Session 7IB - Alternative Concepts.
INVITED session, Thursday morning, November 14
Grand Ballroom, Adam's Mark
(This work sponsored by the U.S. Department of Energy)
(Coauthors Martin M. Schauer and Travis B. Mitchell)
Several years ago, it was proposed (D. C. Barnes, et al.), Plasma Phys. Control. Fusion 35, 929 (1993) that a dense nonneutral plasma could be produced in a Penning trap. Nonneutral plasmas have excellent confinement (for reasons which may be easily stated). Thus, such a dense plasma might produce simultaneously high density and good confinement (as needed for fusion). Recently, this theoretical conjecture has been demonstrated in a small (3 mm radius) electron experiment (PFX). Densities up to 35 times the Brillouin density (limiting number density in a static trap) have been observed by strong (100:1) spherical focussing . Electrons are injected at low energy from a single pole of the sphere. A surprising observation is the self-organization of the system into a spherical state, which occurs precisely when the trap parameters are adjusted to produce a spherical well. This organization is observed by a bootstrapping which produces a hysteresis. Additional observations which confirm the dense spherical focus are energy scattered electrons and deflections of an electron probe beam by the space charge of the central focus. PFX is described. These observations are detailed and examined theoretically. Ions are produced from a low pressure gas puff system and trapped in the virtual cathode formed by the central electron focus. Recent experimental observations on such electrostatically confined ions will be presented.