Hello Dr. Thomas,

Welcome to the 'Board!

I found your paper at:

http://nlspropulsion.net/Documents/propulsion_poster.pdf

and I read through it. Using a linear accelerator to efficiently move electrons at very high speed is pretty interesting. Unfortunately, I can't seem to duplicate some of your computations...

Assuming an electron beam current of 85 A, and an electron ejection velocity of "670,603,679 miles per hour" (299,786,669 m/s) I get a thrust of only 23.3 Newtons:

mdot=gamma*Me*I/q where mdot is the rate of mass expulsion from the
vehicle (the exhaust mass)
gamma=the relativistic mass factor
=1/sqrt(1-ve^2/c^2) where ve=the exhaust velocity,
c=speed of light.
Me=9.1094*10^-31 kg (electron mass)
I=85 A (Coulomb/sec)
q=1.602*10^-19 C (electron charge)

gamma = 1/sqrt(299786669^2/299792458^2)
=160.9

mdot = 7.777*10^-8 kg/s for the exhaust mass rate. This is the actual mass expelled per unit time.

Thus from the fundamental rocket equation: F=mdot*ve we have:

F=(7.777*10^-8 kg/s)*(299,786,669 m/s)
=23.3 N
For a million kilogram vehicle, this thrust will impart the acceleration:

a=F/10^6 Kg
=2.33*10^-5 m/s^2 (2.4 micro g's)

So to me this implies: 1) Either the speed of the electrons exiting the vehicle are much less than nearly c (light-speed) or 2) The beam power (and beam current) must be proportionately higher, say about 500,000 times.

Could you shed some light on this?

Thanks!

Ty Moore
"GoogleNaut"

-- Edited by GoogleNaut at 19:32, 2008-04-16

-- Edited by GoogleNaut at 16:40, 2008-04-19