Nonlinear electron magnetohydrodynamics physics. IV. Whistler instabilities
Nonlinear electron magnetohydrodynamics physics. IV. Whistler instabilities
复制标题
非线性电子磁流体动力学物理学。
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
K. Strohmaier
中科院分区：
文献类型：
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作者：
J. Urrutia;R. Stenzel;K. Strohmaier
在实验室均匀等离子体中，用磁环天线激发出一个非常大的低频哨声模。波磁场超过了周围的磁场，在一个极性上导致磁场反转，在另一个极性上形成类似于球峰的磁拓扑。这些传播的“哨声球马克”强烈地加速电子，并在其环形电流环中产生非麦克斯韦分布。据观察，在电流环中的局部激发的电子激发新的电磁不稳定性和发射哨声模式的频率无关的应用频率。发射也观察到从电子激发的X型中性线周围的天线。激发波的性质，如振幅，频谱，场拓扑结构，传播，极化，增长和阻尼进行了研究。波保持线性（B波<$B0），并将一小部分电子动能转换为波磁能（B波2 scin 2μ0 nkTe）。
A very large low-frequency whistler mode is excited with magnetic loop antennas in a uniform laboratory plasma. The wave magnetic field exceeds the ambient field causing in one polarity a field reversal, and a magnetic topology resembling that of spheromaks in the other polarity. These propagating “whistler spheromaks” strongly accelerate the electrons and create non-Maxwellian distributions in their toroidal current ring. It is observed that the locally energized electrons in the current ring excite new electromagnetic instabilities and emit whistler modes with frequencies unrelated to the applied frequency. Emissions are also observed from electrons excited in X-type neutral lines around the antenna. The properties of the excited waves such as amplitudes, frequency spectra, field topologies, propagation, polarization, growth, and damping have been investigated. The waves remain linear (Bwave⪡B0) and convert a small part of the electron kinetic energy into wave magnetic energy (Bwave2∕2μ0⪡nkTe).