Theory suggests that electrical power can be generated in space by
connecting a wire between two orbiting satellites and pulling it through the Earth's
magnetic field. This device, called a electrodynamic tether, enables both the
conversion of mechanical (orbital) energy into electrical energy and vice versa. In
order to assure proper operation of this device, however, it is necessary to establish
electrical contact between each end of the tether and the ambient space plasma. The
device that will be used to make these connections is called a plasma contactor and
research into its performance and operating characteristics is being undertaken.
The plasma contactor can also be utilized to alleviate electrical charge
buildup on a spacecraft. Charging and subsequent uncontrolled discharging of a
spacecraft can interfere with the spacecraft instrumentation and control systems and
thus its mission. Current research is aimed at understanding the physics of the
plasma contactor. The work involves measuring the contactor electrical noise
production in an effort to assure it will not interfere with other spacecraft systems.
If you wish to know more about hollow cathode plasma contactors see our list of refrence papers.
Both pictures below are of operating hollow cathodes and their associated plasma plumes.