Generation of runaway electrons induced by radon progeny products in thunderstorm electric fields and the initiation of lightning discharges

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徐 陽

Yang, X.

雷活動時の線量上昇の原因を明らかにするために、モンテカルロ計算による放射線挙動を解析した。本件では、ラドン子孫核種を線源とした場合の解析結果について報告する。その結果、Rn子孫核種では光子(線)束の有意な変動は見られないが、電子束の急激な上昇が示された。このため、Rnは線量上昇には寄与しないものの、電子密度の増加から雷放電に寄与している可能性が考えられた。本稿は、自然放射線関係の国際会議のプロシーディングス用原稿である。

ray dose-rate increases associated with winter thunderstorm activities have been observed in the coastal areas facing the Sea of Japan. In order to investigate the generation of energetic photons which originate in thunderstorm electric fields, we have calculated the behaviour of electrons and photons in electric fields with Monte Carlo method. In case of the calculation for the energetic electron emitted in the atmosphere, the electron and photon fluxes have increased greatly in the region with a strong electric field. Then, we have carried out the Monte Carlo transport calculations of the beta and rays emitted by radon progeny products, as a source of energetic electrons, in thunderstorm electric fields. From the calculated results, it is confirmed that the electron flux shows notable increases in the strong electric field, while the photon flux does not fluctuate significantly.