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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Re: Antimatter
Message-ID: <8603132246.AA02680@s1-b.arpa>
Date: Thu, 13-Mar-86 18:18:25 EST
Article-I.D.: s1-b.8603132246.AA02680
Posted: Thu Mar 13 18:18:25 1986
Date-Received: Sat, 15-Mar-86 19:04:53 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 33

Storing frozen antihydrogen:  surround the antihydrogen ball with a
spherical shell cooled to near 0 K.  A gas atom emitted from the wall
will travel in a random direction until it strikes another wall or
the pellet.  The chance it hits the pellet instead of another wall
can be reduced arbitrarily far by increasing the radius of the shell.
If the mechanism by which gas atoms are liberated is radiation
bombardment from the antimatter then for sufficiently large shell
radii the chain reaction dies out.  By the way, an explosion with
the force of "trillions of H bombs" would require the annihillation
of tens of millions of tons of antimatter.  Might we make it in
gram quantities first?

Getting antihydrogen:  we can currently make antiprotons at miserably
low efficiency (~10**-6).  Techniques have been developed and tested
for cooling the antiprotons (reducing their velocity dispersion) and
for decelerating them.  Positrons are easy to produce by pair production.
Recently techniques have been developed for slowing atoms by interactions
with laser light; sodium atoms have been slowed to a few meters/second by
this mechanism.  The same techniques should work with antihydrogen.
The atoms could then be plated out (slowly!) on antihydrogen pellets.

Using antimatter:  Even at current prices, antimatter might be useful
for triggering "clean" fusion weapons.  Reduce the cost by two or
three orders of magnitude and it could be useful for rocket fuel.
It would be used to heat much larger quantities of (say) hydrogen.
To guide antihydrogen into a rocket engine would be tricky but not
obviously impossible.  A small quantity would be vaporized by laser;
the resulting gas ionized with ultraviolet light and the resulting
plasma guided by magnetic fields.  Alternately, charged antihydrogen
pellets might be manipulated intact by electrostatic fields.

Antimatter and fusion are both terribly speculative.  I personally
like beam powered spacecraft; they seem much more practical.