双驱动射频负氢离子源匹配网络设计与实验研究

Design and experimental study of matching networkfor dual drive RF negative hydrogen ion source

随着磁约束聚变实验装置对中性束注入器的输出束流强度与脉冲时间的要求越来越高,开展高功率大面积射频离子源的研究迫在眉睫。为了实现大面积、高密度均匀等离子体放电,基于多驱动射频离子源的设计是当前的发展趋势,而阻抗匹配网络是射频功率源将最大功率输送至线圈并耦合至等离子体的关键,故对其结构设计和调谐特性的研究是不可或缺的。基于前期在单驱动射频离子源的研究基础上,结合双驱动射频离子源的放电需求,开展了双驱动阻抗匹配网络优化结构的设计与分析,通过实验中对匹配网络的调谐,成功实现了140 kW高功率和25 kW/1 000 s长脉冲的稳定运行。随后在等离子体稳定放电的基础上研究了两个驱动器之间的功率分配均匀性问题,实验结果表明了该匹配网络的优化设计合理可行,上下驱动器的射频功率分配基本均匀。

With the increasing demand for the output beam intensity and pulse time of the neutral beam injectorin the magnetic confinement fusion experimental device,it is urgent to carry out research on high-power large-area RFion sources.It is the key to designing an impedance matching network that can deliver the maximum power of the RFpower source to the coil and couple it to the plasma,thus to achieve large-area,high-density and uniform plasmadischarge.Based on the previous research on single driver RF ion sources,the impedance matching network of dualdriver RF ion sources was optimized and analyzed.The key parameters of the matching network were calculated,andthe topology of the matching circuit was optimized.In the experiment,frequency tuning was used to tune the matchingnetwork.Stable and repeatable plasma discharge with 140 kW high power and 1000 s long pulse at 25 kW wasachieved under dual drive.Subsequently,based on stable plasma discharge,the issue of power distribution uniformitybetween the two drivers was studied.The experimental results indicate that the optimized design of the matchingnetwork is reasonable and feasible,and the RF power distribution of the upper and lower drivers is basically uniform,laying the foundation for the upcoming negative ion beam extraction in the CRAFT(Comprehensive Research fAcilityfor Fusion Technology)NNBI(neutral beam injection system)project.