High Energy Plume Impingement on Spacecraft Systems

AFOSR Telecon

Jarred Alexander YoungOctober 22, 2012

Electrical Issues

All components biased relative to ground May prevent beam

generation

Beam Diagnostics thrown off by Decel Grid Bias

Solution: Convert to generic Ion Engine electrical configuration

Quantity Bias (V) Power SupplyBias

above/below ground (V)

Anode/Beam Voltage (AN)

250A0150NX05

(x2)+250

Discharge (DC) 70 A0100MX25 +180

Emitter Filament (EF)

10 A20H950 +170

Accel Grid (AC) 290 N01HA30 -290

Neutralizer Filament (NF)

10 (?) HY3010E-3 +10

Electrical Set-up for 5000 s ISP beam

Beam Diagnostic Testing

Beam analysis using FC-71A RPA/Faraday Cup

Mounted in center of engine beam

Determines Beam Current

▪ Ion Density▪ Ion Flux

Beam Energy

Goal To develop a matrix of

possible test settings and corresponding fluence times

+

+

Beam Diagnostic Test Plan

Test Variables Main Emitter Filament Current (4.5, 5, 5.5 A) Discharge Voltage (30-70 V) Accelerator Grid Voltage (100-290 V)▪ 290 V corresponds to 5000 s ISP

Beam I-V Curves Take I-V Curves from every point in text matrix▪ Calculate Ion Density and Flux

Take derivative w.r.t. Voltage to find Beam Energy Distribution

Compile energy distribution data

Upcoming Tasks

Conduct beam testing and analysis

Design mount for material coupons

Procure Equipment Filament power supply should arrive by

mid-week Diagnostic Equipment▪ Keithley 2410 Sourcemeter in by end of week▪ Keithley 6485 Picoammeter status unknown