A Numerical Modeling of Electrostatic Radiation Shields

Abstract:

In the solar system, the most abundant electrically charged particles are low-energy, low-mass, low-charge, high-flux protons and electrons in the Solar Wind (SW), and high-energy, high-charge, high-mass, low-flux ions from both the Coronal Mass Ejections (CME) and the Solar Particle Events (SPE). In addition, outside the solar system, highly energetic particles that constantly bombard Earth are commonly denoted as Galactic Cosmic Rays (GCR). These consist of every element ranging from hydrogen (~89% of the GCR spectrum) to uranium (trace amounts) that is fully ionized (all electrons have been stripped from these atoms). These highly-charged energetic particles can be dangerous to our technologies and crew, say, astronauts traveling to the Moon and Mars. The adsorbed doses can cause radiation poisoning to humans and other mammals and cause malfunction of devices. The present study aims to simulate the motion of charged particles through arbitrary highly-charged electrostatic shielding systems in space environments to secure a safe zone from radiation exposure.

We considered three representative particles coming from the sun: 2MeV H+, 6MeV H+, and 22.5MeV Fe6+ in a lab-scale environment. Two types of shields were tested: electrode array and grid structure. The deflection of the particles was measured using a fluorescent screen and a timepix device at various angles and conditions. Many numerical experiments were conducted to reproduce the experimental data and to secure a 50% particle reduction in a safe zone compared to the initial number of particles. The shield geometry of two different shapes was compared with their performance through kinetic energy distribution data of electric charge and particles. As a result, the layered grid structure shows a reduction of 67% at 2MeV hydrogen and 53% at 22.5MeV iron particles. The preliminary designs considered in this research give us inspiration and useful information about what is theoretically possible.

About the speaker:

Dr. Bohoon Kim is a postdoctoral fellow in 389T at JPL. He was a postdoctoral fellow at Caltech in 2018-2019 after receiving his Ph.D. in Mechanical and Aerospace Engineering at Seoul National University in Korea in 2017 and his M.S. in Aerospace Engineering at Konkuk University in 2011. He obtained his B.S. in Aerospace Engineering at Konkuk University in Korea in 2009. Dr. Kim’s research covers systematic modeling of radiation shielding for spaceflight, shock-driven hydrodynamics in condensed phase energetics, fluid dynamics on turbulent flow, and interfacial instabilities.