Phase mixing and echoes in a pure electron plasma
Phase mixing and echoes in a pure electron plasma
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纯电子等离子体中的相混合和回波
DOI：
10.1063/1.1885006
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发表时间：
2005
影响因子：
2.2
通讯作者：
T. M. O'Neil
中科院分区：
文献类型：
--
作者：
J. Yu;C. Driscoll;T. M. O'Neil
二维(2D)流体回波是在两个外部激励波被衰减后自发出现的双共振波，清楚地证明了空间朗道衰减的可逆性。低噪声电荷耦合器件相机直接拍摄到了无粘阻尼，或称相位混合，这显示了密度微扰的螺旋卷曲。令人惊讶的是，基本回波特性符合一个简单的非线性弹道理论，该理论忽略了所有集体(即模式)效应。此外，简单的2D图像被导致依赖于VZ的θ漂移的端部限制场破坏，因此观测到的回波必须被解释为单独的阻尼和单独的回波速度级的叠加。最大回波寿命符合描述速度级之间弱碰撞速度散射的理论。此外，大的第二波激发使回声衰减的速度比碰撞快5倍。
The two-dimensional (2D) fluid echo is a spontaneous appearance of a diocotron wave after two externally excited waves have damped away, explicitly demonstrating the reversible nature of spatial Landau damping. The inviscid damping, or phase mixing, is directly imaged by a low-noise charge-coupled device camera, which shows the spiral wind-up of the density perturbation. Surprisingly, the basic echo characteristics agree with a simple nonlinear ballistic theory that neglects all collective (i.e., mode) effects. Also, the simple 2D picture is violated by end confinement fields that cause vz-dependent θ drifts, so the observed echo must be interpreted as a superposition of separately damping and separately echoing velocity classes. The maximal echo lifetimes agree with a theory describing weak collisional velocity scattering between velocity classes. In addition, large second wave excitations degrade the echo up to 5× faster than collisions.