Z箍缩内爆产生的电磁脉冲辐射

Electromagnetic pulse emission produced by Z pinch implosions

讨论了Z箍缩内爆产生的低频电磁脉冲的辐射特性.Z箍缩驱动金属丝阵或固体套筒高速内爆,部分磁能通过与负载的运动耦合而向外辐射.理论结果表明,电磁脉冲辐射功率由电流和内爆轨迹共同决定.在中国工程物理研究院流体物理研究所的初级实验平台上开展了负载电流为7 MA,10%—90%上升时间65 ns的丝阵Z箍缩实验,根据实验测得的电流和内爆轨迹得到了电磁脉冲的辐射功率和频谱.电磁脉冲峰值功率约为1 GW,能量约为0.5 J,能量转换效率约为10 7;峰值频率位于20—70 MHz,具有较宽的辐射频谱.电磁脉冲辐射参数远小于软X射线辐射参数(峰值功率为50 TW,能量为0.5 MJ).在弱相对论条件下,电磁脉冲辐射功率近似地正比于电流的6次方,随电流急剧增大.软X射线辐射是丝阵Z箍缩过程中的主要能量转换形式,本文的研究结论表明,在更高的驱动电流下,电磁脉冲辐射将提供另一种重要的能量转换途径,势必会对诊断设备造成严重影响;此外,这类强电磁脉冲在其他领域也具有潜在的应用价值.

In this paper, we represent the radiation characteristics of electromagnetic pulse generated by Z pinch implosion. Magnetic energy which couples with motions of metallic wire arrays or solid liners driven by Z pinch can radiate away. Theoretical results indicate that the radiation power of electromagnetic pulse is determined by both load current and implosion trace. Experiments are carried on primary test stand facility at Institute of Fluid Physics where a current rising to 7 MA in（10%–90%） 65 ns is used to drive a wire array Z pinch. The measured load current and implosion trace show that the Z pinch can deliver about 1 GW, 10 ns full width, 20–70 MHz central frequency, broadband electromagnetic pulse with an energy conversion efficiency of 10 7. Parameters of electromagnetic pulse are much smaller than those of X-ray with a power of 50 TW and an energy of 0.5 MJ. In the approximation of weak relativistic case, the power of electromagnetic pulse which is proportional to sixth power of load current, dramatically increases with current increasing. Soft X-ray radiation is an important channel for dissipating a considerable fraction of energy provided by facility. The results presented here demonstrate that electromagnetic pulse emission in the case of higher load current can cause significant damage to diagnostic devices. Moreover, intense electromagnetic pulse produced by this method may have many potential applications.