Alcator C-MOD  
			Weekly Highlight Report 
			July 8, 1993

Following the run on Friday, July 2, we began a brief scheduled maintenance
period. This is our first downtime since beginning the current campaign
nine weeks ago. The goals of this break include some minor vacuum work,
modifications to cell ventillation, upgrades to PLC softare, power supply
maintenance and installation of additional interlocks, cryo system upgrades
and repairs, installation of the pellet injector, connection of the coax
from the transmitter to the ICRF antenna, and installation of additional
lighting and cable trays in the cell.  Operation is scheduled to resume
the week of July 19. 

The machine was allowed to warm up over the holiday weekend, and a short
clean vacuum opening was carried out on Tuesday to remove a damaged mirror,
install a new pulsed gas valve at A-port, and perform some additional minor
maintence. The vessel was closed and back under vacuum Tuesday night, and a
high temperature bake was begun on Wednesday, July 7. 

The pellet injector has now been installed and aligned on C-port. Work on
the other tasks, including installation of the RF coax lines, is proceeding
on schedule.

During the last days of plasma operation before the shutdown, the ICRF
antenna loading was measured as the plasma position with respect to the RF
limiter was adjusted. Results indicate that satisfactory coupling should be
obtained when we begin heating experiments.  Our wall conditioning studies
were extended by observing the effects of extensive ECDC in He, carried out
overnight prior to the run of Friday, July 2.

A preliminary analysis of sawtooth behavior has been carried out. The
results indicate that we are typically observing phenomena characteristic
of "ideal" rather than Kadomtsev-like instabilities. There are only small
precursor oscillations, lasting typically a single cycle, and crash times
are short. This behavior is unlike what we typically observed on Alcator C,
and is similar to observations on JET.