Development of a prototype of ECH system without window for vacuum seal

在核聚变研究中，真空密封窗口是大功率ECH系统发展中最重要的问题之一。在这个项目中，我们测试了一个真空密封无窗的ECH系统。设计、制造并测试了工作在2次电子回旋加速器谐波下的48 GH_z可拆卸回旋加速器样机。然后拆除回旋管的真空密封窗口，用4m长的圆波导将回旋管直接连接到WT-3托卡马克的真空室。当托卡马克等离子体被破坏时，回旋管中的压力达到最大值。在托卡马克放电间隔后，管内压力恢复到初始值，这对回旋管的操作是没有问题的。我们确认回旋管和托卡马克同步运行没有问题。结果表明，无真空密封窗口的真空真空系统可以应用于核聚变研究。关于系统维护的问题还不清楚。它们将用于WT-3托卡马克的ECH实验。在像ITER这样的大型设施中，会有不同于小型设施的问题。需要进一步调查。

A window for vacuum seal is one of the most serious problems in the development of high power ECH system in fusion research. In this project, we tested an ECH system without windows for vacuum seal.A prototype of 48 GH_z demountable gyrotron operating at the 2nd electron cyclotron harmonics was designed , built and tested. Then the window for vacuum seal of the gyrotron was removed and the gyrotron was directry connected to the vacuum chamber of the WT-3 tokamak with a 4m long circular waveguide.The pressure in the gyrotron tube attains the maximum value when a tokamak plasma is disrupted. After the interval of tokamak discharge, the pressure in the tube is restored at the initial value which is no problem in operating the gyrotron.We confirmed that there is no problem in synchronized operation of the gyrotron and the tokamak.It can be cocluded that the ECH system without windows for vacuum seal can be applicable to fusion research.The problems about maitenance of the system are not clear. They will be clear in use for ECH experiments on the WT-3 tokamak.In a big facility something like ITER, there will be different kind of problems from small facilties. Further investigation will be required.