2020/11/15 by Andrey Starikovskiy, Starikovskiy, Andrey, N. L. Aleksandrov +3
Engineering · Medicine · Physics and Astronomy · #FOS: Physical sciences #Gyrotron and Vacuum Electronics Research #Plasma Applications and Diagnostics #Plasma Physics (physics.plasm-ph) #Pulsed Power Technology Applications
paper · pdf · doi:10.48550/arxiv.2011.07461
openalex publication_date 2020/11/15 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
The dynamics of positive and negative streamers is numerically simulated in\natmospheric pressure air. It is shown that positive and negative streamers\nbehave in radically different ways when decelerating and stopping. When the\nhead potential drops, the negative streamer transits to the mode in which the\npropagation is due to the forward electron drift. In this case, the radius of\nthe ionization wave front increases, whereas the electric field at the streamer\nhead decreases further and the streamer stops. The only advancement mechanism\nfor a positive streamer with decreasing head potential is a decrease in the\neffective radius of the ionization wave, leading to a local increase in the\nelectric field. This mechanism compensates for the decrease in the efficiency\nof gas photoionization at small head diameters. The local electric field at the\nstreamer head can exceed the runaway threshold when the head potential\ndecreases to ~1.2 kV in atmospheric pressure air. In this case, pulsed\ngeneration of a beam of runaway electrons directed into the channel of a\nstopping positive streamer can occur. The energy of the formed pulsed electron\nbeam can vary from 700 V (when increasing the photoionization rate by a factor\nof 10 with respect to the value in atmospheric pressure air) to 2.6 kV (in air\nwith an absorbing additive that reduces the photoionization rate by a factor of\n1000). It is possible that this behavior of decelerating positive streamers can\nexplain the observed bursts of X-ray radiation during the streamer propagation.\n