HR: 11:45h
AN: SH22B-06    [Abstracts]
TI: Hybrid simulations of anisotropic proton distributions in solar coronal holes
AU: Hollweg, J
EM: joe.hollweg@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall, Durham, NH 03824, United States
AU: * Markovskii, S
EM: sergei.markovskii@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall, Durham, NH 03824, United States
AU: Vasquez, B
EM: bernie.vasquez@unh.edu
AF: Space Science Center, University of New Hampshire, Morse Hall, Durham, NH 03824, United States
AB: The plasma in solar coronal holes is likely to be energized by the resonant damping of proton cyclotron waves. In this case, the protons can develop considerable temperature anisotropy in the region where the solar wind becomes collisionless. The temperature anisotropy can give us important information about the processes in the solar corona based on in situ observations. The extrapolation of the values of the anisotropy from one heliocentric distance to another is not necessarily a valid procedure because the plasma heating and expansion, which contribute to the anisotropy, may operate differently there. However, the observations suggest that the mean anisotropy in the fast wind as a function of the plasma beta obeys the same scaling law at different distances. This can provide a link between widely separated regions of the solar wind. We will carry out hybrid simulations to determine how the proton anisotropy is affected by the interplay of the proton energization (perhaps by more than one mechanism), plasma instabilities self-driven by the distribution, and the solar wind expansion. We will verify if the observed beta scaling can be reproduced in a numerical experiment for typical coronal hole parameters.
DE: 7511 Coronal holes
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting