Radiation Bursts Synchronizing with Lightning Discharges in Hokuriku,Japan
Recent studies have suggested radiation bursts on the ground are related to lightning activities.We believe these phenomena as a result of runaway breakdown (RB).In RB theory,high energy electrons of secondary cosmic rays are accelerated with radiating photons in the high electric field strength in a thundercloud. These electrons and photons make avalanches and trigger lightning discharges.To detect energetic radiation efficiently,it is necessary to conduct observation campaigns where the lightning discharge occurs at low attitude. That is why we conducted lightning observation campaigns in Hokuriku,Japan,the coastal area of the Sea of Japan,during winter thunderstorm season to get further understanding of the relationship between the lightning discharges and radiation bursts.Our observation system consists of main four detectors,high energy electron detector,radiation detector,a slow antenna,and Rogowski coils.The high energy electron detector has a plastic scintillator whose response ratio of high energy electrons to photons is quite high.The radiation detector has an NaI scintillator designed for detecting high energy photons.The two bursts of both high energy electron and photon radiation were observed in synchronization with the cloud-to-ground (CG)lightning flashes striking a wind turbine or a lightning protection tower near the observation site.The strength of the photon radiation detected on the ground was inversely proportional to the distance between the tip of the negative stepped leader and the observation site.Furthermore,the photon and high energy electron bursts were recorded as the tips of the negative leaders came closer to the positively charged region.These results indicate that 1)RRB occurred at the tip of the negative stepped leader,and 2)the last phase of the stepped leader causes more energetic RRB.
S.Yoshida M.Satoh T.Morimoto T.Ushio Z.Kawasaki T.Torii D.Wang N.Takagi T.Watanabe
Graduate School of Engineering,Osaka University,Osaka,Japan Tsuruga Head Office,Japan Atomic Energy Agency,Tsuruga,Japan Graduate School of Engineering,Gifu University,Gifu,Japan
国际会议
第13届国际大气电学会议(The 13th International Conference on Atmospheric Electricity)
北京
英文
2007-08-13（万方平台首次上网日期，不代表论文的发表时间）