Alcator C-Mod Weekly Highlights
				Nov. 17, 1997

There were no operations on Alcator C-Mod last week. As noted in the previous
report, during the morning startup procedure on Thursday, Nov 6, a ground
fault indication was observed on the newly re-wound alternator rotor. The
fault showed up only at slow rotation speeds and did not occur during full
load operation with excitation applied. In response to this indication,
tokamak operations were suspended.

MD&A, the company that performed the rewind, dispatched a team to MIT to carry
out repairs. That work has proceeded on a double-shift, seven-day-week basis. 
The rotor has been pulled and inspected, and the fault location determined. The
retaining ring at the affected end of the rotor was removed, and wedges were
removed for a few feet from the #1 slot. The fault cleared as one of the
wedges was removed; a small steel sliver which may have been responsible was
observed during removal of the wedges. Inspections and further testing are
continuing.

The power systems group assisted MD&A and alternator staff in measurements on
the rotor. In addition, testing of the TF current feedback circuit was
undertaken to determine the cause of noise in the cabinet #1 regulator signal
observed on one shot on November 5, and previously on a single shot in June;
this work is still in progress. 

During the hiatus, several jobs involving the PLC control system are being
carried out. The in-cell CRYO rack, which includes temperature sensors for the
magnet systems and cryogenics controls, has been re-organized and cleaned
up. Control power for the thermocouple sensors on the toroidal field magnet,
and control power for the ECDC system, has been re-routed so that it no longer
depends on the TF supply cabinet being energized. An evaluation of the default
power-on status for all PLC control systems is in progress.

Progress continues on the preparation of the diagnostic neutral beam
system. The crowbar that will protect the DNB Mod/Reg tube was successfully
bench tested to half of the required voltage.  Based on these very postitive
results, the testing will be completed after installation of the crowbar and
its trigger source in the Mod/Reg cabinet.  The high voltage, low capacitance
transmission line continued its progress through the power area toward the
cell and corona hardware for the section between the power supplies and the
cell was completed.  The conditioning system for the oil in the accelerator
supply is now under construction.

Most of the C-Mod physics team is attending the APS Division of Plasma Physics
Meeting in Pittsburgh this week. 

A clean-up and replacement of ceiling tiles in the C-Mod Control Room is being
carried out this week. As a result, most of the C-Mod computer cluster has
been taken off-line. E-mail and data access should continue to function.