Design, demonstration, and space qualification of an ultraviolet LED based charge management system
Abstract/Contents
- Abstract
- When a spacecraft is in orbit, it is subject to numerous disturbance forces due to atmospheric drag, solar pressure, and other sources. Over the past several years, a number of missions ranging from tests of General Relativity to Earth observation have been proposed which require correcting for these disturbance forces so that the satellite can follow an orbit entirely dictated by the gravitational force, called the geodesic. One architecture that allows for this behavior is called "drag-free, " where the spacecraft contains a shielded free floating test mass. This test mass follows the geodesic and the spacecraft in turn follows the test mass. Thus, the spacecraft also follows the geodesic. While the test mass housing shields it from most disturbances, high energy particles in the space environment can penetrate the housing leading to charging of the test mass or the surrounding housing, leading to a voltage difference and a resulting electrostatic disturbance force. Controlling this charge is critical to meet the performance requirements for drag free sensors. Charge management using photoelectrons generated by the 254 nm UV line of Hg was first demonstrated on Gravity Probe B and is presently part of the LISA Pathfinder technology demonstration. My dissertation presents a new method of charge control using UV-LEDs operating at high frequency outside the science band of the proposed missions. I first present the results of ground tests and space qualification studies of the UV-LED devices showing less than 5% change in key performance parameters of the devices. Next, I present the design and results of a lab based demonstration of the AC charge management system which can successfully raise and lower the test mass potential. Next, I present the design of a satellite mission designed to test the UV-LEDs and AC charge management system in-situ, followed by the results of the mission. I show that key properties of the UV-LED devices change by less than 8% in flight and the AC charge management system is capable of bringing the test mass to within 200 mV of the spacecraft housing. Finally, I present results of materials coating studies, showing that various carbides including SiC and Mo2C are suitable for use as test mass coatings.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Balakrishnan, Karthik |
|---|---|
| Associated with | Stanford University, Department of Aeronautics and Astronautics. |
| Primary advisor | DeBra, D. B. (Daniel B.) |
| Primary advisor | Hollberg, Leo (Leo William) |
| Thesis advisor | DeBra, D. B. (Daniel B.) |
| Thesis advisor | Hollberg, Leo (Leo William) |
| Thesis advisor | Lipa, John A |
| Advisor | Lipa, John A |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Karthik Balakrishnan. |
|---|---|
| Note | Submitted to the Department of Aeronautics and Astronautics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Karthik Balakrishnan
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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