Re: starship-design: combined fuel-track/electron beam ?

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

Kevin 'Tex' Houston wrote:
>Timothy van der Linden wrote:
>> Hi Kevin,
 
>> You had a thought:

>yeah, and it almost died of lonliness  ;)

I lost my e-mail, but anyway I don't understand the context.  Is
this about the acceleration or deceleration run?

IMO, we should really concentrate on the deceleration run, because
almost everything that can be used for the deceleration run can
be used for the acceleration run just as well, but not vice versa.
 
>> >1) give the fuel pellets a net positive charge.
>> To accelerate the pellets by electrical means?
>Yes, partly, but also to help the ship draw them in.

>> >2) accelerate the pellets with magnetic and electrical means

Keep in mind that there's a real limit to how fast you can
accelerate these pellets with an e-m launcher.  Besides the
serious problem of heating up the pellet, the length of a
launcher increases with the square of the desired muzzle
velocity (assuming no friction losses).

For instance, suppose a 10cm e-m launcher can acheive 100km/s.
In order to acheive 100,000km/s, a launcher would have to be
1,000,000 times as long, or 100,000km long.  And that's assuming
no friction or other speed related losses.

>> >3) launch the fuel so that the fastest part is launched first.
>so that at any given moment, the fuel is in front of the ship, and the
>electron beam is behind it.
 
>> >4) as the ship launches, beam electrons at it.
>> To make the ship attractive for the pellets?
>Also to have an energy input and to cancel the net positive charge you
>would be accumulating.

A problem with charged pellets, and especially an electron beam, is
that they will be deflected by magnetic fields, making aiming them
very difficult near the solar system.
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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