ELECTROSTATIC INSTABILITIES IN FINITE MIRROR-CONFINED PLASMAS
ELECTROSTATIC INSTABILITIES IN FINITE MIRROR-CONFINED PLASMAS
复制标题
有限镜面约束等离子体中的静电不稳定性
DOI：
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发表时间：
1966
期刊：
影响因子：
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通讯作者：
M. Rosenbluth
中科院分区：
文献类型：
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作者：
R. Post;M. Rosenbluth
从理论上研究了磁镜约束等离子体中可能遇到的三类静电不稳定性：（A）对流型，本质上类似于微波激射器，波基本上平行于场线传播;（B）非对流（绝对）不稳定性，在存在径向密度梯度的情况下产生;（C）（B）的极限情况，不需要径向密度梯度来激发。所有这三种不稳定性都源于粒子分布的损失锥性质，它们都表现出敏感地依赖于分布函数形状的起始或增长临界条件。这些条件是最少的限制等离子体已达到碰撞平衡的状态，在封闭领域的高镜比。在这个极限中，（C）消失了，（A）和（B）所施加的临界条件没有受到不适当的限制。特别地，在高等离子体密度下，需要：（1）为了相对于（A）的足够稳定性，镜之间的等离子体的长度必须不大于约300至500个离子轨道半径，以及（2）为了满足由（B）施加的条件（关于径向密度梯度），横向于场的等离子体尺寸也必须具有相同的数量级;即，等离子体必须是大致球形的。还给出的例子表明，高峰值分布的限制导致所需的条件的数量级更严格的比那些发现良好的随机分布。
Three classes of electrostatic instabilities deemed likely to be encountered in magnetic mirror‐confined plasmas are examined theoretically: (A) a convective type, maser‐like in nature, with waves propagating essentially parallel to the field lines; (B) a nonconvective (absolute) instability, arising in the presence of radial density gradients; and (C) a limiting case of (B), not requiring radial density gradients for its stimulation. All three instabilities, which owe their origin to the loss‐cone nature of the particle distributions, exhibit critical conditions for onset or growth that are sensitively dependent on the shape of the distribution functions. These conditions are least restrictive for plasmas that have reached a state of collisional equilibrium in confining fields of high mirror ratio. In this limit (C) disappears and the critical conditions imposed by (A) and (B) are not unduly restrictive. In particular, at high plasma densities it is required: (1) for adequate stability against (A), the length of the plasma between the mirrors must not be greater than about 300 to 500 ion‐orbit radii, and (2) to satisfy conditions (on the radial density gradient) imposed by (B), the plasma dimensions transverse to the field must also be of the same order; i.e., the plasma must be roughly spherical. Examples are also given which show that the confinement of highly peaked distributions leads to required conditions of orders of magnitude more restrictive than those found for well‐randomized distributions.