设计了一套用于同轴多间隙气体开关导通起始时间诊断的光纤探针阵列测试系统，其由光纤阵列与多通道快响应光电转换仪两部分组成，系统同步时间小于1 ns。使用该套系统同时对100 kALTD模块所有并联支路的10只开关的放电过程进行了测试，获得了开关导通起始时间及模块的输出电流波形。实验结果表明：开关工作欠压比为85%时，时间抖动不超过6.9 ns，负载波形重复一致性较好；开关工作欠压比降至53%时，时间抖动急剧增加至117.7 ns，负载波形重复一致性显著恶化。同时将光纤测试系统获得的各个开关导通起始时间带入Pspice电路模型进行模拟反演，结果表明，模拟结果与实验得到的模块输出电流波形吻合较好，证明了测试系统的准确性。

An optical fiber array is designed for testing initial discharge time of coaxial multigap gas switch, it has less than 1 ns time consistency and consists of two parts: optical fiber probe array and multichannel photoelectric convertor. Based on a 100kALTD module which has 10 parallel discharge branches, discharge time jitter of all switches has been tested. Experimental results show that: As the ratio of charge voltage and operating voltage is 85%, the time jitter is less than 6.9 ns, load current waveform has well consistency; while the ratio falls to 53%, time jitter dramatically increases to 117.7 ns and load current waveform consistency is deteriorated significantly. Experimental data from optic fiber array are put into the Pspice circuit model for simulation, the results show that the simulation results and experimental ones have better consistency. It proves the accuracy of the diagnosis system and the correctness of the analysis.