Modelling of microwave heating and current drive at STEP

为了在未来的核聚变发电系统中有效地非感应驱动等离子体电流并支持稳态运行，使用多种机制，特别是电子回旋电流驱动（ECCD）和电子伯恩斯坦波（EBW）的激发，是非常可取的。这些工艺的应用可以是分开的，即对于低密度等离子体ECCD可以优选，而EBW-CD可以用于高密度等离子体。当等离子体条件允许两种机制同时使用时，也存在这样的制度。该项目的目的之一将是进行研究，以得出和了解转换加热机制的标准，即从ECCD转换为EBW-CD或同时使用两者。等离子体在时间上的演变也唤起了改变射频频率和射频波束发射方向以及用于驱动电流的功率调制的可能性。还将考虑决定射频波束变化的标准：频率、功率、方向，以提供保持稳定和连续运行的路线图。还应分析所选参数在给定平衡态的等离子体参数发生微小变化时的稳定性。虽然研究将从一般角度进行，但在项目期间将考虑考虑特定STEP工程要求的特定STEP设计，并将其用作参数优化的驱动因素。该项目将基于分析和数值研究，使用一组代码，如GENRAY， CQL3D和JETTO。UKAEA也在开发内部代码，用于提供CQL3D和GENRAY的基准测试。

To effectively drive plasma current non-inductively and support steady-state operation in future fusion power generation systems, the use of a combination of mechanisms, specifically Electron Cyclotron Current Drive (ECCD) and the excitation of Electron Bernstein Waves (EBW), are highly desirable. The application of these process may be separate i.e. for low density plasmas ECCD can be preferable while EBW-CD can be used for high density plasma. There are also regimes when plasma conditions are such that both mechanisms can be simultaneously employed. One of the aims of the project will be to carry out studies to derive and understand the criteria for switching the heating mechanisms i.e. from ECCD to EBW-CD or employing both simultaneously. The evolution of the plasma in time also evokes the possibility of varying the RF frequencies and the launch direction of the RF beams and modulation of the power used to drive the currents. The criteria which dictate the changing of the RF beams: frequencies, powers, directions will be also considered to provide the roadmap to maintain stable and continuous operation. The stability of the chosen parameters in regards with small variations of plasma parameters for given equilibria should be also analysed. Although the studies will be carried out from general perspectives, the specific STEP design which takes into consideration specific STEP engineering requirements, will be considered during the project and used as a driver for the parameter optimisations.The project will be based on analytical and numerical studies using a set of codes like GENRAY, CQL3D and JETTO. UKAEA are also developing in-house codes which will be used to provide benchmarking of CQL3D and GENRAY.