Optical, hard x-ray, and microwave emission during the impulsive phase of flares

A study was made of the variation in hard (E greater than or equal to 10 keV) x-radiation, H-alpha, and microwave emission during the impulsive phase of solar flares. Most important, the observations showed that there is an optical impulsive component in addition to the well-known hard x-ray and microwave spikes discussed by Kane and Anderson (1970). Properties of these Hα kernels are given. Further analysis shows that the rise time in the 20- to 32-keV x-ray spike depends on the slope in the electron spectrum. E/sup -delta/ as t/sub rise/ = 0.11 exp (0.87)delta when thick target theory is used. A picture of the impulsive phase is given that is consistent with observations of the three above emissions. (U.S.)