Dreicer Electric Field Definition and Runaway Electrons in Solar Flares  

作　　者：Yu.T.Tsap A.V.Stepanov Yu.G.Kopylova 

机构地区：[1]Crimean Astrophysical Observatory of the Russian Academy of Sciences,Nauchny,298409,Russia [2]Pulkovo Observatory of the Russian Academy of Sciences,Pulkovskoje Shosse,65/1,St.Petersburg,196140,Russia

出　　处：《Research in Astronomy and Astrophysics》2024年第2期180-184,共5页天文和天体物理学研究（英文版）

基　　金：supported by the Russian Foundation for Basic Research and the Czech Science Foundation(project No.20-52-26006,Tsap Yu.T.);the Russian Science Foundation(project No.22-12-00308,Stepanov A.V.and Tsap Yu.T.)。

摘　　要：We analyze electron acceleration by a large-scale electric field E in a collisional hydrogen plasma under the solar flare coronal conditions based on approaches proposed by Dreicer and Spitzer for the dynamic friction force of electrons.The Dreicer electric field EDr is determined as a critical electric field at which the entire electron population runs away.Two regimes of strong(E≲E_(Dr))and weak(E≪E_(Dr))electric field are discussed.It is shown that the commonly used formal definition of the Dreicer field leads to an overestimation of its value by about five times.The critical velocity at which the electrons of the"tail"of the Maxwell distribution become runaway under the action of the sub-Dreiser electric fields turns out to be underestimated by√3 times in some works because the Coulomb collisions between runaway and thermal electrons are not taken into account.The electron acceleration by sub-Dreicer electric fields generated in the solar corona faces difficulties.

关 键 词：acceleration of particles-Sun flares-Physical Data and Processes 

分 类 号：P182.52[天文地球—天文学]