Growth of filaments and saturation of the filamentation instability
Growth of filaments and saturation of the filamentation instability
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DOI：
10.1063/1.3345824
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发表时间：
2010-03
影响因子：
2.2
通讯作者：
M. Gedalin;M. Medvedev;M. Medvedev;M. Medvedev;A. Spitkovsky;V. Krasnoselskikh;M. Balikhin;A. Vaivads;S. Perri
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文献类型：
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作者：
M. Gedalin;M. Medvedev;M. Medvedev;M. Medvedev;A. Spitkovsky;V. Krasnoselskikh;M. Balikhin;A. Vaivads;S. Perri
逆流光束的成丝不稳定性是一种非共振水动力型不稳定性，其生长速率是波长（尺度）的光滑函数。结果，所有不稳定波长的扰动发展，并且由于可用电流的饱和，生长饱和。对于给定的尺度，饱和时的磁场与尺度成正比。结果，不稳定性在近似线性状态下发展，当达到相应波长的饱和时，不稳定模停止增长。在每一时刻，磁场都有一个占主导地位的尺度，这个尺度就是在这个特定时刻达到饱和的尺度。较小的尺度不会消失，可以很容易地在当前的结构中区分出来。当由于减速导致的流动离子能量损失与初始离子能量相当时，不稳定性的总体增长停止。
The filamentation instability of counterstreaming beams is a nonresonant hydrodynamic-type instability whose growth rate is a smooth function of the wavelength (scale). As a result, perturbations with all unstable wavelengths develop, and the growth saturates due to the saturation of available current. For a given scale, the magnetic field at saturation is proportional to the scale. As a result, the instability develops in a nearly linear regime, where the unstable modes stop growing as soon as the saturation of the corresponding wavelength is reached. At each moment there exists a dominant scale of the magnetic field which is the scale that reached saturation at this particular time. The smaller scales do not disappear and can be easily distinguished in the current structure. The overall growth of the instability stops when the loss of the streaming ion energy because of deceleration is comparable to the initial ion energy.