This was one of a set of three sketches, showing the 1962 level of understanding of how to interpret the solar flare microwave sources. Here the type III electron streams are seen going down, to produce hard X-rays - this had been originally suggested by De Jager, I think, based on the skimpiest possible observational material. This was prior even to OSO-1! The idea of skinny magnetic flux tubes guiding the electrons in the low corona perhaps had not quite sunk in. These were the early days of plasma astrophysics; note the title of the paper (nowadays we don't think of "interplanetary gas" so much).. De Jager's later cartoon got more deeply into what happens as the electrons stream into the chromosphere, in the thick-target picture.
16 April 2008