Alcator C-MOD   
			    Weekly Highlight Report  
				September 9, 1993


Alcator C-MOD is now in the third week of a planned three-week maintenance
period. 

The vessel is presently undergoing a 120 degree C bakeout, following the
"clean" vent at the beginning of the maintenance period. The cryo-system is in
bakeout mode, providing LN2 cooling to the coils to maintain their temperature
at acceptable levels during the bake.

The reactors needed for safe four-quadrant operation of the OH and EF1 power
supplies have been received from the vendor and are being installed. The
additional varistors required to allow higher pre-charge currents (above 25kA)
in the OH2 circuits have been installed.

The 2-d Thomson scattering diagnostic is now being installed in the C-MOD cell.
This unique system features an optical design which allows the beam of the
pulsed (50Hz) Nd:YAG laser to be moved acoss the plasma during a plasma shot,
providing spatially-resolved measurements of the electron density and
temperature profiles in the radial direction; an array of spectrometers
view the beam, providing spatial information in the vertical direction.
Initially, two spectrometers, out of a planned total of eleven, are being
installed. 

The grazing incidence, time resolving, VUV spectrograph diagnostic has been
installed; this system has a spectral range of 20A to 1050A and is used to
study high- and low-Z impurities. In addition, a 3 spectral channel
Multi-Layered-Mirror based instrument, built and calibrated by the plasma
diagnostics group at the Johns Hopkins University, has been installed. This
instrument will measure emissions at 3 soft x-ray wavelengths and will be used
primarily to monitor 3 different charge states of Molybdenum. For this reason
we are referring to it as the 'Moly Monitor'.

Modifications to the gas feed logic in the PLC/Paragon program have been
implemented. These changes will allow quicker and more reliable pre-fill
during the operating cycle.

Benjamin Welch of the U. of Maryland Lab for Plasma Research is visiting this
week for discussions and coordination of experiments involving his Optical
Multichannel Analyzer diagnostic. This diagnostic has been operational
throughout this year's operating campaign.