Power conversion factor in solar flares  

作　　者：NING ZongJun 

机构地区：[1]Key Laboratory of Dark Matter and Space Astronomy,Chinese Academy of Sciences,Nanjing 210008,China [2]Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210008,China

出　　处：《Chinese Science Bulletin》2012年第12期1397-1404,共8页

基　　金：supported by the National Natural Science Foundation of China(10833007,10973042,11073058,11073006,40804034);National Basic Research Program of China(2011CB811400);Key Laboratory of Dark Matter and Space Astronomy,Chinese Academy of Sciences(2010DP173032)

摘　　要：With RHESSI data from five solar flares taken from beginning to end,we investigate the power conversion factorμdefined as the ratio of the time derivative of total thermal energy(ERHESSI+Erad+Econd)and the kinetic power(PRHESSI)of nonthermal electrons.Here, ERHESSI is the computed energy contained in thermal plasmas traced by RHESSI SXRs.Other two contributions(Erad and Econd)to the total energy are the energies lost through radiation and conduction,both of which can be derived from the observational data.If both are not considered,μis only positive before the SXR maximum.However,we find that for each flare studiedμis positive over the whole duration of the soalr flare after taking into account both radiation and conduction.Mean values forμrange from 11.7% to 34.6%for these five events,indicating roughly that about this fraction of the known energy in nonthermal electrons is efficiently transformed into thermal energy from start to end.This fraction is traced by RHESSI SXR observations;the rest is lost.The bulk of the nonthermal energy could heat the plasma low in the atmosphere to drive mass flows(i.e.chromospheric evaporation).With RHESSI data from five solar flares taken from beginning to end, we investigate the power conversion factor kt defined as the ratio of the time derivative of total thermal energy （ERHESSI ＋ Erad ＋ Econd） and the kinetic power （PRHESSI） of nonthermal electrons. Here, EmaESSi is the computed energy contained in thermal plasmas traced by RHESSI SXRs. Other two contributions （Erad and Econd） to the total energy are the energies lost through radiation and conduction, both of which can be derived from the observational data. If both are not considered,/l is only positive before the SXR maximum. However, we find that for each flare studied μ is positive over the whole duration of the soalr flare after taking into account both radiation and conduction. Mean values for μ range from 11.7% to 34.6% for these five events, indicating roughly that about this fraction of the known energy in nonthermal electrons is efficiently transformed into thermal energy from start to end. This fraction is traced by RHESSI SXR observations; the rest is lost. The bulk of the nonthermal energy could heat the plasma low in the atmosphere to drive mass flows （i.e. chromospheric evaporation）.

关 键 词：太阳耀斑 转换因子 电源 热等离子体 总能量 转换系数 时间导数 非热电子 

分 类 号：P182.52[天文地球—天文学]