S469-S476
A brief review of metal vapour lasers is presented with an emphasis on the recent progress made in advancing metal vapour laser technology and applications. It is anticipated that new types of metal vapour lasers will be developed which take advantage of recently observed behaviours of high pressure copper vapour lasers. For example, collisional excitation energy transfer may make it possible to develop efficient single wavelength copper vapour lasers at high pressures. Also, use of new discharge schemes such as high power microwave discharges may significantly advance the metal vapour laser technology. A variety of new applications should also be realized in the years to come.Supported in part by a grant from the U.S. National Science Foundation. 相似文献
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The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges. 相似文献
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采用纳秒脉冲电源,在静止空气条件下,开展了不同气压、放电距离和电压条件下的大体积纳秒脉冲放电实验研究.研究表明,当长度固定为200mm时,气压为250Pa时,随着电压的增大,放电区域从圆锥电极附近扩展到整个通道.当电压为12kV时,放电布满整个通道;随气压升高,初始放电电压增大.实验中发现在电压升高到一定程度时纳秒脉冲电离出现不稳定性,表现在气压相对较低时等离子体出现径向波动,气压相对较高时非平衡等离子体放电向电弧放电转变.分析认为,为了实现大体积均匀放电等离子体的产生,阻止放电不稳定性发生,应该采用上升沿时间更短,脉宽更小,电压更高的纳秒脉冲电源. 相似文献