Reply To: reference to electric field propulsion?

[Augustine]

Well the drawback to VASIMR is that it requires a power source and that the power source will have mass. The best bets are solar with a stretched lens array that provides something like 250-500W/kg or nuclear power. Solar isn’t useful past the orbit of Mars and to get to Mars in a reasonable time period you would want a square kilometer of solar cells. Nuclear requires shielding and radiators, preferably to be used with a high temperature nuclear reactor (which can be used to minimize radiator mass).

I think that a DPF will have less mass than either option. I’m worried about the VASIMR magnetic field(s) mucking with the magnetic field of the DPF, and I am worried about how a ship does station keeping when its power source also produces some thrust (perhaps a bank of ion thrusters to counteract the thrust generated by the alphas?).

If you believe in Polywell (and I am pulling for them) then a Polywell reactor has the benefit of scaling to produce gigawatts of power, much of it as heat and alphas. You can dump the heat and current into water/hydrogen to produce enormous thrust which is handy for getting mass to low earth orbit.