为了提高装置容许的运行电压以提高辐射剂量产额,开展了放电过程中影响脉冲形成网络过电压幅值因素的研究。在引入开关导通不同步性和导通电阻条件下,建立了适用于任意电阻性负载的级联Blumlein型脉冲形成网络电压波过程理论模型,基于波过程模型进一步分析了影响脉冲形成网络过电压幅值的因素。研究表明开关不同步是产生过电压的主要因素,过电压峰值出现在开关闭合后的3倍形成网络电长度时刻。随着网络级联级数的增加,二极管阻抗与源阻抗匹配情况下最大过电压可达到-2倍充电电压,而二极管阻抗下降使得过电压幅值得以加强,阻抗过早崩溃可使过电压幅值接近充电电压的-3倍。

Stacked Blumlein pulse forming networks (PFNs) with photoconductive semiconductor switches can be used to drive flash X-ray diodes. In order to increase allowable running voltage of the device, factors affecting overvoltage on ceramic capacitors for PFNs during discharge are investigated. A voltage wave model of the stacked Blumlein PFNs is established, which incorporates parameters such as switch turn-on delay time, conductive resistance, and arbitrary resistor load, and the results are in accordance with that of PSpice circuit program. Moreover, factors influencing overvoltage coefficient are discussed, which shows that switch synchronization is key to overvoltage, the decreasing of diode impedance enhances the overvoltage coefficient, and too early collapse of diode impedance boosts the overvoltage up to -3 times the charge voltage.