SH41B-2777: The acceleration of particles at propagating interplanetary shocks

Enhancements of charged energetic particles are often observed at Earth following the eruption of coronal mass ejections (CMEs) on the Sun. These enhancements are thought to arise from the acceleration of those particles at interplanetary shocks forming ahead of CMEs, propagating into the heliosphere. In this study, we model the acceleration of these energetic particles by solving a set of stochastic differential equations formulated to describe their transport and including the effects of diffusive shock acceleration. The study focuses on how acceleration at halo-CME-driven shocks alter the energy spectra of non-thermal particles, while illustrating how this acceleration process depends on various shock and transport parameters. We finally attempt to establish the relative contributions of different seed populations of energetic particles in the inner heliosphere to observed intensities during selected acceleration events

SH41B-2761: Solar energetic particle transport and the possibility of wave generation by streaming electrons

After being accelerated close to the Sun, solar energetic particles (SEPs) are transported (mainly) along the turbulent interplanetary magnetic field. In this study, we simulate the propagation of ~100 keV electrons as they are scattered in the interplanetary medium. A consequence of these wave-particle interactions is the possible modification (either growth or damping) of the background turbulence by anisotropic SEP electron beams. This process was thought to be negligible, and therefore neglected in past modeling approaches. However, recent observations and modeling by Agueda and Lario (2016) suggest that wave generation may be significant and is therefore included and evaluated in our present model. Our results suggest that wave amplification by streaming SEP electrons is indeed possible and may even significantly alter the background turbulent field. However, the simulations show that this process is much too weak to produce observable effects at Earth’s orbit, but such effects may well be observed in future by spacecraft closer to the Sun, presenting an intriguing observational opportunity for either the Solar Orbiter or the Parker Solar Probe spacecraft. Lastly, we note that the level of perpendicular diffusion may also play an important role in determining the effectiveness of the wave growth process.<p>Reference: Agueda, N. and Lario, D. Release History and Transport Parameters of Relativistic Solar Electrons Inferred From Near-the-Sun In Situ Observations, ApJ, 829, 131, 2016.</p

Development of the HARM model for aviation dosimetry

 Primary galactic cosmic-rays (GCRs) and Solar energetic particles (SEPs) enter the Earth's atmosphere in varying amounts. Due to that, the aircrew and passengers are exposed to ionizing radiation in amounts that depend on severable factors. At the top of the atmosphere and beyond, cosmic radiation is modulated by the geomagnetic field and solar activity. Once ionising radiation, albeit from either GCRs or SEPs, crosses the geomagnetic field and enters the atmosphere, it interacts with the atmospheric molecules in the same manner regardless of where it came from. The High Altitude Radiation Monitor (HARM) model has been in development at the North-West University since January 2021, for calculation of doses of ionizing radiation in the atmosphere. Here we introduce this model, discuss its input parameters and output results, and show its initial results during flights compared with other well known models.</p