Modelling the acceleration and transport of energetic particles in a corotating interaction region
Abstract
Spacecraft equipped with particle detectors will occasionally measure enhanced levels of energetic ions in the vicinity of corotating interaction regions (CIRs). These ions can have energies up to ${\sim}$20 MeV/nuc and are believed to result from interplanetary acceleration processes for which the supra-thermal tail of the solar wind may constitute the seed population. Conceivable acceleration mechanisms of these ions include compressional or diffusive shock acceleration, which can happen in the forward and reverse compression/shock waves bounding the CIR. Once accelerated, these ions may stream away from the CIR, and can therefore sometimes be detected in, for example, the fast solar wind stream trailing the CIR. In this work we present the results of a modelling effort aimed at increasing our understanding of the transport and acceleration of supra-thermal ions in the vicinity of CIRs. This is accomplished by using the three-dimensional particle transport model PARADISE, which solves the focused transport equation by propagating pseudo-particles in a solar wind generated by the three-dimensional magnetohydrodynamic model EUHFORIA. The latter model is used to generate a solar wind containing a CIR, in which we subsequently inject ions of ${\sim}$10 keV/n at a continuous rate. We study the particle acceleration efficiency of both the reverse and forward CIR compression/shock waves, by considering different particle scattering conditions. In addition, we investigate how the magnetic topology near and within the CIR affects the transport of the accelerated ions into the inner heliosphere, up to heliocentric radial distances visited by Parker Solar Probe.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E1070A