Ultra-Low Cost Advanced Ionic Liquid Ion Source Electrospray Thrusters for PocketQubes

Michael Bretti

Background

• Founder of Applied Ion Systems• Only independent maker-based at-

home R&D program for advanced plasma/ion thrusters

• Ultra-low cost, easy to manufacture, open-source thrusters

• Provide resources for hobbyist, educational, enthusiast, PQ, and nanosat communities

Basic Principles of Electrospray

1. Liquid fuel actively or passively fed through some capillary/porous structure

2. High voltage applied between emitter and extractor

3. At high enough fields, liquid Taylor cones form at end of capillaries/pores

4. Ions/droplets pulled from cone and accelerated through extractor aperture

Ionic Liquid Ion Source (ILIS)

Overview• Room temperature molten ionic salt fuel (EMI-BF4, EMI-Im)• No neutralizer/heaters• Wide-range of ISP (<800 to >5000s), moderate-to-high thrust/power (14uN/W-57uN/W)

Emission Modes• Colloidal – droplets (high thrust, low ISP)• Mixed-Mode - droplets/ions (medium thrust, medium ISP)• Pure Ionic Regime (PIR) – ions (low thrust, high ISP)

Emitter Types• MEMS silicon etched hollow capillary arrays• Laser ablation micromachined porous glass spike arrays• CNC machined macroscale porous glass/metal spikes/ridges• Vertically grown CNT forests on micromachined porous glass spike arrays

Advantages of ILIS Electrospray at the PocketQube Level

• Only a few types of EP technologies that can reasonably scale in terms of size, power, performance, and non-pressurized fuel requirements at the PQ level• PPT, VAT, ILIS, MEMS Resistojet

• Highest combination of thrust/power and ISP at this scale• Less EMI than pulsed systems• Passively fed fuel, no heaters, no neutralizers• Stable, safe, wide temperature range, vacuum compatible fuel• Extreme miniaturization• Wide performance range – low thrust/high ISP to high thrust/low ISP

AIS-ILIS1 Ionic Liquid Electrospray Thruster V6

Specifications (Currently Tested V6 Prototype)

• Size: 45x45x16mm• Dry Mass: 39g• Fuel: EMI-BF4• Fuel Capacity: 1g• Emitter: CNC Machined Glass Ridge• Nominal Thrust: 0.04uN• Peak Thrust: 0.4uN• ISP: 4144-4320s• Vin: 5V• Power: <0.4W• Accl. Voltage: up to +/-5kV

CNC Machined Porous Glass Ridge Emitter

Glass: P4 FritDisc Diameter: 25mmDisc Thickness: 4mm (total)Ridge Height: 2mmRidge Length: 20mmRidge Tip: 0.1mmRidge Base: 2mm

3D Printed Housing

High Vacuum Fueling of the ILIS1 – Degassing, Saturation, Baking

Reasons for Fueling in High Vacuum• Complete saturation of porous glass• Fuel degassing• Porous glass degassing• Baking/desorption of water• Improved thruster operation

ILIS1 Benchtop Qualification – HV Test Load

Extractor Geometry Optimization

Standard Linear Slit Extractor Enhanced Flared Slit Extractor

Extractor Geometry Optimization

Wide Slit, Thin Extractor Plate Narrow Slit, Thick Extractor Plate

Extractor Geometry Optimization

ILIS1 V5 Test – Ion Beam Plume and Post Test Analysis

ILIS1 V6 Test – Ion Beam Plume and Post Test Analysis

AIS-ILIS1 V7 Iteration – New Housing and Shield Electrode

AIS-ILIS1 V7 Iteration – New Housing and Shield Electrode

Second Emitter Development Phase - AIS-ILIS1.2

Pushing the Boundaries of PQ Ion Thruster Performance The AIS-ILIS2

Power: 1.6WThrust: >20uNISP: >3500sTotal Impulse: >50NsVolume: 45x45x27mm

AIS-ILIS2 – Spike Array Emitter

AIS-gPPT3-1C Micro Pulsed Plasma Thruster

AMSAT-Spain GENESIS Integration with the AIS-gPPT3-1C

AIS-EPPT1 Micro Pulsed Plasma Thruster

New Experimental AIS PQ Thrusters In The Works!

• Solid Iodine Fueled Micro-Resistojet• AIS-VAT1 (Vacuum Arc Thruster)• AIS-VAIT1 (Vacuum Arc Ion Thruster)• AIS-EPPIT1 (Pulsed Plasma Ion Thruster)

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THANK YOU!