Numerical investigation of energetic electrons in RF-wave driven spherical Tokamak plasmas

与化石、核能或可再生能源等传统的主要能源选择相比，聚变的概念具有许多吸引人的特点。在安全方面，燃料储备、对环境的最小破坏以及能效聚变可能是未来世界能源供应的主要贡献者。然而，与聚变概念相关的非常困难的科学和工程挑战必须得到解决，已知的问题正在通过全球聚变研究计划得到解决。为了实现稳定的热核聚变反应，加热等离子体、提高和保持等离子体电流的复杂过程起着至关重要的作用。使用特定频谱的RF波的应用构成了满足这些需求的一种很有前途的有效程序。然而，低密度等离子体中的高能电子对托卡马克构型中上升过程的稳定性和效率的显著影响还没有得到详细的研究。该研究项目的目标是通过新的数值方法研究高能电子在无感应上升过程中的作用，从而开发出更有效的上升过程。为了达到这一目标，我们采用了一个非线性磁流体流体解算器来处理高能电子，并利用实验数据和参考数值模拟的结果对其进行了扩展。对一个研究高能电子作用的真实球形托卡马克组态的结果进行了分析，采用了MEGA和全波解算器相结合的方法。

The concept of fusion is characterized by many attractive features compared to conventional major energy options such as fossil, nuclear, or renewable sources. In terms of safety, fuel reserves, minimal damage to the environment, and efficiency fusion could represent a major contributor to the world's energy supply in the future. However, very difficult scientific and engineering challenges that are associated with the fusion concept have to be tackled and the known issues are being solved by global fusion research programs. To realize a stable thermonuclear fusion reaction the complex procedures to heat up the plasma and to ramp up and maintain the plasma current play a fundamental role. The application of RF-waves using specific spectra constitutes a promising and efficient procedure to meet these needs. However, the significant influence of energetic electrons in low-density plasmas on the stability and efficiency of the ramp-up procedure in Tokamak configurations has not been investigated in detail. The goal of the research project is to investigate the role of energetic electrons during the induction-free ramp-up process via novel numerical methods and consequently to develop more efficient ramp-up procedures. To reach the goal a non-linear magneto-hydrodynamic solver which is coupled with a kinetic particle formulation (MEGA) is adapted to deal with energetic electrons and extended by a modelled distribution function of electrons by using experimental data and results of reference numerical simulations. The analysis of the results of a realistic spherical Tokamak configuration investigating the role of energetic electrons is attended with MEGA coupled with a full-wave solver.