RE: starship-design: Fusion Cone Scoop

[Steve VanDevender <stevev@efn.org>]

L. Parker writes:
 > First, drag on an electromagnetic scoop: Not an issue, since the scoop is
 > _attracting_ the ionized atoms, it is generating a net pull against a
 > (relatively) stationary object. There IS NO drag, you realize acceleration
 > out of the scoop process instead.

 > Second, ionization of the interstellar medium:  Requires only lasers, and
 > relatively low powered ones at that. See Forward et. al., too many
 > references to  list here.

That depends on how asymmetrical the scoop field is.  It doesn't peg my
implausibility meter to consider the possibility of having a scoop field
that attracts ionized gas in front of it.  And yes, lasers are going to
be much more effective at ionizing a large quantity of gas than any
particle beam would be.

 > Third, ignition of fusion burn: No outside ignition source required, the
 > magnetic fields generated by the scoop and the velocity of the accelerated
 > ionized atoms create a stellerator type fusion engine (Podovsky? I'm not
 > sure...it was a Russian though.)

I'm wondering you couple the ship to the fusion exhaust such that the
ship realizes thrust from it.

 > The only catch is getting the thing up to a velocity where it will work at
 > all, very much like an air breathing ramjet. And yes, the density of the
 > interstellar medium is still an issue. The lower the density, the greater
 > the velocity required for ignition.

Presumably if you can get that ramscoop fusion system going you've
already figured out how to fuse stationary hydrogen, so just run a more
normal fusion reactor off of a booster tank of hydrogen fuel to get up
to the speed where you can ignite the ramscoop fusion system.  Assuming
that's not up into high relativistic speeds, anyway.