Time: Wednesday, May 18, 16:00 pm
Venue: Room 413, Buil. 11th, YuQuan Campus
10-1 郭苓202205018
Title：
Coherent transition radiation generated at the streamer acts as a radiation source of lightning radio-frequency emission
Abstract：
Thunderstorms produce multiband radio-frequency (RF) radiations and high-energy radiations simultaneously. Recent researches found that these radiations are closely associated with the leader head and the streamer during the propagation of the stepped leader. However, the detailed radiation mechanisms are still not fully understood. Based on the theory of thermal runaway electrons generated at the streamer tip, this paper proposes transition radiation as an alternative physical mechanism for producing lightning radio signals. When relativistic runaway electrons pass through the interface between the streamer and air, part of the electrons’ self-field will turn into transition radiation. We estimated the characteristic parameters of the electron beam at the streamer tip by combining the detection data of the streamer and radiation during discharges and analyzed the coherent transition radiation (CTR). The calculation results show that the energy spectrum and radiation power of CTR generated in the streamer tip are consistent with some results of experimentally detected RF radiations. In addition, our model also predicts the presence of THz-band radiation with extremely narrow width during lightning. Combined with the bremsstrahlung theory on high-energy radiation, our model can help explain the simultaneously detected RF radiation emitted from the leader. This model is also of great guidance to the scientific prevention of lightning disasters and the research on the propagation and location of lightning.
