On the Detection of Coronal Suprathermal Ions and their Role as Seeds for SEP Production
Abstract
We review our understanding of the evolution of disturbances driven by coronal massejections (CMEs) as they move outward from the solar corona. In low beta plasma, a fast modeshock forms when the disturbance speed exceeds the local Alfven speed, and this shock becomessupercritical at an Alfven Mach number of between 1 and approximately 3, depending on obliquity. A population of pre-existing suprathermal particles can interact with the shock. Various authorshave considered these either as "seed" particles, of sufficient energy to be further acceleratedby shock processes, or as a population of drifting particles that can excite pre-shock Alfven wavesif their velocity distribution is sufficiently hard. Both features are necessary to initiate shockacceleration. A number of lines of evidence suggest that such acceleration must begin close to the sun,soon after the shock actually forms, and especially for large SEP events. The details of the pre-existingsuprathermal population then offer a means of understanding the variability in Solar Energetic Particle(SEP) events, wherein two ostensibly similar CMEs can have very different SEP characteristics, andpossibly a path to operational forecasts. We further discuss an observational technique designed to investigate this problem by detectingsuprathermal seed particles as extended wings on spectral lines, and describe an experimentdesigned for a flight opportunity on the DoD Space Test Program, due for launch in 2019.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSH51A2573L
- Keywords:
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- 2101 Coronal mass ejections;
- INTERPLANETARY PHYSICSDE: 2102 Corotating streams;
- INTERPLANETARY PHYSICSDE: 2139 Interplanetary shocks;
- INTERPLANETARY PHYSICSDE: 2788 Magnetic storms and substorms;
- MAGNETOSPHERIC PHYSICS