Modelling the Exposure of Satellites in Medium Earth Orbit to Proton Belt Radiation
type: CreativeWork
description: Geomagnetically trapped protons forming Earth's proton radiation belt pose a hazard to orbiting spacecraft. In particular, solar cells are prone to degradation caused by non-ionising collisions with protons in the energy range of several megaelectron volts, which can ultimately shorten the lifespan of a mission. Dynamic enhancements in trapped proton flux following solar energetic particle events have been observed to last several months, and there is a strong need for physics‐based modelling in order to predict the impact these changes may have on orbiting spacecraft. This thesis addresses the need for physics-based modelling by presenting an investigation into inner proton belt variability with a 3D numerical model created from scratch, and by quantifying the impact that variability has on the solar cell degradation of orbiting satellites. After a review of background concepts in Chapter 1, Chapter 2 presents a case study on satellites undergoing electric orbit raising to geostationary orbit. The increase in solar cell degradation that can occur during a period of proton belt enhancement is calculated for three example orbits. It is found that a large enhancement can cause an additional degradation in solar cell output power by up to ~5% over the course of orbit raising, and further changes of a few percent are shown to occur based on the choice of trajectory, or for a 50μm change in solar cell coverglass shielding thickness. In Chapter 3 a physics-based numerical model is constructed, solving for proton phase space density in terms of the first, second and third adiabatic invariants μ, K and L. This chapter demonstrates how key processes can be quantified, including transport via radial diffusion, the cosmic ray albedo neutron decay source and coulomb collisional loss. In Chapter 4, a 2D version of the model is applied to derive proton radial diffusion coefficients for a period of solar maximum. This is achieved by varying parameters controlling the rate of radia…
abstract: Geomagnetically trapped protons forming Earth's proton radiation belt pose a hazard to orbiting spacecraft. In particular, solar cells are prone to degradation caused by non-ionising collisions with protons in the energy range of several megaelectron volts, which can ultimately shorten the lifespan of a mission. Dynamic enhancements in trapped proton flux following solar energetic particle events have been observed to last several months, and there is a strong need for physics‐based modelling in order to predict the impact these changes may have on orbiting spacecraft. This thesis addresses the need for physics-based modelling by presenting an investigation into inner proton belt variability with a 3D numerical model created from scratch, and by quantifying the impact that variability has on the solar cell degradation of orbiting satellites. After a review of background concepts in Chapter 1, Chapter 2 presents a case study on satellites undergoing electric orbit raising to geostationary orbit. The increase in solar cell degradation that can occur during a period of proton belt enhancement is calculated for three example orbits. It is found that a large enhancement can cause an additional degradation in solar cell output power by up to ~5% over the course of orbit raising, and further changes of a few percent are shown to occur based on the choice of trajectory, or for a 50μm change in solar cell coverglass shielding thickness. In Chapter 3 a physics-based numerical model is constructed, solving for proton phase space density in terms of the first, second and third adiabatic invariants μ, K and L. This chapter demonstrates how key processes can be quantified, including transport via radial diffusion, the cosmic ray albedo neutron decay source and coulomb collisional loss. In Chapter 4, a 2D version of the model is applied to derive proton radial diffusion coefficients for a period of solar maximum. This is achieved by varying parameters controlling the rate of radia…
author: Lozinski, Alexander
language: eng
keywords: radiation belts, proton belt, satellites, space solar cells, non-ionising damage
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2021-09-28
date modified: 2026-07-22T22:24:04Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.81958