NASA SBIR 01-1 Solicitation


PROPOSAL NUMBER: A6.02-9011 (For NASA Use Only - Chron: 012988 )
Field Emission Cathode for Electrodynamic Tethers

Electrodynamic (ED) tethers offer the potential of propellant-less propulsion with infinite specific impulse (Isp). To achieve it, an efficient electron source that contacts the space plasma without using propellant must be coupled with the ED tether. At present, the electrons are supplied by a hollow cathode (HC) plasma contactor with complex propellant management and storage and power-processing unit that typically dominate the ED tether system mass. Busek therefore proposes the development of a field emission electron source that uses no propellant, and is less massive and less complex than the HC system.

In Phase I we will design, build, and test a field emission array cathode (FEAC) using Busek-grown carbon nanotubes as the emitters. The FEAC will consist of four paralleled emitter cells that will be tested individually and as a combined FEAC panel. The cell technology was already demonstrated as a neutralizer on a laboratory colloid thruster. Scaling up this technology while maintaining adequate current density is the major Phase I challenge.

In Phase II, a complete FEAC panel system consisting of many cells will be developed per typical ED tether requirements. The system will include the FEAC power-processing unit and emission control circuitry for autonomous tether current matching.

The ED tether equipped with a FEAC space plasma contactor is likely to find commercial applications primarily as a deorbitting device for spent upper stages, failed spacecraft, and spacecraft at the end of their useful life. Deorbitting is now mandated by recently established NASA policy. A FEAC with significant total current would also greatly enhance the performance of low power Hall and ion thrusters as well as colloid and FEEP thrusters.

Terrestrial applications of FEACs cover all areas of vacuum electronics. A large FEAC panel with many cells would be ideal for programmable billboard displays and stadium scoreboards. Additional applications include e-beam guns, microwave tubes, scientific instruments, x-ray sources, etc.

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR (Name, Organization Name, Mail Address, City/State/Zip)
Vlad Hruby
Busek Co. Inc.
11 Tech Circle
Natick , MA   01760 - 1023

NAME AND ADDRESS OF OFFEROR (Firm Name, Mail Address, City/State/Zip)
Busek Co. Inc.
11 Tech Circle
Natick , MA   01760 - 1023

Form Printed on 06-19-01 15:44