|arya||Date: Saturday, 25-June-2011, 0:47 AM | Message # 1|
This double layer can be thought of as a thin standing shock wave across which there exists a strong electric field gradient. It is this electric field that accelerates ions from the source plasma to very high exhaust velocities creating thrust. Because the double layer is purely the result of plasma density, system and magnetic field geometry, no accelerating grids are required. Also, because there is equal flux of electrons and positive ions from the thruster there is no need for a neutraliser. It is in this sense that the HDLT is a "true" plasma thruster as it ejects equal numbers of both positive ions and negative electrons.
Power is required only for the maintenance of plasma and the creation of the magnetic field. In our current bench top prototype, 250W is sufficient to create several milli-Newtons of thrust. In space the solenoids that generate the 250 Gauss of magnetic field this requires we estimate could be cooled to 200K, reducing the resistance in the coils by a factor of 5 and representing a power consumption of a few 10s of Watts. Relative to other existing systems this constitutes quite a power saving and is well with-in the capabilities of solar panels. The 0.5sccm of feed gas represents a mass consumption of 160 mg/hr, so that a typical 5 hour burn would use 0.8g of propellant.
Full article/source - http://nextbigfuture.com/2009/02/mit-mini-helicon-plasma-space.html
Message edited by aryanwarrior - Saturday, 25-June-2011, 0:51 AM