Sheath dynamics of electrodes stepped to large negative potentials
Sheath dynamics of electrodes stepped to large negative potentials
复制标题
电极的护套动力学步入大负电位
DOI：
10.1063/1.860513
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. G. Laframboise
中科院分区：
文献类型：
--
作者：
A. Calder;G. W. Hulbert;J. G. Laframboise
本文给出了电极周围等离子体鞘层随时间变化的粒子模拟结果，电极的电势从0突然变化到某个负值。假设周围的等离子体是各向同性和无碰撞的，电极是一个球体或无限长的圆柱体。考虑了高达− 1000 kTe/e的潜在步骤。研究了由势阶跃引起的鞘层振荡和等离子体振荡的时程和频谱。鞘层振荡（频率<ωp）中的能量通过非线性耦合逃逸到等离子体振荡（频率ωp）。鞘层-等离子体耦合的时间尺度强烈依赖于离子-电子质量比。线性和非线性离子声波都是由对电位阶跃的响应激发的。在一个小的圆柱形电极（半径1λD）附近，被捕获的离子被证明对鞘层离子密度有重要贡献。对于足够大的电势阶跃，圆柱形电极收集电流的瞬态峰值高度与离子-电子温度比有很强的依赖关系。本文用粒子模拟方法研究了电势突然从0变化到负值时，电极周围等离子体鞘层随时间变化的行为。假设周围的等离子体是各向同性和无碰撞的，电极是一个球体或无限长的圆柱体。考虑了高达− 1000 kTe/e的潜在步骤。研究了由势阶跃引起的鞘层振荡和等离子体振荡的时程和频谱。鞘层振荡（频率<ωp）中的能量通过非线性耦合逃逸到等离子体振荡（频率ωp）。鞘层-等离子体耦合的时间尺度强烈依赖于离子-电子质量比。线性和非线性离子声波都是由对电位阶跃的响应激发的。在一个小的圆柱形电极（半径1λD）附近，被捕获的离子被证明对鞘层离子密度有重要贡献。圆柱形电极收集电流的瞬态峰值高度与电极的电流密度有很强的相关性。
Results are presented of particle simulations of the time‐dependent behavior of the plasma sheath surrounding an electrode whose potential is abruptly changed from 0 to some negative value. The surrounding plasma is assumed isotropic and collisionless, and the electrode is a sphere or infinite cylinder. Potential steps up to −1000kTe/e are considered. The time histories and frequency spectra of sheath and plasma oscillations initiated by the potential step are studied. The energy in sheath oscillations (frequency <ωp) escapes by nonlinear coupling to plasma oscillations (frequency ωp). The time scale for sheath–plasma coupling depends strongly on the ion‐to‐electron mass ratio. Both linear and nonlinear ion acoustic waves are excited by the response to the potential step. Near a small (radius 1λD) cylindrical electrode, trapped ions are shown to make an important contribution to the sheath ion density. The height of the transient peak in collected current for a cylindrical electrode displays strong dependence on the ion‐to‐electron temperature ratio, for sufficiently large potential steps.Results are presented of particle simulations of the time‐dependent behavior of the plasma sheath surrounding an electrode whose potential is abruptly changed from 0 to some negative value. The surrounding plasma is assumed isotropic and collisionless, and the electrode is a sphere or infinite cylinder. Potential steps up to −1000kTe/e are considered. The time histories and frequency spectra of sheath and plasma oscillations initiated by the potential step are studied. The energy in sheath oscillations (frequency <ωp) escapes by nonlinear coupling to plasma oscillations (frequency ωp). The time scale for sheath–plasma coupling depends strongly on the ion‐to‐electron mass ratio. Both linear and nonlinear ion acoustic waves are excited by the response to the potential step. Near a small (radius 1λD) cylindrical electrode, trapped ions are shown to make an important contribution to the sheath ion density. The height of the transient peak in collected current for a cylindrical electrode displays strong depend...