starship-design: Re: Antimatter Annihilation Products

[TLG.van.der.Linden@tip.nl (Timothy van der Linden)]

Steve wrote in a reply to Rex:

>If the result of a proton-antiproton or proton-antineutron annihilation
>is a lot of high-velocity particles, there's no point to trying to
>capture those and turn them into electrical energy to accelerate
>reaction mass.  Either throw the reaction products directly out the back
>or play them into your reaction mass to heat it, then throw the hot
>reaction mass out the back.
>
>I have never understood Timothy's claim that lower exhaust velocities
>are more efficient.  My own conclusion is that, physics permitting,
>converting mass directly into photons provides the highest payload
>velocity for a given amount of fuel mass.  Lower exhaust velocities mean
>higher fuel-and-reaction-mass-to-payload ratios and expending more
>energy to accelerate a given payload plus the additional reaction mass.

The difference between your and my approach is that you minimize the amount
of mass of the ship, while I minimize the amount of energy needed.
(At least that is what I see in a letter from you of Sep 1st, 1995)

Tim