Alcator C-Mod Weekly Highlights
				July 15, 1997

The C-Mod maintenance interval continued last week. No runs were scheduled. 
Due to the continuing alternator outage, there will be no tokamak operation
this week. 

The General Electric teams working on the alternator removed the rotor and
retaining rings, providing a clear view of the faulted region. Minor arc
damage was observed at one end of the rotor winding, near the retaining ring
location. Repair options are being evaluated. We presently anticipate about
a two-month downtime for the alternator repair, with a corresponding delay in
the operating schedule. 

Ian Hutchinson, Miklos Porkolab, Earl Marmar, Martin Greenwald, Brian
LaBombard, Amanda Hubbard, Jim Terry, Bob Granetz, and Steve Wolfe, as well as
several of our collaborators from PPPL and University of Texas, participated
in the National Tokamak Workshop July 8-10 at General Atomics in San Diego
last week. Plans for the C-Mod program over the next five years were presented
and discussed.  Martin Greenwald stayed over for a meeting on Friday to
discuss plans for an upgrade to the DIII-D data acquisition and database
system.

The high frequency (250 - 350 kHz) "streak" mode observed on magnetic pick-up
coils on shots with early ICRF heating (during the current rise) has been
tentatively identified as an m=5, n=3 mode rotating in the ion diamagnetic
drift direction, which is consistent with a TAE mode.  Further analysis is
under way and a collaboration with King-Lap Wong of PPPL has been initiated.

Maintaince work on the 80 MHz system is progressing.  Approximately half of
the PPPL demodulators have been recalibrated; the others will be recalibrated
as well to ensure their functionality.  Their calibrations have drifted <10%
since their last calibration.  Several additional demodulators have also been
refurbished.  The repair of the 40 MHz dummy load is progressing.  The center
conductor has been sent to RF Technologies for inspection.  Discussions are
underway with the manufacturer to determine the source of the problem, an arc
in the load at the teflon interface between the water and air sides.
Potential solutions under study include changing the water flow inside the
load, increasing the diameter of the center conductor, using a two stage
transformer, and pressurizing the coax up to the load with N2.

Preparation of the DNB power supplies continued with installation of
control hardware, conduit, cable trays, etc.  Fabrication of several duct
connectors for the low capacitance transmission line were completed.  Other
aspects of transmission line design, fabrication, and installation await
the results of the consultation on truss loading.  Development of the PLC
programming for the DNB continued principally with operator interface
programming.  Remaining assembly of the beamline awaits fabrication of
additional support structures which are in progress.

David Storek, UT-FRC, began a visit to install a BES spectrometer for
commissioning tests.  The spectrometer will be tested by observing
turbulent fluctuations in the ambient H-alpha light when the current
campaign continues.

G. Cima, UT-FRC, continued his visit and assisted with the calibration of
the heterodyne radiometer installed for the current campaign.