🚀 go-pugleaf

dietz@cs.rochester.edu (Paul Dietz) writes:

> In article <C0Jv2M.74z.1@cs.cmu.edu> rcs@cs.arizona.edu (Richard Schroeppel) 
> 
> > Since fusing protons is so hard, why not use deuterons?
> > They fuse at a lower temperature, and the reaction only
> > requires regrouping the nucleons, rather than invoking the
> > weak force to transmute p->n.  The Earth's d/p ratio is ~.0001.
> > Perhaps the ramscoop collector could selectively enrich d,
> > by selecting for atoms having a magnetic moment.
> 
> 
> Or, better yet, why fuse anything at all?  One can do the following:
> decelerate the incoming material a bit producing some power.  Now,
> accelerate some on-board reaction mass using this power, so that the
> two streams are now at the same speed.
> 
> Done properly, the thrust from the second part exceeds the drag from
> the first part.  The decelerated interstellar material needn't even be
> laterally compressed.
> 
> This scheme seems counterintuitive, but it violates conservation of
> neither energy nor momentum.  The kinetic energy of the vehicle
> does not increase with time, it only gets concentrated in less
> and less mass.
> 
> All these schemes suffer because the local ISM is so damned thin.  The
> solar system appears to lie inside a bubble of very thin, hot gas,
> perhaps the result of some "recent" supernovae in our neighborhood.
> 
> 	Paul F. Dietz
> 	dietz@cs.rochester.edu

But, again, that involves carrying on-board fuels, which is the _BIG_ 
advantage of the Bussard Ramscoop.  Carrying antimatter for the purposes 
of accelerating to a point where you are independant of it is not too bad 
a price to pay for the eventual fuel-independant p-p fusion, and even 
carrying some deuterium if you have to is not too bad, as that too should 
eventually be outgrown.  Carrying reaction mass with the intention of 
supplying it for the entire journey is hardly advantageous.

Also, the Bussard Ramscoop would be lucky to accelerate to the point 
where ISM is really useful inside of the solar system, so I don't think 
we'll have a problem with that.  It could take MONTHS to reach the 
velocities necessary for p-p fusion...

                                                Jason Cooper