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对于磁约束直流等离子体炬,用氩-氢等离子体的放电体系,研究了等离子体炬几何结构、真空室气压、弧电流、外磁场与比变化等对等离子体炬放电特性的影响。得到了影响等离子体炬宏观和微观参数变化的一些基本规律。 相似文献
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外磁场对直流等离子体炬放电特性的影响 总被引:1,自引:1,他引:0
介绍了新研制的磁约束直流等离子矩设备,计算了螺旋管线圈的磁场分布,通过实验研究了磁场变化对等离子体矩放电特性和伏安特性的影响。 相似文献
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闭式等离子体可以克服等离子体隐身技术在开放环境中等离子体难以维持及能耗过大的问题。针对等离子体隐身应用,设计了一种封闭式的等离子体发生装置,选用微秒脉冲电源,以氩气为工质气体,在低气压环境下进行了放电实验。采用发射光谱法,测量了密闭腔体内部厚度方向上的Ar谱线强度,并将碰撞-辐射模型用于分析等离子体参数的分布规律。当放电参数确定时,给定电子温度和电子密度,可通过碰撞-辐射模型计算得到2p能级上的布居分布比值,将其与从光谱数据中得到的布居分布比值进行比较,当差异值最小时,即可确定相应的等离子体参数。通过对电子温度在1~5 eV范围内的2p9和2p1能级布居分布比值进行计算,分析了碰撞-辐射模型计算可能存在的误差。实验结果表明,在厚度方向上,封闭式腔体中的等离子体电子密度达到1011 cm-3量级且呈一定的梯度分布,但变化幅度不大,其分布情况有利于等离子体隐身技术的应用。 相似文献
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直流辉光放电冷等离子体在高分子材料表面改性上的应用 总被引:2,自引:0,他引:2
报道了利用直流辉放光电正柱区产生冷气离子体对高分子材料进行表面改性的工作,阐述了它在纺织材料和非极性塑料制品表面改性上的应用,讨论了高分子材料等离子体表面改性的机理和等离子体参数的选择。 相似文献
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用光谱学方法研究不同放电等离子体粒子约束 总被引:2,自引:2,他引:0
本文用光谱学方法研究在HL-1装置上LHCD及ECRH等离子体,弹丸注入等离子体,偏压电极与偏压孔栏等离子体粒子约束特性。结果表明:在弹丸注入使用正向偏压电极与偏压孔栏期间,等离子体粒子约束行到改善,较低密度下(^ne<2.0×10^1^3cm^-^3),LHCD脉冲期间粒子约束得到改善;而当密度^-ne大于2.0×10^1^3cm^-^3时,等离子体约束变坏。ECRH脉冲期间粒子约束得不到改善。 相似文献
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Magnetic field has been applied to a copper vapor laser with an intention of improving the laser characteristics by inner gas convection. The convection induced by the J×B cross-field discharge (the Lorentz force) is used for partially replacing or mixing the laser medium in a highly heated discharged region with relatively cold gas surrounding the region. It is observed that the output power increases with the increase of the magnetic field. A 23% increase in the output power is obtained with a magnetic field of 150 gauss. The cross-field discharge causes an increase in the peak discharge voltage and a reduction in the initial part of discharge current (Phantom current). Based on the results observed, the possible mechanisms for increasing the power are discussed. 相似文献
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以临近空间高超声速飞行器以及航天器再入大气环境飞行过程"黑障"问题的研究为背景,进行了多相交流电弧放电实验装置的物理设计,建立了六相交流电弧等离子体实验平台(MPX-2015),在背景压力为500 Pa的亚大气压条件下获得了最大直径和长度分别达到14.0 cm和60.0 cm的等离子体射流.研究了工作气体流量、真空腔压强、电极间距以及弧电流等因素对等离子体自由射流和冲击射流特性的影响规律.结果表明:在实验参数范围内,真空腔压强对等离子体的射流特性影响最为显著,等离子体自由射流的长度和直径以及冲击钝体条件下的鞘套有效工作长度和厚度均随着压强的降低而增大;提高沿电极环缝注入的工作气体流量或弧电流亦有利于等离子体鞘套尺寸的增加.上述工作有助于进一步开展临近空间飞行器与其周围复杂介质环境间复杂的气动热效应和"黑障"问题的研究. 相似文献
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通过Fokker-Planck模拟,研究了等离子体在任意强度的直流电场中产生电流的过程以及电子分布函数的演变过程.研究发现,不同强度的电场中等离子体的行为存在着明显的差别.在弱电场中,电流与电场满足Spitzer公式,且电流产生的响应时间约等于撤销电场后电流衰减的弛豫时间;在中等强度的电场中,电子分布函数呈现为静止Maxwell分布和漂移Maxwell分布之和,而且在中等强度或者强直流电场中弛豫时间也将远远大于响应时间.根据电子分布函数的演变规律,推导了一组类似于流体力学方程的公式,这组方程像Spitzer公式一样简便地描述了等离子体中电流与电场的关系,并且对电场强度没有限制.数值模拟显示这组方程比Spitzer公式更适用于等离子体的混合粒子模拟中.
关键词:
等离子体电流
电子分布函数
Fokker-Planck模拟
Spitzer公式 相似文献
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变形镜驱动器正负电源加电或者断电不同步,导致其在加电瞬间或者断电瞬间,输出端会输出一个-38.0V和86.0V的冲击电压,这个冲击电压使得变形镜在未开始工作时就产生了较为严重的面形畸变,为此研制了基于微处理器的软启停直流电源,它输出两路按一定时序变化的输出电压作为后续两个继电器的控制端,再通过这两个继电器分别控制变形镜驱动器正、负电源的导断,从而使得变形镜驱动器的正负电源同时加载或者卸载。在硬件平台了进行了实验验证,结果表明,使用软启停直流电源后,变形镜驱动器加电瞬间或断电瞬间,其产生的脉冲电压的峰-峰不超过0.45V,远远小于未使用软启停直流电源前的冲击电压,满足了系统的设计要求。 相似文献
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I. Matsui 《Journal of nanoparticle research》2006,8(3-4):429-443
FePt nanoparticle is expected as a candidate for the magnetic material of the high density recording media. We attempted to synthesize FePt alloy nanoparticles using 13.56 MHz glow discharge plasma with the pulse operation of a square-wave on/off cycle of plasma discharge to control the size of nanoparticles. Vapors of metal organics, Biscyclopentadienyl iron (ferrocene) for Fe and (Methylcyclopentadienyl) trimethyl platinum for Pt, were introduced into the capacitively coupled flow-through plasma chamber, which consisted of shower head RF electrode and grounded mesh electrode. Synthesis experiments were conducted at room temperature under the conditions of pressure 0.27 Pa, source gas concentration 0.005 Pa, gas residence time 0.5 s and plasma powers 60 watts. Pulse width for plasma duration was chosen from 0.5 to 30 s and plasma off period was 4 s to each pulse operation. Visual observations during the particle growth showed plasma emission in the bulk region was increased with the particle growth. These were theoretically explained by using the model for both transient particle charging in the plasma and single particle behavior in the stationary plasma as well as assuming the similarity between the negative charged particle and negative gas containing plasma. Synthesized nanoparticles were directly collected onto TEM grid, which was placed just below the grounded mesh electrode in the plasma reactor downstream. TEM pictures showed two kinds of particles in size, one of which was nanometer size and isolated with crystal structures and the other appeared agglomerate of nanometer size particles. The size of agglomerated particle was controlled in the 10–120 nm range by varying the plasma-on time from 0.5 to 30 s, although the nanometer size particles did not change. The composition of FePt alloy particles could be altered by adjusting the source gas feed ratio. Also magnetization of FePt nanoparticles was measured by use of SQUID (superconducting quantum interference device) magnetometry measurements. As-synthesized FePt nanoparticles did not exhibit loop-shape characteristic, which indicated superpamagnetic property. Annealed nanoparticles with the composition of Fe58Pt42 at 650°C in atmospheric hydrogen showed clear hysterisis loop with the coercivity as large as 10 KOe. 相似文献
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The direct current comparator resistance bridge, Model 9975, manufactured by Guildline Instruments, Inc., which permits electrical
resistance measurements up to eight digits, has been fully automated. Details of this automation are described in this paper.
The performance of the automated bridge is demonstrated with applications to electrical resistivity studies on some metallic
alloys. 相似文献