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首页> 外文会议>International Congress on Plasma Physics >Nonlinear Dynamical Analysis of Two Current-Driven Low-Frequency Instabilities in a Magnetised Plasma Column
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Nonlinear Dynamical Analysis of Two Current-Driven Low-Frequency Instabilities in a Magnetised Plasma Column

机译：磁化等离子体柱中两次电流驱动的低频不稳定性的非线性动力学分析

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By drawing an electron current along the field lines of a magnetised plasma column, several low-frequency in-stabilities can be excited. Many such experiments have been performed in Q-machines which produce an alkaline plasma of about 10~9 cm~(-3) density, confined by a B-field of about 0.2 T. If the collector, which draws the current, has a radius smaller than that of the plasma column but larger than a few ion gyroradii, the electrostatic ion-cyclotron instability (EICI) is predominant, but also the potential relaxation instability (PRI) can appear and there can be a strong interaction between the two. The frequency of the EICIf_(EICI) is slightly above the ion gyrofrequency Ω_i = eB/m_i, whereas that of the PRIf_(PRI) is given by the axial ion transit time through the system. We have investigated this interaction in the Innsbruck Q-machine in a potassium plasma in the case when the amplitudes of the two instabilities have similar values. In our case, for B = 0.13 T the interaction leads not only to a strong modulation of the amplitude but also of the frequency of the EICI by the PRI. Our results have indicated that the EICI frequency as such decreases with increasing strength of the exciting electron current, which effect can be explained by electron-neutral impact ionisation processes in front of the collector. In order to clarify the strong interaction between the two instabilities, the experimental results have been subject to a nonlinear dynamical analysis, which delivered the autocorrelation function and enabled us to reconstruct the state space of the phenomenon and to simulate the signal in a special case. These results are presented in this contribution.
机译：通过沿着磁化等离子体塔的场线绘制电子电流，可以激发几个低频稳定性。许多这样的实验已经在Q机器中进行，其产生约10〜9cm〜（-3）密度的碱性等离子体，其由约0.2吨的B字段限制。如果收集器，则绘制电流，具有a半径小于等离子体柱的半径，但大于几个离子陀螺仪，静电离子 - 回旋加速器不稳定性（Eici）是主要的，但也可以出现潜在的松弛不稳定（PRI），并且两者之间可能存在强烈的相互作用。 EICIF_（EICI）的频率略高于离子陀螺仪ω_I= EB / M_I，而PRIF_（PRI）的频率通过系统通过轴向离子传输时间给出。我们在钾等离子体中调查了Innsbruck Q-Machion的这种相互作用，在两个不稳定性的幅度具有相似的值的情况下。在我们的情况下，对于B = 0.13 T，交互不仅引导到PRI的强度调制而且对EICI的频率进行了强烈的调制。我们的结果表明，EICI频率随着励磁电子电流的增加而增加，其效果可以通过收集器前面的电子中性冲击电离过程来解释。为了澄清两个不稳定性之间的强烈相互作用，实验结果一直受到非线性动态分析，其传递自相关函数并使我们能够重建现象的状态空间并在特殊情况下模拟信号。这些结果呈现在这一贡献中。

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