[AR] Re: NASA test of quantum vacuum plasma thruster (was "Anyone heard of this?")
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 5 Aug 2014 11:31:45 -0700
Michael Clive <clive@xxxxxxxxxxx> wrote:
snip
> Why do I want to do this? This would change the entire game as far as
> mars colonization and settlement is concerned.
Michael, I work on making power satellites economical. That's not of
interest to SpaceX (Musk) but the propulsion problem is similar in
delta V.
I have not seen the paper, but someone quoted to me that they were
seeing 30-50 micronewtons.
Let's assume the power level was on the order of a kW and gave ~40
micronewtons or ~40 micronewtons per kW.
For electric thrusters, a kg of reaction mass per second accelerated
to 20 km/s (typical VASIMR) acquires a Ke of 1/2 mV^2. This takes 200
MW (at 100% efficient).
The force is 1kg x 20,000 m/s or 20,000 Newtons, 100 N/MW or 0.1 N/kW,
which is 100,000 micronewtons per kW.
Reducing this number is the VASIMR efficiency (~70%) and the reaction
mass fraction, which for LEO to GEO and this exhaust velocity is
around 20%. Earth to Mars is similar.
It's still 1000 times more energy effective to use ion engines,
assuming I have not made some boneheaded error.
Keith Henson, L5 Society founder and EE (if you still need one)
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