Micro-Cathode Arc Thruster for Propulsion

Michael Keidar

Mechanical & Aerospace Engineering The George Washington University

In collaboration with: T. Zhuang, A. Shashurin, G. Teel, D. Chui, S. Haque, J. Lucas, C. Parvini, J. Slotten, S. Hurley, T. Lee (GWU), J. Kang, C. Dinelli, K. Castonguay, I. Maloney (USNA), O. Tintore, E. Agasid (NASA Ames), P. Calhoun (NASA GSFC)

Acknowledgement: NASA DC Space Grant Consortium

Micropropulsion and Nanotechnology Laboratory (MpNL) 2

Satellite Propulsion Trends

Inmarsat 4; 6 tons; $500 M • Mass-to-orbit is the major cost driver for satellites • Chemical rocket fuel ~ 50% of mass • Industry response- electric propulsion

“The all-electric satellites gives us our customers the weight advantage, which we “ satellites are fueled with a hope will allow them to reduce substantial amount of liquid their launch costs,” chemical propellant, accounting Roger Krone, President for 50% or more of the satellites' Boeing Network & Space total weight and adding millions Systems to the cost of launch.” The Era of Small Satellites

• Displacing larger satellites for some MOST 125 lbs applications $2M • Often piggyback on rockets with large satellites Current electric propulsion cannot scale down into most small satellites Perceived risk to a primary payload prohibits propulsion for the smallest of small satellites- & Nanosatellites CubeSat, 2 lbs, (<25lbs) ~$100K Propulsion requirements

• Electric propulsion that is… – Low-cost – Reliable and simple – No pressurized tanks – Power efficient – Scalable and modular – Safe for the satellite and launch vehicle

Solid propellant

Micropropulsion and Nanotechnology Laboratory (MpNL) Outstanding issues with microthrusters

3.0

experiment 2.5

2.0 simulation

1.5

Radial distance (mm) 1.0 6 J; 6 hours; 0.25" DIA

-2.4 -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 Recession depth (mm)

charring

AFRL micro-PPT

Keidar, JPP, 2004 Contamination

Weakly ionized plasma Micro-cathode arc thruster (µCAT) Velocity measurements

Time-of-flight

ΔV~104 m/s

In agreement with measured PIC simulation PIC simulations

Magnetic field

No magnetic field NASA Ames PhoneSat NASA sponsored students: Orbitals’ , April 2013 Experiment George Teel Dereck Chiu

Phonesats “Alexandre”, “”, “”, (“Zoidberg” ) Launched on Maiden Flight of Orbital’s Antares (April 2013)

• NASA Ames PhoneSat selected micro-CAT

Android app compatible with PhoneSat Bus will be capable of commanding uCATs USNA flight experiment NASA sponsored students: George Teel Joseph Lukas Thruster Head Design

Anode Teflon Shell (Brass Screw)

Ceramic Insulator Aluminum Housing Cathode (Titanium) Ballistically Reinforced Communications Satellite (BRICSat-P) Launch, May 20 2015 Mission Update

The preliminary on-orbit data shows that the propulsion system was able to reduce initial tumbling from an estimated 30 º/s to within 1.5 º/s after 48 hours. Summary of micro-CAT performance

Current: 7/8 Keidar et al, Plasma Phys. Contr. Fus, 2014 New flight experiments

NASA sponsored students: George Teel CANYVAL-X Yonsei U/NASA Joseph Lukas Cameron Parvini Towards high thrust to power microthruster

• Main inefficiency: electron losses; • 90% current is conducted by electrons • Utilizing electron energy Summary

• Micro-CAT is well suited for CubeSats: – 10-20V, ~0.1 W power requirements – 2000-3500s Isp (<2000 s for Ni, higher thrust !) – Impulse bit (1 micro-Ns per 0.1 W) – Scalable up to 5 W/unit (50 Hz) – Small footprint and system mass – Can be used for de-orbiting • Applied magnetic field leads to uniform cathode erosion and ability to throttle the thrust