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Efficiency of particle acceleration at oblique strong CME shocks from 0.13 to 2.5 AU: PATH modeling

Authors :
Gary P. Zank
Xianzhi Ao
Gang Li
Olga Verkhoglyadova
Source :
AIP Conference Proceedings.
Publication Year :
2012
Publisher :
AIP, 2012.

Abstract

We compare the efficiency of proton acceleration at oblique strong CME shocks at radial heliocentric distances from 0.13 to 2.5 AU. We use the PATH code to obtain the diffusion coefficients and maximum achievable particle energies at shocks with 15°, 45° and 75° shock angles. In computing the maximum energy, we use the total diffusion coefficient which is a function of the parallel diffusion coefficient and the perpendicular diffusion coefficient. The parallel diffusion coefficient is calculated from the wave intensity of Alfven waves generated by streaming protons in the shock vicinity [1, 2]. The perpendicular diffusion is described in the NLGC approach and depends on the parallel diffusion coefficient and pre-existing turbulence in the solar wind [3, 4, 6]. It is shown that efficiency of particle acceleration at a fast CME-driven shock depends on the shock angle, injection energy and radial heliocentric distance. Quasi-perpendicular strong shocks are more efficient in accelerating higher-energy seed particles, especially at larger heliocentric distances and close to the Sun. By contrast, quasi-parallel strong shocks can accelerate particles more efficiently at distances about 1 AU.

Details

ISSN :
0094243X
Database :
OpenAIRE
Journal :
AIP Conference Proceedings
Accession number :
edsair.doi...........18f4eb3befd3a6a503487a63936e03ea
Full Text :
https://doi.org/10.1063/1.4768759