Space-charge effects on drift dominated electron and plasma motion
Space-charge effects on drift dominated electron and plasma motion
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DOI：
10.1088/0022-3727/14/11/010
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发表时间：
1981-11
期刊：
影响因子：
--
通讯作者：
R. Morrow;J. Lowke
中科院分区：
文献类型：
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作者：
R. Morrow;J. Lowke
电子和离子的连续性方程和泊松方程求解的脉冲的运动（i）电子和（ii）等离子体中施加的电场约6千伏cm-1。对于在氮气中，在293 K的温度和12 kPa的压力下考虑的情况，其中E/N约为2*10-15 V cm-2，并且漂移距离为几厘米，电子漂移超过扩散。等离子体脉冲中电子和离子的相对运动具有与低场和低压力的双极扩散运动特性非常不同的特性。半径约为0.5 cm、密度约为1011 cm-3的电子脉冲由于空间电荷场而迅速传播，而与是否施加均匀电场无关。在均匀电场中，空间电荷效应增强了电子脉冲前沿的电场。对于密度为5*106 cm-3的初始中性等离子体，在均匀电场中，电子独立于离子移动。当密度增加，空间电荷是显着的，电子分布有一个特征陡峭的后缘和一个几乎平坦的前缘。在考虑的最高密度约1011 cm-3的电场减少到几乎为零的中心的等离子体的空间电荷效应。
The electron and ion continuity equations and Poisson's equation are solved for the motion of pulses of (i) electrons and (ii) plasma in an applied electric field of approximately 6 kV cm-1. For the cases considered in nitrogen at a temperature of 293K and at pressures of 12 kPa, where E/N approximately 2*10-15 V cm-2, and drift distances are a few cm, electron drift dominates over diffusion. The relative motion of electrons and ions in a plasma pulse have characteristic features very different from ambipolar diffusion motion characteristic of low fields and pressures. An electron pulse of radius approximately 0.5 cm and density approximately 1011 cm-3 spreads rapidly due to space-charge fields, regardless of whether a uniform electric field is applied. Space-charge effects enhance the electric field at the leading edge of an electron pulse in a uniform electric field. For an initially neutral plasma of density 5*106 cm-3 in a uniform electric field, electrons move independently of the ions. When the density is increased, and space charge is significant, the electron distributions have a characteristic steep trailing edge and an almost flat leading edge. At the highest densities considered of approximately 1011 cm-3 the electric field is reduced almost to zero at the centre of the plasma by space-charge effects.