Honors Theses and Capstones

Date of Award

Spring 2018

Project Type

Senior Honors Thesis

College or School




Program or Major


Degree Name

Bachelor of Science

First Advisor

Benjamin Chandran

Second Advisor

Harald Kucharek


The Sun is both a resource and a danger. We must be able to predict or have forewarning of large solar flares and coronal mass ejections (CMEs) and their potential threats to astronauts, GPS, radio communications, and power grids. I have used the Energetic Particle Radiation Environment Module (EPREM) code, which is used by PREDICCS, UNH's radiation dosage predictions website, to model interstellar-pickup ions (PUIs). I add to the model by including a momentum-diffusion term which contributes to the change in the distribution as it evolves in time. Here, I investigate how the given model of momentum-diffusion affects the energetic PUI population (with velocity greater than the solar wind velocity). This analysis focuses on the power-law spectra of the suprathermal tail of the PUI distribution. When the velocity dependence of the diffusion coefficient is normalized to the local solar wind velocity, I have found little to no change in the spectra of the suprathermal ion tails when momentum-diffusion is included. When the velocity dependence of the diffusion coefficient is not normalized, hardening of the spectra of the suprathermal ion tail is observed. It is possible that the affect of momentum-diffusion and particle acceleration in CIR's are the source of the energetic seed particle population, which makes up the available particles to be accelerated by a shock. In order to understand these potentially dangerous seed particles, we hope to use new observations from Parker Solar Probe to determine the acceleration processes, such as momentum-diffusion, that yield the observed spectra.