Development of Space Environmental Testing Facilities for Assessing Combined Effects
Open Access
- Author:
- Beckerle, Matthew
- Graduate Program:
- Aerospace Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- June 17, 2024
- Committee Members:
- Sven G Bilén, Thesis Advisor/Co-Advisor
Robert G. Melton, Committee Member
Amy Pritchett, Program Head/Chair
Sean David Knecht, Committee Member
Jesse Kane Mc Ternan, Special Signatory - Keywords:
- atomic oxygen
space environment
material interactions
space environmental testing
thermal cycling
outgassing
plasma diagnostics - Abstract:
- Space is a harsh environment for Earth-orbiting spacecraft. In low Earth orbit (LEO), spacecraft are exposed to upper atmospheric interactions from solar and cosmic radiation, thermal extremes, vacuum, atomic oxygen, and ionospheric plasma. Ionospheric plasma can cause sputtering and spacecraft charging that can short-circuit onboard electronics. Atomic oxygen causes oxidative corrosion for many different materials. Outgassing and thermal cycling can cause surface erosion and material failure from expansion and contraction, respectively. This thesis documents the set up of a thermal–vacuum environment and characterization of an atomic oxygen source using argon gas. The first environment is the thermal–vacuum system that contains an internal cold plate and was characterized for thermal cycling and outgassing. It also includes a residual gas analyzer to facilitate outgassing tests following ASTM standards. The second environment is facilitated by an atomic oxygen source, which ionizes the incoming gas in its discharge chamber utilizing two filaments. The discharge chamber is surrounded with high-field strength samarium–cobalt magnets that confine the volume occupied by the internal plasma to promote more collisions. Downstream of the discharge chamber are two electrostatic grids that provide an accelerating electric field for atomic oxygen ions while also preventing charged particles from propagating downstream. These ions encounter trapped electrons to promote recombination and expel out as atomic oxygen neutrals. Three plasma diagnostic devices are used to measure the expelled particles of the atomic oxygen source including a Wien filter (or E × B probe), a retarding potential analyzer, and a Faraday probe. Experimentation of the source using argon gas allows for an understanding of the expelled particles since argon ions will interact with the plasma diagnostic tools. The RPA attached to a mobile X–Y table measured the concentrations of streaming and charge-exchange ions. A Faraday probe provided a constant current density of 3.46 × 10^(−6) mA/cm2 showing that the source provided a constant stream of ions. Combining this source along with other space environmental testing capabilities provides a better understanding of how materials interact with the surrounding environment.