Alcator C-MOD Weekly Highlights
					May 5, 1994

The Phase II (1994) operating period is underway. The restart is proceeding
somewhat more slowly than anticipated, but progress is being made. 

Breakdowns were obtained on Thursday, but the OH2L power supply was found not
to be responding properly to its control signal, which prevented normal field
tuning to improve the null. This problem was not solved until Tuesday,
although workarounds enabled us to get breakdowns on Friday as well. The
supply problem only surfaced when the OH2 supplies were run under voltage
(hybrid) control near their PLC current limit settings, which had not been
done in prior tests. It was found that a pot in the regulator circuit, which
had been replaced over the winter hiatus, had been installed improperly. 

More reliable breakdowns were obtained on Tuesday, and tuning of the null led
to an early (5msec) breakdown and up to 20kA of current, but no subsequent
current rise. Signals from an inner wall flux loop (F25) were found to be
suspect. Elimination of this loop gives rather different reconstructions of
the field structure, and much of Wednesday was spent trying to determine the
best way of dealing with this situation. By the end of the day, a shot with
over 30kA of plasma current was obtained, more tuning was required to get a
good current rise. 

A current rise to 150 kA was finally obtained on Thursday. The reconstruction
of the null using a synthetic signal for the bad F25 loop based on a
combination of adjacent loops looks reasonable. Discharge development is
proceeding.

In the ICRF area, all coax parts for the transmission line to the D-port
antenna are in-house. The transmission line diagnostics for the D-port antenna
have been calibrated. Installation of the tuning and matching system has begun. 

The second Neutral Particle Analyzer (NPA) is undergoing final assembly and
testing at F port. The analyzer has been hooked up to the  vacuum vessel and
first alignment has been performed. Power, control and water cooling for its
internal magnet are being hooked up and  tested. The data acquisition system
will be installed and tested in the  near future. Software development,
including system control, data acquisition, and analysis is still proceeding.

The YAG Thomson scattering laser has been fired through the machine under
computer control. Stray light levels at the laser line have been observed.
Work is proceeding toward operation of this important diagnostic during plasma
operation. 

Steve Wolfe presented a talk on C-MOD results to the Columbia University
Department of Applied Physics Plasma Physics Colloquium on April 29.