  Injection of relatively high density spheromaks with significant
helicity-content into a tokamak has been proposed as a means for fueling and
current drive. The CHI (Co-axial Helicity Injection) device was devised to
inject current to the STOR-M tokamak. Various circuit modifications were made
to the CHI controls, enabling testing of various injection configurations. The
charge/discharge circuits for CT formation/acceleration and stuffing field were
modified, and the power supplies and power converters were replaced. Various
modifications were implemented to solve the original slow bank triggering
problems. The CHI device was mounted on STOR-M for radial and vertical CT
injection at various times. Spheromak injection into STOR-M usually resulted in
disruption of the tokamak discharge. After modifying the CHI device to operate
at increased power, it looked like tokamak current was increased by a few
kiloamps just prior to disruption, but careful testing proved that the signals
indicating a current drive were actually spurious, caused by inductive pickup.
The CHI device was attached to a portable vacuum chamber that was constructed
from spare parts, to characterise the CTs produced. Magnetic probes were
constructed to measure poloidal and toroidal field near the CT edge. Langmuir
probes were made and returned reasonable estimates for edge CT density and
temperature.
