ICRF天线多辐射带间功率互耦抑制方法的研究

The near-field antenna is usually adopted for the experiments of Ion Cyclotron Range of Frequency (ICRF) heating and current drive in the tokamaks. Basically, the antenna is designed with the structure of multiple current straps, so as to improve the total power capacity and provide the required wave spectrum of the antenna. However, due to the coupling of electric field and magnetic field and the electromagnetic wave reflected by plasma, there are obvious disadvantages of cross power among the straps, which seriously restricts the high-power steady-state operation of ICRF system. Based on the applicant’s latest research findings, a new method is proposed to cope with such mutual coupling by controlling the structure and then the admittance matrix of antenna. Through the combination of theoretical analysis, numerical simulation and experimental research, a set of ICRF antenna decoupling system will be designed and eventually verified in EAST. By the implementation of this project, it will not only fundamentally solve the issue about the mutual coupling among the straps of the ICRF antenna in EAST, but also provide the important technical solution for the main critical issue of the ITER ICRF antenna and feeder line design.

在托卡马克装置上，近场耦合天线通常被应用于离子回旋频率（ICRF）加热和电流驱动的实验研究中。该种天线基本上均采用多辐射带的结构设计，以提高整柄天线的功率容积和提供所需的天线波谱。多辐射带间由于彼此间的电场和磁场耦合以及等离子体反射的电磁波，存在明显的功率交叉互耦的不利特性，严重制约着ICRF系统的高功率、稳态运行能力。申请人基于已取得的最新研究发现，提出一种通过天线结构设计并控制其导纳矩阵来抑制多辐射带间功率互耦的全新方法。拟通过理论分析、数值模拟与实验研究相结合的研究方式，在EAST上设计一套ICRF天线去耦合系统，并进行验证与完善。通过此项目的实施，不仅从根本上解决EAST上ICRF天线辐射带间的功率互耦问题，而且也将为ITER装置上ICRF天馈线设计中亟待解决的难题，提供一种有效的解决方案。

在托卡马克装置上，离子回旋频率（ICRF）加热采用的是近场耦合天线，采用多辐射带设计。然而，多辐射带间存在明显的功率交叉互耦的不利特性，严重制约着ICRF系统的高功率、稳态运行能力。该项目提出一种通过天线结构设计并控制其导纳矩阵来优化和抑制多辐射带间功率互耦的新方法。主要研究内容包括天线功率互耦的仿真分析、关键核心部件去耦合装置研制、高反射系数下的监测和诊断系统搭建和实验测试研究。ICRF天线在37MHz工作频率下端口间耦合系数从-22dB优化到-58dB分贝，有效实现了端口隔离和辐射带间功率互耦抑制。对应传输线峰值驻波电压，在1.05MW功率下仅为15.7kV，系统的功率容积得到显著提升，实现了单柄天线最高2.1MW的EAST实验记录，达到世界同类装置先进水平。在长脉冲方面表现出良好的特性，实现了1.1MW/65s兆瓦级运行。通过本项目的实施，从根本上解决EAST上ICRF天线辐射带间的功率互耦问题，提升了EAST装置ICRF系统稳定性、功率注入水平和长脉冲运行能力，为EAST开展高水平ICRF物理实验研究提供了重要的技术支撑。