Exponential frequency spectrum and Lorentzian pulses in magnetized plasmas
Exponential frequency spectrum and Lorentzian pulses in magnetized plasmas
复制标题
磁化等离子体中的指数频谱和洛伦兹脉冲
DOI：
10.1063/1.3023155
复制
发表时间：
2008
影响因子：
2.2
通讯作者：
T. Carter
中科院分区：
文献类型：
--
作者：
D. Pace;M. Shi;J. Maggs;G. Morales;T. Carter
两个不同的实验涉及大型等离子体柱中限制磁场的压力梯度，发现在离子回旋频率以下的频率上显示出指数频谱的宽带湍流。指数特征已经被追溯到具有洛伦兹时间签名的孤立脉冲的存在。这些脉冲是由压力梯度驱动的漂移-阿尔芬波的非线性相互作用产生的。在这两个实验中，脉冲的宽度都是窄分布的，从而产生了具有单一特征时间尺度的指数谱。脉冲的时间宽度被测量为漂移-阿尔芬波周期的一小部分。这些实验是在大型等离子体设备(LAPD-U)上进行的[W.Gekelman等人，Rev.Sci。Instrum。62,2875(1991)]由加州大学洛杉矶分校的基础等离子体科学设施运营。其中一项实验涉及一种受控的纯电子温度梯度。
Two different experiments involving pressure gradients across the confinement magnetic field in a large plasma column are found to exhibit a broadband turbulence that displays an exponential frequency spectrum for frequencies below the ion cyclotron frequency. The exponential feature has been traced to the presence of solitary pulses having a Lorentzian temporal signature. These pulses arise from nonlinear interactions of drift-Alfven waves driven by the pressure gradients. In both experiments the width of the pulses is narrowly distributed resulting in exponential spectra with a single characteristic time scale. The temporal width of the pulses is measured to be a fraction of a period of the drift-Alfven waves. The experiments are performed in the Large Plasma Device (LAPD-U) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] operated by the Basic Plasma Science Facility at the University of California, Los Angeles. One experiment involves a controlled, pure electron temperature gradient associated...