Carbon Nanotube Field Emission Cathode for Electric Space Propulsion
Summary:
Busek Company, Inc. (Natick, MA), has developed field emission cathodes (FECs) based on carbon nanotubes. The non-thermionic devices have onset voltages about an order of magnitude lower than devices that rely on diamond or diamond-like carbon films. The FECs could be used in all types of vacuum electronics, and Busek is already working with a maker of general science instruments as well as companies specializing in colloid and field emission electric propulsion (FEEP) thrusters for space propulsion.
Technology Description:
Busek’s field emission cathodes (FECs) are based on carbon nanotubes produced using a proprietary process. Electron emission occurs at the sharp edges of the nanotube, which is only about 20 nanometers in diameter. Because of the dimensions and feature sharpness of the nanotubes, they emit electrons at lower voltages than other types of emitters. Busek has measured onset voltages of 1.2 and 1.4 volts per micrometer, which is about an order of magnitude lower than devices that rely on diamond or diamond-like carbon films. The Busek FECs are cold emitting so, unlike thermionic FECs, they do not require a heat source.
MDA Origins:
Busek received a Phase II SBIR from BMDO to explore FECs as smaller, more efficient alternatives to hollow cathodes for electric propulsion devices.
Spinoff Applications:
Terrestrial applications include all types of vacuum electronics, including flat-panel displays, microwave devices, and radars. In addition to thrusters, the Busek FECs could make possible a new form of space propulsion: space tethers, which do not require propellant. Aging satellites could one day unfurl long current-carrying tethers that use FECs to contact the space plasma, which returns the current back to the opposite end of the tether. Interaction of the current in the tether with the Earth’s magnetic field causes the satellite to slow down and its orbit to decay.
Commercialization:
Busek recently delivered to the Jet Propulsion Laboratory a colloid thruster system that uses the new FECs, and Centrospazio, a space technology lab in Pisa, Italy, has committed funds to test the Busek FECs with field emission electric propulsion (FEEP) thrusters. Busek is also developing relationships with companies that make general science instruments requiring an electron source, such as scanning electron microscopes.
Company Profile:
Busek is a privately held company, established in 1985. The company specializes in plasma devices, electric space propulsion, and materials processing. Busek provides analytical, computational, and experimental services to government and industry.
Contact Information:
Vlad Hruby
Busek Company, Inc.
11 Tech Circle
Natick, MA 01760-1023
Tel: 508-655-5565
Fax: 508-655-2827
email: busek@busek.com
web: www.busek.com
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