论文标题
通过在不均匀气氛中减速流板来产生失控的电子
Runaway Electron Generation by Decelerating Streamers in Inhomogeneous Atmosphere
论文作者
论文摘要
在大气压空气中，在数值上模拟了正流和负流的动力学。结果表明，在减速和停止时，正和负流媒体以根本不同的方式行事。当头电势下降时，负流元素将转移到传播是由于正向电子漂移引起的模式。在这种情况下，电离波前部的半径增加，而彩带头部的电场进一步降低，流弹片停止。正向流板降低头电位的唯一进步机制是电离波的有效半径降低，导致电场的局部增加。这种机制补偿了小头直径下气体光电离的效率的降低。当头部电势在大气压空气中降低到约1.2 kV时，彩带头的局部电场可能会超过失控的阈值。在这种情况下，可能会发生脉冲的一束失控的电子束，该束被引导到停止正面流媒体的通道中。形成的脉冲电子束的能量可以从700 V（相对于大气压空气的值增加10倍）到2.6 kV（在带有吸收添加剂的空气中，光电离电速率降低1000倍）。减速阳性流媒体的这种行为可能可以解释彩带传播过程中观察到的X射线辐射的突发。
The dynamics of positive and negative streamers is numerically simulated in atmospheric pressure air. It is shown that positive and negative streamers behave in radically different ways when decelerating and stopping. When the head potential drops, the negative streamer transits to the mode in which the propagation is due to the forward electron drift. In this case, the radius of the ionization wave front increases, whereas the electric field at the streamer head decreases further and the streamer stops. The only advancement mechanism for a positive streamer with decreasing head potential is a decrease in the effective radius of the ionization wave, leading to a local increase in the electric field. This mechanism compensates for the decrease in the efficiency of gas photoionization at small head diameters. The local electric field at the streamer head can exceed the runaway threshold when the head potential decreases to ~1.2 kV in atmospheric pressure air. In this case, pulsed generation of a beam of runaway electrons directed into the channel of a stopping positive streamer can occur. The energy of the formed pulsed electron beam can vary from 700 V (when increasing the photoionization rate by a factor of 10 with respect to the value in atmospheric pressure air) to 2.6 kV (in air with an absorbing additive that reduces the photoionization rate by a factor of 1000). It is possible that this behavior of decelerating positive streamers can explain the observed bursts of X-ray radiation during the streamer propagation.
