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starship-design: Re: ICAN

In a message dated 1/14/98 2:47:30 PM, lparker@cacaphony.net wrote:

>> No you missed the point.  By bleeding off exaust stream into a MHD
>> you convert some/all te kinetic energy of that part of the exuast streem
>> electricity.  You then use that electricity to add kinetic energyu to
>> of the exaust stream.  Effectivly your not adding any kinetic energy to
>> exaust streem, your just shuffling it around.  How does that add effective
>> thrust per pound of  fusion fuel?
>Oh, I see what you're saying. You are assuming the magnetic nozzle is also
>an accelerator - I wasn't. It may be that it is, in which case you are
>correct, that would clearly be an example of an entropy device! I will have
>to check the research and see exactly what it is meant to accomplish. I am
>afraid I did not read that paper all the way through, just the abstract, one
>can only read so much, especially when it isn't really job related...

I understand, my reading inbasket has turned into a full higth bookshelf.

But as a guess unless the magnetic field did act as an accelerator, it
couldn't accelerate the exaust stream any.  I.e. their would be no other
energy in the system that could be turned into extra kinitic energy.

>If you want to create an accelerator type of device out of magnetic fields
>there would have to be some sort of auxiliary power as well. My guess would
>be one or more fusion reactors of a more conventional sort. I think we can
>probably get sufficient ISP and thrust to weight figures without
>accelerators though. If we can up the strength of the nozzle field
>sufficiently then we can reduce the containment volume producing higher
>pressures than we could withstand with purely material walls.

I'm not sure about this would work.  Your still limited to the total energy of
the system.  Since its already puting out 100% as kinetic energy in its plasma
their not other source to accelerate it higher via the 'presure' of the

>I still believe that we are looking at more than fifty years though.

Hard to tell.  In the 40's no one would have bet we could get into space, or
be on the moon by the end of the '60's.  Over a couple years nothing changes
as much as you'ld expect, over decades everything changes more then you'ld