NASA SBIR 2004 Solicitation


SUBTOPIC TITLE:Precision Constellations for Interferometry
PROPOSAL TITLE:Radio Frequency Micro Ion Thruster for Precision Propulsion

SMALL BUSINESS CONCERN (Firm Name, Mail Address, City/State/Zip, Phone)
Busek Co. Inc.
11 Tech Circle
Natick ,MA 01760 - 2213
(508) 655 - 5565

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Kurt   Hohman
11 Tech Circle
Natick, MA  01760 -2213
(508) 655 - 5565

TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
Busek proposes to continue development of an engineering model radio frequency discharge, gridded micro ion thruster that produces sub-mN to mN thrust precisely adjustable over a wide dynamic thrust range. Phase I testing proved the feasibility of the concept and estimated performance was exceptional. Measuring beam current and voltage, a thrust up to 1.6mN, thrust efficiencies up to 40% and propellant utilization up to 80% were estimated. Specific impulse ranged from 500-3000seconds. Beam power maximum was 38 watts and the rf power at this maximum was about 30watts total and approximately 20 watts rf deposited into the plasma. The rf discharge ionizer eliminated any need for an internal cathode. In Phase II, Busek will measure thrust directly, characterize the thruster over a wide range of operating conditions and predict lifetime. MIT will advance a numerical simulation of the rf thruster to be used for scaling and design purposes. For missions with cryogenic sensors, a thruster utilizing non-condensable propellant(s) will be evaluated. In addition, a beam neutralizer will be investigated. An rf cathode or carbon nanotube field emission cathode are the two most promising neutralizers.

POTENTIAL NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Missions such as LISA, TPF, MAXIM, SIM, etc., require extremely precision propulsion. Colloid thrusters have demonstrated that sub-micro Newton precision and thrust noise can be achieved. The ST7 DRS mission will document that this thrust precision yields s/c position accuracy within a few nanometers. Propulsion with higher but overlapping thrust and relaxed precision is required for the coarse constellation adjustments and for reorientation of the constellation to observe other locations in the universe. Many of these missions require cryogenic sensors and therefore, the propulsion effluent should not thermally radiate or condense on cryogenic surfaces.

POTENTIAL NON-NASA COMMERCIAL APPLICATIONS (Limit 1500 characters, approximately 150 words)
Busek is a major participant in the field of micro propulsion and currently has the largest US commercial diversity in micro propulsion. In this niche, Busek has developed the only commercial 200W Hall thruster to be flown August 2005, near flight ready colloid thrusters (NASA ST& DRS) and soon to be flown micro-ppt developed in conjunction with the US Air Force. In addition, Busek is developing a micro resistojet in another NASA SBIR Phase I with Goddard as the technical monitor. The addition of a micro rf ion thruster will supplement the range of thrust and performance of our thrusters nicely and the heritage of the suite of subsystems developed or nearly developed, such as PPU and propellant feed systems, will lend to easier commercialization. Potential Department of Defense and commercial applications will become available as the continued miniaturization of spacecraft matures.

Form Printed on 08-01-05 13:52