Alcator C-MOD Weekly Highlights
			August 11, 1997


	The Alcator C-Mod maintenance period continues.  Work last week was
focused primarily on the alternator repair, RF maintenance, DNB
installation, Core Thomson Scattering calibration, and an up-to-helium for
installation of a new preionization source.
	Work on the alternator by our contractor (Mechanical Dynamics
and Analysis, inc.) involved mostly site preparation.  An area
behind the alternator house was cleared out, and a temporary building is
being erected where the field coils will be cleaned and reinsulated.
A trolly system has been installed that will be used to move
the coils from the alternator house to this new area.  Work on the rotor
last week included the removal of approximately half of the rotor
wedges.
	Maintenance on the RF system is continuing.  Power has been partially
installed for the new RF racks in the power room allowing testing of
transmitters 1 and 2 into a detuned dummy load. During the last run
period we experienced arcing in one of our 40-80 MHz dummy loads.
This problem has been discussed with the manufacturer and proposed
modifications await a final review.
	The DNB plasma source was prepared for high vacuum. Vacuum seals and
damaged filaments were replaced, and installation hardware was collected in
preparation for mating the source to the accelerator.  Arrangements were
completed for access to Torvac, the main C-Mod vacuum controller. An
appropriate gatevalve for the final installation was chosen, operation of
gauge controllers verified for use as the required interlocks, and PLC
logic modifications and cabling identified.  Control power has been run to
variac, suppresser transformer rectifier, arc/filament/snubber primary
controller.  480 VAC power has been run to variac and the accelerator
supply cabinets.  Modifications to the waveform generators used with the
arc and mod/reg supplies were designed, and modifications to the suppresser
transformer/rectifier were completed.  Modifications to the suppresser
switch design were started.
	On Tuesday and Wednesday of last week the C-Mod vessel was backfilled
with hydrogen and then argon so that Core Thomson scattering calibrations could
be performed.  This calibration work will continue this week.  An up-to-helium
was performed on Thursday to install a new preionization source.
	Early this year Alcator C-MOD provided a gross vacuum sample
to the Idaho National Engineering and Environmental Laboratory (INEEL) for
particle size analysis, SEM/EDS analysis, and BET total surface area
analysis.  Analysis of this particulate has been completed and results are
comparable to similar data collected from the General Atomics DIII-D vacuum
vessel.  Jon Carmack and Dave Petti who have done this work at INEEL are now
preparing a report of this analysis.  Alcator C-MOD and the INEEL plan
continued collaboration and further analysis of particulate to be collected
during the next C-MOD vent.  This data is very important for determining
environmental safety limits for ITER, particularly since the C-Mod data
represents the first data from a machine with metal walls.
	Ken Gentle, UT-FRC, visited to discuss pulse propagation experiments
and how best to use the high density C-Mod plasmas to continue investigation
of apparently non-local transport phenomena observed at lower densities in
other devices.  Specifically, he discussed the use of impurity injection
with John Rice, L-H transitions with Amanda Hubbard, and pellet injection
with Earl Marmar.  An attempt will be made to use existing data from these
perturbations so that research can continue until targeted experiments are
conducted during the continuation of the current campaign.
	Dave Johnson and Joe Bartolick visited from PPPL last week to work on
the X-point Thomson scattering system.
	Tom Fredian participated in the DIII-D Data Analysis Workshop at
General Atomics, and made a presentation on the MDSplus data system. DIII-D
is considering adopting MDSplus as part of their data analysis upgrade.