Reames, Donald V., Energetic Particles from Impulsive Solar Flares, The Astrophysical Journal Supplement Series, 73, 235 (1990) (ADS)
(click on the image for a larger version)
The work of Don Reames has been fundamental in distinguishing
"impulsive" solar particle (SEP) events (SPEs) from "gradual" ones,
with the latter strongly identified with the coronal and interplanetary
shock waves known (e.g., via geomagnetic effects) to be associated
with flares and coronal mass ejections.
The shock mechanism,
whether the whole story or not, has a
well-developed theoretical literature.
This does not seem to be the case for the particle
acceleration associated with impulsive SEPs, and this cartoon was
a pioneering effort to understand the configuration in the low
corona.
What this cartoon calls "E. M. Waves" might instead be
described as MHD waves associated with magnetic restructuring?
If not, this just reveals the low level of the state of the art in
1990, not much improved at present.
How do the ill-understood flux tubes guide the particles
from the lowest corona into the distant heliosphere?
But no, here is the non-MHD idea, as shown in the earlier
Sprangle-Vlahos cartoon
argues that electron cyclotron waves can couple the flare volume
with the open flux tube.
To the Archivist's mind, this seems a lot
more attractive than an MHD reconnection model, which would involve
singular surfaces and not full 3D volumes - we know observationally
that the open flux tubes expand broadly into space, and do not
behave like essentially 2D sheets.
The work of Don Reames has been fundamental in distinguishing "impulsive" solar particle (SEP) events (SPEs) from "gradual" ones, with the latter strongly identified with the coronal and interplanetary shock waves known (e.g., via geomagnetic effects) to be associated with flares and coronal mass ejections. The shock mechanism, whether the whole story or not, has a well-developed theoretical literature. This does not seem to be the case for the particle acceleration associated with impulsive SEPs, and this cartoon was a pioneering effort to understand the configuration in the low corona. What this cartoon calls "E. M. Waves" might instead be described as MHD waves associated with magnetic restructuring? If not, this just reveals the low level of the state of the art in 1990, not much improved at present. How do the ill-understood flux tubes guide the particles from the lowest corona into the distant heliosphere?
But no, here is the non-MHD idea, as shown in the earlier Sprangle-Vlahos cartoon argues that electron cyclotron waves can couple the flare volume with the open flux tube. To the Archivist's mind, this seems a lot more attractive than an MHD reconnection model, which would involve singular surfaces and not full 3D volumes - we know observationally that the open flux tubes expand broadly into space, and do not behave like essentially 2D sheets.