Micro-Cathode Arc Thruster for Small Satellite 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- CubeSats & 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’ Antares, April 2013 Experiment George Teel Dereck Chiu
Phonesats “Alexandre”, “Graham”, “Bell”, (“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