Numerical simulation of nonlinear ionization nonuniformities in nonequilibrium disk MHD generator
Numerical simulation of nonlinear ionization nonuniformities in nonequilibrium disk MHD generator
复制标题
非平衡盘MHD发生器非线性电离不均匀性的数值模拟
DOI：
10.1109/27.557481
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发表时间：
1997
影响因子：
1.5
通讯作者：
S. Kabashima
中科院分区：
文献类型：
--
作者：
A. Sokolov;S. Kabashima
通过数值模拟研究了盘式磁流体动力学（MHD）发生器中非平衡Ar-Cs等离子体中有限振幅初始扰动引起的电离不均匀性的形成和演化，模拟在与种子部分电离区域、完全电离线性等离子体稳定区域相对应的宽电子温度区间内进行。 种子，以及对应于高电子温度下 Ar 部分电离的不稳定性区域。在时间 t=0 时，将电子温度和密度的有限振幅初始扰动引入均匀等离子体分布中，并计算决定不稳定性发展的临界振幅。采用不同空间尺度的随机函数构造初始扰动，将结果与平面电离波非线性理论计算的临界振幅进行比较，发现在电子温度低于5500 K时，临界振幅的温度依赖性和非线性波的结构与非线性理论吻合较好，在稀有气体部分电离对应的电子温度区域 (T/sub e/>5500 K)，氩原子的有限电离率对于不稳定性分析至关重要，在此区域等离子体稳定性裕度比非线性理论预测的要宽，与高电子温度(T/sub e/>5500 K)下的不均匀性相比，氩离子数密度的不均匀性在不稳定性发展中起主导作用。 T/sub e/ 在最初的干扰中，。
The formation and evolution of the ionization nonuniformities from initial disturbances of finite amplitude in the nonequilibrium Ar-Cs plasma in a disk magnetohydrodynamic (MHD) generator is studied by the numerical simulation, The simulations are carried out in the wide interval of electron temperatures corresponding to the region at which the seed partially ionizes, the region of the linear plasma stability at the fully ionized seed, and the region of the instability corresponding to the partial ionization of Ar at high electron temperatures. Initial disturbances of finite amplitude in electron temperature and density are introduced at the time t=0 into the homogeneous plasma distribution, and the critical amplitudes determining the development of the instability are calculated. The initial disturbances are constructed using random functions with different spatial scales, The results are compared with the calculation of the critical amplitudes from the nonlinear theory of the plane ionization waves, It is found that at electron temperatures lower than 5500 K, the temperature dependence of the critical amplitudes and the structure of the nonlinear waves agree well with the nonlinear theory, In the electron temperature region corresponding to the partial ionization of the noble gas (T/sub e/>5500 K), the finite ionization rate of argon atoms is essential for analysis of the instability, In this region the margin of the plasma stability is wider than it is predicted by the nonlinear theory, The nonuniformity in the argon ion number density plays the dominating role in the instability development at high electron temperatures (T/sub e/>5500 K) in comparison with the nonuniformity in T/sub e/ in the initial disturbances,.