  The magnetic compression experiment at General Fusion was a repetitive
non-destructive test to study plasma physics to Magnetic Target Fusion
compression. A compact torus (CT) is formed with a co-axial gun into a
containment region with an hour-glass shaped inner flux conserver, and an
insulating outer wall. External coil currents keep the CT off the outer wall
(radial levitation) and then rapidly compress it inwards. The optimal external
coil configuration greatly improved both the levitated CT lifetime and the rate
of shots with good flux conservation during compression. As confirmed by
spectrometer data, the improved levitation field profile reduced plasma
impurity levels by suppressing the interaction between plasma and the
insulating outer wall during the formation process. Significant increases in
magnetic field, density, and ion temperature were routinely observed at
magnetic compression despite the prevalence of an instability, thought be an
external kink, at compression. Matching the decay rate of the levitation coil
currents to that of the internal CT currents resulted in a reduced level of MHD
activity associated with unintentional compression by the levitation field, and
a higher probability of long-lived CTs. An axisymmetric finite element MHD code
that conserves system energy, particle count, angular momentum, and toroidal
flux, was developed to study CT formation into a levitation field and magnetic
compression. An overview of the principal experimental observations, and
comparisons between simulated and experimental diagnostics are presented.
