ECR离子源微波窗损伤机理研究

Study on Damage Mechanism of Microwave Window in ECR Ion Source

强束流下微波窗损坏是限制2.45 GHz电子回旋共振(ECR)离子源寿命的主要原因,为延长离子源使用寿命,对ECR离子源微波窗损伤机理进行了研究。利用有限元软件分别计算了Al 2O 3陶瓷微波窗在微波、等离子体和回流电子束作用下的温度及应力分布。计算结果表明,在微波和等离子体作用下,微波窗边缘处应力最大,在电子束作用下,微波窗中心位置应力最大。增强水冷效果可降低微波和等离子体对微波窗的影响,增加Al 2O 3陶瓷微波窗表面氮化硼(BN)的厚度可降低电子束的影响,从而减少微波窗损坏概率,延长离子源寿命。

The microwave window of 2.45 GHz electron cyclotron resonance(ECR)ion source is a lossy component when it works on intense ion beam DC mode,resulting in limited service life.In order to study the damage mechanism of microwave window,the finite element software was used to calculate the temperature and stress distributions of Al 2O 3 ceramic microwave window under the effect of the microwave,plasma and backstreaming electrons.The calculation result shows that the maximum Von Mises stress is at the edge of the microwave window under the effect of microwave and plasma,while under the effect of the electron beam,the largest stress is at the center of the microwave window.Enhancing water-cooling performance can reduce the influence of microwave and plasma on microwave window,and increasing thickness of BN can protect the window from electron beam more effectively.The combination of these two methods is feasible and effective in practice to extend the service life of the ECR ion source.