Alcator C-Mod Weekly Highlights
			Sept 22, 1997


The maintenance period continued at Alcator C-Mod last week. The alternator
repair, DNB, and RF upgrades are progressing.  We continued electron
cyclotron discharge cleaning experiments.

The last of the twenty field coils is being installed on the
alternator rotor.  All tests, including hi-pots to 6 kV, on all but the
last coil have been successfully completed.  Remaining tasks include
installation of the field coil jumpers, support blocking, and retaining
rings. A several day long bake to cure the rotor insulation is also
required along with several more hi-pot tests.  On the present
schedule, installation of the rotor inside of the alternator housing
will begin next week. 

Calibration and testing of the FMIT#1 and #2 interlock system is nearing
completion.  The phase balance detectors were tested and set.  This
interlock checks the phase between the top and bottom antenna current
in one antenna strap.  This phase is normally 180 deg. An arc is
registered if the phase changes by +/-45 deg (0.25 V).  The voltage
limit was also tested and set.  This interlock limits the peak
voltage on the antenna to below a predetermined value (40 kV).  The position
feedback circuit is being bench tested.   Position feedback is used to
maintain the loading at a pre-set value to facilitate RF operations
under H-mode conditions by variation of the plasma position.  The PLC work
on FMIT#3 and #4 continues as well.

Design of the fueling systems for the DNB were completed.  It was determined
that existing components could be used, and construction is now underway.
The largest of the transition boxes for the high voltage, low capacitance
transmission line, and the frames for all of the other transition boxes were
completed.  Work continues on assembly of the vacuum system controls and
layout of the beamline in the cell. A detailed design of the suppressor switch
interface to the PLC and master control system has been started.  Drawings
and wirelists for the vacuum system were updated and corrected.

The ECDC experiments continued with more scans of the resonance position
and fill pressure as density and temperature data was obtained with the energy
analyzer and Langmuir probe.  Preliminary analysis indicates the electron
density outside the resonance position is in the range of 1 to 1.5e16 m-3 and
is spatially rather flat over a 30 cm range.  The electron and ion temperatures
are both approximately 2 eV and also have very broad spatial profiles. The
density drops quickly inside the resonance with a decay length of < 3 cm.  A
stainless steel rod coated with 200 A of diamond-like graphite was inserted
to within 4 cm of the resonance.  The graphite was completely
removed in less than 3 hours by the discharge in a region from
12 to 16 cm outside of the resonance position (the resonance position was
not scanned during this experiment).  Other regions of the probe showed
less graphite removal and possibly some redeposition.   Bill Wampler (Sandia
Laboratory collaboration) will use a proton backscatter technique to provide
quantitative information on the radial profile of the graphite.

Left out of last week's report was the attendance of Martin Greenwald
at the ESnet Steering committee meeting from Sept 8-12.

Bob Granetz was in Lausanne, Switzerland last week attending an MHD Expert
Group meeting.  Most of the time was spent writing and editing sections
of the ITER Physics Basis document.