Magneto-Hydro-Dynamis Propulsion

[portinari232]

This is my first post on this forum, but i have browsed through this website a bit and found it very interesting so i thought i'd post a new thread... so here goes:


Can someone please explain how MHD Propulsion works. I saw a little bit of a show about this on the Science channel recently but was unable to grasp it completely.

 

[Astronuc]

MHD propulsion works by applying an EM force to a conductive working fluid, like sea-water.

ele.unipv.it/~fis/fisica2mn/barca_a_prop_MHD.pdf

In a square channel two opposite faces employ two conductors with the a potential difference applied. This induces a current (I) flowing through the working fluid. On the other two faces a magnetic field (of strength B) is applied.

The propulsive force is proportional to IxB, by virtue of the Lorentz force, F = q(v x B) or written another way, F is proprotional to I X B.

I am not sure if you are asking specifically for this example, but there are other propulsion systems, e.g. magnetoplasmadynamic (MPD), using a similar principle but in the form of coaxial electrodes.

In this case, the current flows radially, and making use of self-inductance, the I x B forces propels the plasma axially.