测量数MA脉冲电流的探头设计与标定

Design and calibration of B-dot monitor for several mega-ampere current measurement

为获得聚龙一号装置负载区电流,设计了测量探头,通过频响测试得到探头的频率上限为51.7MHz;针对标定装置的逼真性进行了分析,实验结果表明,负载区电流探头的灵敏度在误差范围内不受柱孔盘旋面的影响。通过标定结果的外推分析可知:外推是否可靠是由探头能否满足相应测量的工作条件决定,而不是受外推的数量级限制。通过探头测量范围的分析及相应干扰实验,认为标定满足测试需求。实测结果表明负载区电流与磁绝缘传输线电流的测量结果自洽。

Differential output current loops （B dot probes） were designed and calibrated to derive inner MITL current in the PTS facility. The B dots＇ upper limiting frequency was 51.7 MHz in frequency response experiments, which was satisfactory for current measurement in our experiments. The Bdots were calibrated using a radial transmission line that was driven by an azi muthally symmetric current pulse. And then the Bdots were calibrated using a radial transmission line with a post hole convolute feeding structure. The result indicates that the sensitivity of B dots are consistent in the two calibration systems. The interference test and experiments with variable peak currents were performed to focus on B dot linearity, and insulation, pressure exerted by magnetic fields, energy absorbing and related temperature rise of B dot were analyzed in order to assess the validity of Bdot cali bration. The results imply that the B dots are valid for several mega ampere current measurements. Also, it shows that outer MITL current and inner MITL current are self consistent in PTS experiment.