天鹅绒阴极脉冲放气及重复频率运行真空特性  

Outgassing characteristics of velvet cathode under single and repetition rate pulse operation

作　　者：荀涛[1] 杨汉武[1] 张建德[1] 张自成[1] 樊玉伟[1] 

机构地区：[1]国防科学技术大学光电科学与工程学院,长沙410073

出　　处：《强激光与粒子束》2010年第3期595-599,共5页High Power Laser and Particle Beams

基　　金：国家高技术发展计划项目

摘　　要：为获得天鹅绒阴极加电运行时的放气信息，在加速器Torch-02（电压约300kV、脉宽约6ns、电阻约100Q、频率1～300Hz）上开展了单次及重复频率下的真空兼容性实验研究。对于发射面积为28cm^2、阴阳极间距50mm、有效抽速62L／s、容积为4．6L的真空二极管-天鹅绒阴极系统，根据不同电流发射密度时的气压历史曲线，确定了单位面积上天鹅绒表面中性气体释放数目与脉冲能量的关系。通过实时记录不同频率下的气压演化，在本底气压约5×10^-3Pa、单脉冲能量约6J条件下，得到了平衡压强与重复频率的变化关系：10～100Hz时，平衡压强与重复频率近似呈线性递增；超过100Hz时，真空恶化明显，气压随频率呈超线性增长，300Hz时平衡压强已升至Pa量级。最后，针对重复频率运行时的放气特点，讨论了一种“分布式”抽气思想以改善系统有效抽速。Outgassing characteristics of a polymer velvet cathode under single shot and repetition rate （rep-rate） operation were experimemally investigated on a pulser, Torch-02, which has an about 300 kV, adout 6 ns and 1 to 300 Hz rep-rate output. For a 10 L vacuum diode-velvet cathode system with an emission area of 28 cm^2 , an A-K gap of 50 mm and an effective pumping speed of 62 L/s, the pulse desorption profiles with different emitting current densities were obtained. According to the pressure histories, the dependence of equilibrium pressure on pulse rep-rate was presented in the condition of about 5 × 10^-3 Pa base pressure and about 6 J single pulse energy. The diode pressure for burst mode test increased almost linearly with pulse rep-rate from 10 to 100 Hz, and increased hyper-linearly with pulse rep-rate above 100 Hz, exceeding 1 Pa for 300 Hz. Besides, a distributed pumping idea was discussed to improve the transient pumping ability for a velvet cathode operated in rep-rate mode.

关 键 词：天鹅绒 脉冲放气 重复频率运行 平衡压强 真空二极管 

分 类 号：TL503[核科学技术—核技术及应用]