Why MHD propulsion won’t work


Them space engineers are always looking for promising new ways of a-jettin’ and a-zoomin’ around the solar system. They’ve looked at conventional rockets, ion propulsion and even solar sails and nuclear drives. But nobody has spent much time dreamin about magnetohydrodynamics.

The principle is relatively straightforward–shoot a charged particle through a conducting ring and the way it interacts with the ring’s magnetic field should generate a force. One advantage is that this form of propulsion gets its thrust from the charged particles in the solar wind and so needs no on board fuel.

Now Marian “Thruster” Soida at Jagielonnian University in Poland and a pal have carried out an admittedly superficial analysis that suggests this form of propulsion could produce useful amounts of thrust. They reckon the thrust would be in the range of a few millinewtons for a metre-sized ring which is comparable with ion propulsion.

But there’s a big problem with their conclusion: they assume they have a current of 1 kiloAmp flowing around this ring. That’s a helluvalot of current to get from solar panels so perhaps these guys are thinking nuclear. Even then there would be all kindsa issues with cooling and onboard power management

The researchers say the idea is promising and more detailed calculations should be done. But a kiloAmp is gonna be deal-breaker for most engineers.

Ref: arxiv.org/abs/0712.1487: MHD space sailing

3 Responses to “Why MHD propulsion won’t work”

  1. Bruno van Wayenburg says:

    Couldn’t it be a superconducting ring?

  2. KFC says:

    Yep, but then ya gotta whole lotta cooling to do involving giant flasks of cryogenic liquids that gradually boil away and eventually run out. Zat really gonna be any better than carrying giant flasks o’ cryogenic fuels?

  3. Igor Carron says:

    I know of no “serious” proposals using these MHD devices that does not consider nuclear as being the way to produce that current.

    With regards to cooling, in space all the heat is radiated out and that works in T^4, so t’em radiators don’t need to be that large.