Abstract:

Using the principle of quasi-optic, the new antenna of the electron cyclotron resonant heating(ECRH) system on the tokamak HL-2A has been designed. After being focused by the elliptical mirror and reflected by the plane mirror, 4 68GHz/500kW/1s electron cyclotron wave beams would be injected into the tokamak from one Æ350mm port to accomplish heating to the plasma. Based on the propagating theory of the fundamental Gaussian beam, it is gotten that at the centre of the cross section of the tokamak, the power density of each beam is 158MW•m^-2, and the power density radius, which means that the power density is reduced by a factor 1/e² compared to the power density at the centre of the beam, is 31.7mm. On the mirror, due to the focusing and reflecting, the ohmic loss and diffraction loss of the microwave beams are 0.27% and 0.64%, respectively. By the finite element analysis software ANSYS, some thermal analysis of the mirror have been done. The result shows that the highest temperature increase would be only 0.47℃ under 1s pulse load, so there is no need of any cooling.

Key words: ECRH, Antenna, Gaussian beam, HL-2A tokamak

摘要：

应用准光学原理设计了HL-2A装置电子回旋共振加热(ECRH)系统新的集束天线，该天线能使4束68GHz/500kW/1s电子回旋波通过椭球镜聚焦和平面镜的反射，从一个直径350mm装置窗口同时注入托卡马克，对等离子体实现加热。根据基模高斯束的传播原理得出，在装置环向横截面中心处单条波束的功率密度为158MW•m^-2，功率密度降为中心密度的1/e²的半径为31.7mm，微波束经过镜面聚焦和反射产生的欧姆损失和衍射损失分别为0.27%和0.64%。利用有限元分析软件Ansys对镜面进行热分析得到，在1s脉冲载荷下最大镜面温升仅为0.47℃，镜面可以自然冷却。

关键词: ECRH, 天线, 高斯束, HL-2A装置