Characteristics of low-q disruptions in PBX
Characteristics of low-q disruptions in PBX
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PBX 中低 q 中断的特征
DOI：
10.1088/0029-5515/28/11/004
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
H. Takahashi
中科院分区：
文献类型：
--
作者：
S. Kaye;G. Jahns;A. Morris;S. Sesnic;K. Bol;M. Chance;P. Couture;R. Fonck;G. Gammel;W. Heidbrink;R. Kaita;H. Kugel;B. Leblanc;J. Manickam;N. Ohyabu;M. Okabayashi;M. Reusch;H. Takahashi
在普林斯顿贝塔实验中，在低q值（2.3 ≤ q <4.5）时，放电受到≤25 kHz前体振荡增长和锯齿状“碰撞”后的硬中断的限制。即使在α βt α远低于第一稳定区边界（α 2.5 μ 0 Ip/aBt）的放电中也会发生这种破坏，这种破坏要么立即发生，要么延迟几毫秒发生在这种前兆模式的崩溃之后，立即破坏主要发生在α βt α接近第一稳定区边界的放电中。最高的α βt α放电也表现出最快的增长时间和最高水平的边缘MHD活动。与前驱模式碰撞相关联的是高达30%的等离子体能量的损失;因此，对于非零延迟射击，碰撞而不是实际的破坏是等离子体能量的限制过程。延迟周期被解释为一个时期，在此期间，锁定模式，由几个环形组件的可比幅度，增长。由于与碰撞相关的能量损失，等离子体在延迟期间变得垂直不稳定。研究结果表明，即使在相对狭窄的低q值工作空间内，低q ^扰动的特性也具有连续性，主要依赖于α βt α的值。虽然理想的外部扭结不稳定性可能会引起越来越大的振荡，导致最终的破坏，不稳定性只在最低的q（≤3）和最高的α βt的边缘加权。研究结果表明，理想MHD理论范围之外的效应可能在低q值扰动中起重要作用。
At low qψ (2.3 ≤ qψ ≤ 4.5), in the Princeton Beta Experiment, the discharges are limited by a hard disruption following the growth and sawtooth-like 'crash' of a ≤25 kHz precursor oscillation. The disruption, which occurs even in discharges with ⟨βt⟩ well below the first stability regime boundary (≅2.5 μ0Ip/aBt), follows the crash of this precursor mode either immediately or with a delay of several milliseconds, with the immediate disruptions primarily occurring in the discharges with ⟨βt⟩ close to the first regime limit. The highest ⟨βt⟩ discharges also exhibit the fastest growth times and the highest level of edge MHD activity. Associated with the precursor mode crash is a loss of up to 30% of the plasma energy; thus, for non-zero delay shots, it is the crash and not the actual disruption that is the ⟨βt⟩ limiting process. The delay period is interpreted as a period during which a locked mode, consisting of several toroidal components of comparable amplitude, grows. Because of the energy loss associated with the crash, the plasma goes vertically unstable during the delay period. The results of this study indicate that even within the relatively narrow low-qψ operating space, there is a continuum in the characteristics of the low-q^ disruptions with a primary dependence on the value of ⟨βt⟩. While the ideal external kink instability may give rise to the growing oscillations that lead up to the ultimate disruption, the instabilities are weighted towards the edge only at the lowest qψ (≤3) and highest ⟨βt⟩. The results of this study indicate that effects outside the scope of ideal MHD theory may play a significant role in low-qψ disruptions.
影响因子：
3.3
作者：
A. Gibson;T. Sekiguchi;K. Lackner;S. Bodner;R. Hancox
通讯作者：
A. Gibson;T. Sekiguchi;K. Lackner;S. Bodner;R. Hancox