Impulsive Hard X-Ray and Ultraviolet Emission during Solar Flares
Kane, S. R. and R. F. Donnelly, Impulsive Hard X-Ray and Ultraviolet Emission during Solar Flares, ApJ, 164, 151 (1971) (ADS)
(click on the image for a larger version)
This cartoon captures the basic observational underpinning of the
thick-target model, which envisions an
electron beam penetrating the
lower solar atmosphere from a black box in the corona.
This paper reflected the interpretation of flare effects on the ionosphere by
Dick Donnelly [1]; this link cemented the energetic significance of the non-thermal electrons that
produce the impulsive flare hard X-rays.
The paper thus also clearly presented the world with the "number problem" and the
vexing issue of how to imagine that magnetic reconnection somehow - in a
fluid approximation - put most of the flare energy into a non-thermal particle flux.
Note that the geometry of the hard X-ray source is misconstrued here,
but that the close association with partial ionization and EUV
emission gets clear recognition.
This cartoon captures the basic observational underpinning of the thick-target model, which envisions an electron beam penetrating the lower solar atmosphere from a black box in the corona. This paper reflected the interpretation of flare effects on the ionosphere by Dick Donnelly [1]; this link cemented the energetic significance of the non-thermal electrons that produce the impulsive flare hard X-rays. The paper thus also clearly presented the world with the "number problem" and the vexing issue of how to imagine that magnetic reconnection somehow - in a fluid approximation - put most of the flare energy into a non-thermal particle flux. Note that the geometry of the hard X-ray source is misconstrued here, but that the close association with partial ionization and EUV emission gets clear recognition.
[1] Donnelly