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Current-drive theory in the presence of fluctuations

存在波动时的电流驱动理论

基本信息

批准号：
17560732
负责人：
TAGUCHI Masayoshi
金额：
$ 0.96万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560732/
关键词：
current drive plasma radio-frequency wave fluctuation anomalous transport DIA tokamak fusion

项目摘要

We have theoretically studied the current drive due to radio-frequency (rf) waves in the presence of electric and magnetic fluctuations and have obtained the following results:1. Starting from the relativistic Fokker-Planck equation in the presence of fluctuations and using the direct-interaction approximation (DIA), we have derived the equation for the ensemble-averaged distribution function, which can be used as a basic equation in developing the computational code for the rf current drive.2. We have found that the use of adjoint equation leads us to the more analytical method compared with directly solving the equation for the ensemble-averaged distribution function. By means of this adjoint method, the mean-squared width and the radial profile of rf-driven current density are explicitly calculated for various values of the collision frequency, and the amplitude and correlation lengths of fluctuations.3. The radial diffusion equation for the rf-driven current density and the analytic expression for the diffusion coefficient in this equation are presented. The explicitly calculated results show that the current profiles obtained by using the adjoint equation and the radial diffusion equation agree well in the range of interesting parameters.4. The spatially local (spatial Markovian) approximation is used in the formulations of 1-3. In order to study the spatial nonlocal effect, we have reformulated the theory without the use of local approximation, and have derived the integro-differential equation for the rf-driven current density. The effect of spatial nonlocality on the profiles of rf-driven current density is show to be not significant in the wide range of parameters.5. Using the idea of the subensemble averaged instead of conventional ensemble average, we have extended the DIA, and have applied to the rf-current-drive theory. I n th i s formulation, we can incorporate the effect of particle trapping in the fluctuating electric and magnetic filed.

我们从理论上研究了存在电磁涨落的情况下射频波的电流驱动，得到了以下结果：1。从涨落存在下的相对论性Fokker-Planck方程出发，利用直接相互作用近似（DIA），推导出了系综平均分布函数方程，该方程可作为开发射频电流驱动计算程序的基本方程.我们发现，使用伴随方程比直接求解系综平均分布函数的方程更具有分析性。通过这种伴随方法，明确地计算了不同碰撞频率、涨落幅度和关联长度下的射频驱动电流密度的均方宽度和径向分布.给出了射频驱动电流密度的径向扩散方程和扩散系数的解析表达式。显式计算结果表明，伴随方程和径向扩散方程得到的电流分布在感兴趣的参数范围内吻合较好.在1-3的公式中使用空间局部（空间马尔可夫）近似。为了研究空间非局域效应，我们在不使用局域近似的情况下重新建立了理论，并导出了射频驱动电流密度的积分微分方程。在较宽的参数范围内，空间非局域性对射频驱动电流密度分布的影响并不显著.利用子系综平均代替传统系综平均的思想，我们推广了DIA，并应用于射频电流驱动理论。在这个公式中，我们可以将粒子捕获在波动的电场和磁场的效果。