真空磁绝缘线B-dot电流探测器的研制

为了测量阳加速器新真空磁绝缘线的电流,研制并标定了B-dot探测器。2个B-dot的探测器分别安装在磁绝缘线的入口和中部,输出信号与被测电流的微分成正比,经RC积分后获得电流信号。B-dot探测器采用在线标定,当阴阳极短接点数量较少,且位置距离探测器较近时,会因真空绝缘线(MITL)电流密度不均匀导致标定不准确,故需增多短接点。当短接点的位置距离探测器约2m时,即使只设置2个连接点,探测器位置的MITL电流密度近似均匀。加速器实验结果表明:在MITL阴阳极较近的位置,将B-dot探头安装在阳极孔中不影响磁绝缘效果,B-dot探测器测试稳定可靠,其设计和标定方法可行。

Design of B-dot Monitor in Magnetically Insulated Transmission Line

A B-dot current monitor used for YANG accelerator's magnetically insulated transmission line(MITL)was designed.B-dot is a magnetic coupling loop that export the signal which is proportional to the time derivative of the current,and the signal of proportional current is obtained with the RC integrator.The B-dot was fixed in entrance and middle of MITL.The coupling loop was joined to a signal connector of airproofed vacuum.The loop was in a cavity of the MITL anode when distance from cathode to anode is near.The monitor was calibratedon line.A pulse was delivered from export of MITL.One or two short-circuit load was connected from cathode to anode in water transmission line.A Rogowski coil was mounted at the center of MITL to measure current.The current density of MITL is not uniformity when connector is near the B-dot monitor,leading to error of calibration.The experiment of calibration indicates that the current density is almost uniformity when the distance between connector and the B-dot monitor is about 2 meters.The experiment of MITL when accelerator shots to the short-circuit load was done.The position about the monitor is not imprinted by emission of electron,proving that the effect of magnetic insulation should not changed by monitor.The current of YANG accelerator's MITL is about 1 MA,and the rise time is less than 90 ns.