Jon Berndt wrote:

Nowhere is mention made that this particle beam causes any "equal and
opposite" action at the particle-beam source. If this near-Earth station is
blasting a particle beam into space that causes a spaceship to accelerate
(momentum transfer) to "tens of thousands" of mph ... what is the source
doing to maintain position or orbital velocity? Am I missing something?

If the transmitter is in orbit around Earth, the net effect would be
to displace the orbit slightly, so that the momentum is transfered
to the planet.

Paul