On the formation of m = 1, n = 1 density snakes
On the formation of m = 1, n = 1 density snakes
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DOI：
10.1063/1.4793450
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发表时间：
2013-03
影响因子：
2.2
通讯作者：
L. Sugiyama
中科院分区：
文献类型：
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作者：
L. Sugiyama
m/n = 1/1螺旋离子密度“蛇”位于环形磁面q = 1附近，磁约束等离子体在电阻MHD中自然出现，当等离子体密度与压力分离时。非线性数值模拟表明，在q = 1附近施加螺旋密度扰动可以在q≥1时形成准稳态，其中T的平均符号与n相反。两个主要结果取决于n/n的大小和1/1内部扭结模式的潜在稳定性。对于小q<1的中心区域，中等的螺旋密度在q<1内部驱动一个新的、缓慢增长的非线性1/1内结，具有小n和∇p≃∇(nT)。热结核远离或垂直于q≃1附近的高密度区域，在锯齿状碰撞中保持蛇的密度。该模式类似于欧姆放电中重杂质离子蛇的早期阶段，包括最近在Alcator C-Mod中观察到的。对于更大、更不稳定的q<1区域，螺旋密度摄动…
The m/n = 1/1 helical ion density “snake” located near the q = 1 magnetic surface in a toroidal, magnetically confined plasma arises naturally in resistive MHD, when the plasma density evolves separately from pressure. Nonlinear numerical simulations show that a helical density perturbation applied around q = 1 can form a quasi-steady state over q≳1 with T of opposite average sign to n. Two principal outcomes depend on the magnitude of n/n and the underlying stability of the 1/1 internal kink mode. For a small q<1 central region, a moderate helical density drives a new, slowly growing type of nonlinear 1/1 internal kink inside q<1, with small n and ∇p≃∇(nT). The hot kink core moves away from, or perpendicular to, the high density region near q≃1, preserving the snake density during a sawtooth crash. The mode resembles the early stage of heavy-impurity-ion snakes in ohmic discharges, including recent observations in Alcator C-Mod. For a larger, more unstable q<1 region, the helical density perturbati...