【作者】 董烨； 刘庆想； 庞健； 杨温渊； 周海京；

【Author】 DONG Ye;LIU Qing-xiang;PANG Jian;YANG Wen-yuan;ZHOU Hai-jing;School of Physical Science and Technology, Southwest Jiaotong University;Institute of Applied Physics and Computational Mathematics;Institute of Fluid Physics, China Academy of Engineering Physics;

【机构】 西南交通大学物理科学与技术学院； 北京应用物理与计算数学研究所； 中国工程物理研究院流体物理研究所；

【摘要】 本文利用蒙特卡罗与粒子模拟方法对金属无氧铜材料双边二次电子倍增的瞬时演化特性和饱和物理机制进行了细致数值模拟研究。研究结果表明:二次电子数目、放电电流、放电功率、沉积功率随时间以指数形式快速增长后趋于饱和波动或振荡。随着间隙电压幅值的增加,二次电子数目、放电电流、放电功率、沉积功率均呈现先增加后减小的规律。放电电流波形相对间隙射频电压波形存在延时现象,导致二次电子倍增中存在部分充电过程;随着间隙电压幅值的增加,延时逐步缩短,二次电子倍增逐步转化为稳定放电状态。二次电子倍增发展阶段,射频相位聚焦效应占主导;二次电子倍增过程中存在明显的电子束宽度拓宽现象,当空间电荷效应与射频场对电子的相位聚焦效应平衡时,二次电子倍增进入饱和阶段。二次电子倍增过程中空间电荷场主要起到了两方面作用。首先,空间电荷效应导致电子碰撞相位发散,使电子溢出聚焦相位区间;其次,空间电荷效应导致发射面电场呈现"反场"效应直接阻止了二次电子的发射。更多还原

【Abstract】 Based on the two-surface multipactor theoretical analysis and susceptibility curves evaluation, a 1D3V(one dimensional and velocity with three directions) PIC-MC(Particle in Cell and Monte Carlo) method is built to investigate the transient evolution and saturation characteristics of oxygen-free copper two-surface multipactor discharge numerically. During multipactor discharge, the number of secondary electrons, the discharge current, the discharge power and the deposited power increase exponentially and tend to be steady with fluctuation or oscillation. With the increase of the amplitude of gap RF voltage, the number of secondary electrons, the discharge current, the discharge power and the deposited power increase and then decrease. There is a time-delay phenomenon in multipactor discharge especially in the saturation stage induced by space charge effects, the discharge current waveform is later than the gap RF voltage waveform. There is a charging-course during multipactor discharge caused by time-delay effect. With the increase of gap RF voltage amplitude, the time-delay effect tends to be weak, and the charging course tends to disappear. In the multipactor developing stage, the RF phase focusing effects are dominant. When the space charge effects balance the RF phase focusing effects, the multipactor saturation is coming. There is an obvious bunch expanding of electrons during multipactor discharge. The space charge effects play an important part in two ways. First, the mutual repulsion causes impact phases to spill over in the unfavorable phase where RF field is retarding. Second, the collective and strong space charge field opposing emission near the surface overcomes the RF field and limits emission even for a favora ble RF phase.更多还原