The Height Distribution of Hard X-Rays in Impulsive Solar Flares
Matsushita et al. (1992) used the Hard X-ray Telescope on board the Yohkoh satellite to image hard X-ray (HXR) emission in 100 impulsive flares, and found that low energy emission comes from higher in the corona than high energy emission. This confirmed observations by Takakura et al (1986) with the Hinotori imager. The HXR emission is thought to be bremsstrahlung of non-thermal electrons, but the observed heights are much greater than found in previous theoretical calculations. This led to speculation that a super-hot (< 108K) plasma was present in impulsive flare loop-tops. However, using a stochastic simulation of electron transport we show that the inferred height distribution can be explained by a non-thermal model.