Geoffrey A. Landis wrote:

It's cool to see that Robert Winglee has been awarded a NASA Institute
for Advanced Concepts (NIAC) project to develop a plasma beam to push
a M2P2 magnetic plasma sail for space propulsion. It sounds like an
excellent project which has the potential to revolutionize high
delta-V space propulsion.

I do want to mention that, in part, the concept develops out of my
previous study of a particle-beam pushed magnetic sail, presented at
the 2001 STAIF Conference:

G. A. Landis, "Interstellar Flight by Particle Beam," presented at the
Space Technology and Applications Intenational Forum Albuquerque NM,
Feb. 11-15, 2001. American Institute of Physics Conference
Proceedings Volume 552, pp. 393-396.

Coincidentally, the refereed-journal version of this article has just
come out:
G. Landis, "Interstellar Flight by Particle Beam," Acta Astronautica.
Vol 55, No. 11, 931-934 (Dec. 2004). [Copies available by request.]
It is published online via ScienceDirect: (
http://authors.elsevier.com/sd/artic...9457650400133X )



What keeps the beam from spreading, and how are plasma instabilities
(due to the energy available from the motion of the plasma beam
relative to the ambient plasma) addressed?

Paul