HR: 1330h
AN: SH22A-0179    [PDF]
TI: Density Structure in a Pre-Eruption Coronal Flux Loop
AU: * Krall, J
EM: krall@ppdmail.nrl.navy.mil
AF: Plasma Physics Division, Naval Research Lab., Code 6794 4555 Overlook Ave., SW, Washington, DC 20375-5346 United States
AU: Chen, J
EM: chen@ppdmail.nrl.navy.mil
AF: Plasma Physics Division, Naval Research Lab., Code 6794 4555 Overlook Ave., SW, Washington, DC 20375-5346 United States
AB: A density model is developed for a coronal loop, extending from the collisionless corona ($\nu_i \ll \Omega_i$) down to foot points in the highly-collisional chromosphere ($\nu_i \gg \Omega_i$), under the approximation that neighboring flux surfaces within the flux loop are ``non interacting''. This model, valid if the characteristic fluid-element speed is large enough ($v > v_c$), results in a density enhancement at the edge of the loop which is a function of its specified magnetic field. Here, $v_c$ is the critical fluid-element speed: for $v < v_c$, the number of collisions occurring during a single transit of the loop is large enough to diffuse away the density enhancement that exists in the limit of zero collisions in coronal segment of the loop. For solar parameters, $v_c \simeq 1$ km/s. It is shown that this model can explain the post-eruption density enhancement (the bright rim) observed in coronal mass ejections. This result is distinct from coronal loop models in which the fluid elements making up the plasma are assumed to be static and collisionally-coupled (such models have been used to address thermal properties, rather than the three-dimensional density structure, of coronal loops). Work supported by ONR and NASA.
DE: 7513 Coronal mass ejections
DE: 7524 Magnetic fields
DE: 7531 Prominence eruptions
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting