Lagrangian invariants of trapped electron dynamics in tokamaks
Lagrangian invariants of trapped electron dynamics in tokamaks
复制标题
托卡马克中俘获电子动力学的拉格朗日不变量
DOI：
10.1063/1.1331565
复制
发表时间：
2001
影响因子：
2.2
通讯作者：
X. Qiu
中科院分区：
文献类型：
--
作者：
X. Peng;X. Qiu
俘获电子动力学在具有正向或反向剪切的一般托卡马克磁场中被考虑。从俘获电子流体的连续性、能量演化和运动方程以及拉格朗日不变量的定义出发，严格求出隐藏在动力学中的拉格朗日不变量：L=ln[(n/B)c1(T/B2/3)c2]，其中c1和c2为无量纲可变参数，c1∝c2。它产生 n/B=const 和 T3/2/B=const。进而，据此可知<n>ψq(ψ)=const，<T3/2>ψq(ψ)=const。前一个不变量定性地拟合了许多托卡马克的实验数据；后者可用于解释在反剪切托卡马克等离子体中观察到的稳态空心 T 剖面（相应的空心 j 剖面）。
The trapped electron dynamics is considered in general tokamak magnetic field with positive or reversed shear. Starting from the continuity, energy-evolution, and motion equations of the trapped electron fluid and the definition of Lagrangian invariant, the Lagrangian invariants hidden in the dynamics are strictly found: L=ln[(n/B)c1(T/B2/3)c2], where c1 and c2 are dimensionless changeable parameters and c1∝c2. It yields n/B=const and T3/2/B=const. Further, based on them it is shown that 〈n〉ψq(ψ)=const and 〈T3/2〉ψq(ψ)=const. The former invariant qualitatively fits the experimental data in many tokamaks; the latter may be used to explain the steady-state hollow T-profile (the corresponding hollow j-profile) observed in reversed shear tokamak plasmas.