Document Type

Article

Journal/Book Title/Conference

Journal of Spacecraft and Rockets

Volume

57

Issue

4

Publisher

American Institute of Aeronautics and Astronautics, Inc.

Publication Date

3-19-2020

First Page

793

Last Page

808

Abstract

The emission of secondary and backscattered electrons influences spacecraft surface potentials and the surrounding plasma. Modern spacecraft use new materials for which secondary emission properties have been unavailable. In this work, the total electron yield (i.e., the sum of secondary and backscattered electron yields) was measured for niobium-C103 alloy, molybdenum Titanium, Zirconium, Molybdenum (TZM) alloy, tantalum-tungsten alloy, Elgiloy®, graphite lubricant (DAG 213®), and titanium nitride. The surface properties of tungsten were also measured for comparison with past test data. The materials were readied as spacecraft flight materials and temperature-treated ("annealed") to predicted peak flight temperatures. The yield properties for 10 eV-5 keV incident electron energies for all samples were measured. Both unannealed and annealed states were tested, except DAG 213, which was only tested annealed. Three-parameter and four-parameter models were used to fit the secondary and backscattered electron yield data, respectively. The emitted electron energy distributions are also obtained and fit with a Chung-Everhart model for secondary electrons and a Gaussian function for backscattered electrons. The secondary and backscattered electrons' current densities were calculated for different ambient plasma conditions. For ready reference, the normalized primary electron, secondary electron, and backscattered electron current densities versus ambient electron temperature were computed and plotted from 1 eV to 8 keV.

Comments

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