MadSci Network: Physics |
The link you
referenced explains the process with words and graphics.
(http://w
ww-aero.meche.rpi.edu/Research/LaserPropulsion/laser_propulsion.html)
“The high pressure, high temperature plasma created by the laser absorption
cools and expands out the rear of the vehicle, producing the thrust
which
propels the lightcraft into the sky.”
The expansion
process
appears similar to that of the Linear Aerospike engine (http://boeing.com/defense-
space/space/propul/RS2200.html).
As for thrust
created
through accelerating atomic particles (electrons and ions), we only need
to look
to Newton’s Second Law of Motion: F=ma.
Since electrons and ions have a finite mass, and they are
accelerated
through a grid, this process produces thrust.
This is also in accordance with the law of conservation of
momentum.
Ion propulsion is used as the main propulsion system of Deep Space
1 (http://nmp.jpl.nasa.gov/ds1/).
Ion propulsion is far more efficient than chemical propulsion, but
provides very low thrust levels (http://nmp.jpl.nasa.gov/ds
1/tech/sep.html).