From: "Edward L. Ruden" <edofnm@highfiber.com>
Newsgroups: sci.physics.plasma
Subject: Re: A simple question.
Date: 3 Nov 1997 18:11:20 GMT
Organization: Air Force Phillips Lab.
Message-ID: <01bce884$5c5f2e40$3e64ee81@RUDEN.PLK.AF.MIL>
References: <63bb5l$obi93@chinook.Generation.NET>

Gauche <haaa@hotmail.com> wrote in article
<63bb5l$obi93@chinook.Generation.NET>...
>
> Do you know why the plasma propulsion can't be use on earth and do you
know
> a website where I can find information about plasma propulsion?
>
> Felix
> denext@generation.net

Two reasons present plasma propulsion schemes don't work on earth are

(1) The plasma sources usually operate at pressures below atmospheric,
meaning that air would rush in an quench the thruster
(2) Although specific impulse (momentum imparted to the craft per unit mass
of fuel) is high, thrust is insufficient to counteract gravity, even given
the lift of an airframe.

These are not intrinsic limitations to the concept of using plasma as a
propellant, simply limitations of presently employed schemes. Plasmas are
routinely produced in the laboratory well above atmospheric (albiet usually
pulsed) such as in ICF targets, and can potentially provide thrust in
excessive of the gravitational force on the craft (search "Project Orion").

Ed