Carlqvist, P., A flare-associated mechanism for solar surges., Sol. Phys., 63, 353-367 (1979) (ADS)
(click on the image for a larger version)
Electrostatic double layers can form within current filaments flowing
in a dynamic plasma. This is the original basis of the
Alfvén-Carlqvist
flare model, which sought to explain flare energy release as a current
interruption.
In the magnetosphere one frequently observes double
layers associated with the aurora and its current system, and so
it seems eminently plausible to consider them in the solar corona
as well.
This cartoon fleshes out the electrodynamics of such a
phenomenon, noting that the charge separation in the current-carrying
filament results in a radial electric field at its boundary, ie an
electric field perpendicular to the axis of the filament.
The paper discusses the complexities of the electrodynamics resulting from
the occurrence of the double layer, and applies it to the creation of a surge
(this is one form of solar eruption as observed in Hα; in these latter
days, armed with soft X-rays, we pay more attention to the probably related
jet phenomenon.
The Canfield surge cartoon notes the
presence of twist, which a current-carrying filament would exhibit, and the
connection to "open" fields, which the observations require.
Note that this cartoon places the double layer at loop top; perhaps the paper
explains why this might make sense.
In the case of the terrestrial aurora, observations show such plasma structures
in the legs, rather than the point of symmetry.
Electrostatic double layers can form within current filaments flowing in a dynamic plasma. This is the original basis of the Alfvén-Carlqvist flare model, which sought to explain flare energy release as a current interruption. In the magnetosphere one frequently observes double layers associated with the aurora and its current system, and so it seems eminently plausible to consider them in the solar corona as well. This cartoon fleshes out the electrodynamics of such a phenomenon, noting that the charge separation in the current-carrying filament results in a radial electric field at its boundary, ie an electric field perpendicular to the axis of the filament.
The paper discusses the complexities of the electrodynamics resulting from the occurrence of the double layer, and applies it to the creation of a surge (this is one form of solar eruption as observed in Hα; in these latter days, armed with soft X-rays, we pay more attention to the probably related jet phenomenon. The Canfield surge cartoon notes the presence of twist, which a current-carrying filament would exhibit, and the connection to "open" fields, which the observations require.
Note that this cartoon places the double layer at loop top; perhaps the paper explains why this might make sense. In the case of the terrestrial aurora, observations show such plasma structures in the legs, rather than the point of symmetry.