10. Does a VASIMR® engine produce an ion beam?
No. In contrast to most other electric propulsion devices, VASIMR® technology does not apply a direct current or voltage to accelerate ions. Therefore, it does not produce an ion beam in any stage of its operation and does not need a neutralizer. Instead, the RF waves used by the VASIMR® booster stage, in concert with the static magnetic field, naturally have the correct polarization to heat the ions in the plasma without the need to separate those ions from the electrons. The plasma remains quasi-neutral throughout the entire heating process, so a VASIMR® engine could more accurately be described as producing a "plasma jet".
A couple of classic texts describing the propagation of radio-frequency (RF) waves in magnetized plasma are:
"Waves in Plasmas" by Thomas H. Stix, (ISBN 0883188597) American Institute of Physics, New York (1992) and
"Kinetic Theory of Plasma Waves: Homogeneous Plasmas", by Marco Brambilla, (ISBN 0198559569) Oxford University Press (1998)