【摘要】 太阳硬Ｘ射线是耀斑高能电子束流与太阳大气相互作用产生的韧致辐射，根据简单的太阳耀斑环物理模型，假定具有流量与能谱同步变化的高能电子束流从耀斑环顶部注入，计算了硬Ｘ射线辐射在不同的靶物质密度区的能谱演变特征．结果表明：硬Ｘ射线辐射在低大气密度靶区呈现软一硬一硬的能谱演变特征，在高密度靶区硬Ｘ射线能谱则具有软一硬一软的变化特征．高能电子束流持续时间影响谱型转变区域在耀斑环中的高度．更多还原

【Abstract】 The hard X-rays of solar flares are produced by Bremsstrahlung interaction ofhigh energy electron beam impinging on solar atmosphere. Based on a simple physical model of flare loop, and under the assumption that the high energy electronswith synchronous variation between the beam flux and spectrum index are injectedfrom the top of the loop, some calculated results about hard X-ray spectrum evolution with different atmosphere density are obtained in this paper. These resultsshow: in low density area, such as in the top of loop, the hard X-ray spectrum hassoft-hard--hard evolution property, in high density area, such as in the foot points ofloop, the spectrum possesses soft--hard--soft variation. The time duration of injectingelectrons will influence the height of region in the loop where the one type of hardX-ray spectrum evolution will transform into the other one.更多还原