Aachen PK 2003 – scientific programme
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P: Plasmaphysik
P 10: Poster II
P 10.40: Poster
Tuesday, March 18, 2003, 17:30–19:15, Foyer
Proton Acceleration at X-points in Solar Flares — •K G McClements1, A Thyagaraja1, B Hamilton2, and L Fletcher2 — 1EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK — 2Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
An explicitly energy-conserving full orbit code CUEBIT, developed originally to describe energetic particle effects in tokamaks [1], has been applied to the problem of proton acceleration in solar flares. The model fields are obtained from solutions of the linearised MHD equations for reconnecting modes at a magnetic X-point [2], with the additional ingredient of a longitudinal magnetic field component. To accelerate protons to the highest observed energies on flare timescales, it is necessary to invoke anomalous resistivity in the MHD solution. It is shown that the addition of a longitudinal field component greatly increases the efficiency of ion acceleration, essentially because it suppresses E×B drifts away from the vicinity of the X-point, where the reconnection electric field is largest. Using plasma parameters consistent with flare observations, we obtain proton distributions extending up to γ-ray-emitting energies (>1 MeV).
This work was supported by an EPSRC CASE studentship and the UK Dept. of Trade and Industry.
[1] Wilson, H.R., et al., Proc. 19th IAEA Fusion Energy Conf., Lyon, October 14-19, 2002, paper no. FT/1-5 (2002)
[2] Craig I.J.D, McClymont, A.N., Astrophys. J. 371, L41 (1991)