Hybrid magnetohydrodynamic-particle simulation of linear and nonlinear evolution of Alfven modes in tokamaks
Hybrid magnetohydrodynamic-particle simulation of linear and nonlinear evolution of Alfven modes in tokamaks
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DOI：
10.1063/1.872997
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发表时间：
1998-10
影响因子：
2.2
通讯作者：
S. Briguglio;F. Zonca;G. Vlad
中科院分区：
文献类型：
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作者：
S. Briguglio;F. Zonca;G. Vlad
采用MHD-粒子混合模拟程序，通过求解电磁场的MHD（magnetohydrofluidic）方程和高能离子布居的Gyrocenter Vlasov方程，研究了托卡马克装置中中等环圈数（n）剪切Alfven模的线性和非线性特性。不稳定的环形Alfven本征模（TAE）和它们的动力学对应物的存在示出的能量离子压力梯度的低值。在某一阈值以上，高能粒子连续模式（ETM）不稳定，增长率随着高能粒子压力梯度的增加而快速增加。阈值显示出对n的逆依赖性。因此，高氮化合物在实际等离子体条件下可能不稳定。忽略MHD的非线性，为了简单起见，它表明，非线性TAE饱和似乎是由于在波的势阱中的共振高能离子的捕获。相反，饱和度的出现是因为...
Linear and nonlinear properties of moderate-toroidal-number (n) shear-Alfven modes in tokamaks are investigated by using a hybrid MHD-particle simulation code, which solves the coupled set of MHD (magnetohydrodynamic) equations for the electromagnetic fields and gyrocenter Vlasov equation for a population of energetic ions. The existence of unstable toroidal Alfven eigenmodes (TAE’s) and their kinetic counterpart is shown for low values of the energetic-ion pressure gradient. Above a certain threshold value, the energetic particle continuum mode (EPM) is destabilized, with growth rate fast increasing with increasing energetic-particle pressure gradient. The threshold shows an inverse dependence on n. High-n EPM’s could then be unstable in realistic plasma conditions. Neglecting MHD nonlinearities, for the sake of simplicity, it is shown that nonlinear TAE saturation appears to be due to the trapping of resonant energetic ions in the potential well of the wave. Saturation of the EPM occurs instead because ...