Measurements of secondary mass flux from a surface bombarded by an [EMIM][BF4] electrospray plume

Rao, Avinash

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https://hdl.handle.net/2142/122016 Copy

Description

Title

Measurements of secondary mass flux from a surface bombarded by an [EMIM][BF4] electrospray plume

Author(s)

Rao, Avinash

Issue Date

2023-12-04

Director of Research (if dissertation) or Advisor (if thesis)

Rovey, Joshua L

Department of Study

Aerospace Engineering

Discipline

Aerospace Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Electrospray
• Secondary Mass Flux
• QCM
• Facility Effects

Abstract

Electrospray propulsion systems operate by electrostatically extracting high speed droplets, clusters, and molecules from an ionic liquid propellant. These high speed species can impact and interact with surfaces in proximity of the propulsion device, producing an amorphous plume of secondary species. The aim of this research is to demonstrate a methodology for measuring the mass of a differential component of the secondary plume to better understand how electrospray thrusters interact with their terrestrial test facilities and their in-space environment. Experiments conducted utilized a quartz crystal microbalance to investigate the energy dependence of secondary mass flux as well as the angular distribution of secondary mass for high voltage and low voltage primary electrospray plumes. The secondary mass flux yields was observed to have very little dependence on the energy of the primary plume, with yield values contained within 6.822×10−14 ng ion-sr and 8.873×10−14 ng ion-sr over an order of magnitude of primary voltages. The angular distribution of the secondary plume produced by a low energy primary plume was relatively flat, with yields ranging from 7.391×10−14 ng ion-sr to 8.828×10−14 ng ion-sr over a range of 35◦ to 80◦. When spraying a high energy plume, the yield dropped from 7.304×10−14 ng ion-sr to 3.645×10−14 ng ion-sr when the polar position of the quartz crystal microbalance was swept from 35◦ to 80◦. These results indicate that the high energy plume produces a secondary plume with less mass than atomic carbon sputtering nickel, but more mass than if the carbon atoms simply bounced off the surface of the target. Results at varying primary energies require further investigation in a more pristine experimental environment to make any statements on the underlying effects.

Graduation Semester

2023-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Avinash Rao

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