Alcator C-Mod Weekly Highlights
			   August 11, 2003


We continued our maintenance period last week.  Progress was made on
the lower hybrid, ICRF, and alternator systems.


Physics 
-------

Stewart Zweben, PPPL, was on-site for two weeks from July 21 through
August 1. He was continuing his analysis of an experiment
(mini-proposal #330, executed on June 6, 2003) in which we attempted
to create H-mode discharges via edge ICRF minority heating and fast
ion loss. Crucial shots in that experiment are being analyzed using
the TRANSP code, which is being run by Catherine Fiore. Although no
H-modes were observed, the post analysis has allowed us to determine,
among other things, the RF power deposition profiles, magnitude of the
minority ion tail, and the subsequent ion loss. Dr. Zweben is planning
to continue these studies with more analysis and with new experiments
in the next campaign.


Alternator
----------

The alternator inspection is proceeding.  The rotor is being
pulled from the alternator housing following removal of the housing
end covers and the alternator-flywheel coupling.  Bearing surfaces
will be tested over the next few days to determine if any re-babbitting
work will be required.


Lower Hybrid
------------

PPPL efforts this week concentrated on polishing the copper plating
and testing the losses of the forward stacked waveguide guides.
Results from low power tests of stack #2 indicate that the average
improvement for all the polished guides together is 0.025 dB.  The
tests will be repeated again next week to determine if an oxidation
layer returns that affects the measured losses. Selected guides of
Stack #1 were polished this week, and then it was reassembled and
tested. The preliminary results of these tests indicate greater
improvements than measured on Stack #2 due in part to improved
polishing techniques.

Fabrication by the vendor of the two interface flanges for the forward
waveguide assembly is complete, and the flanges will be delivered to
PPPL early next week.

A gas break was ordered and will be delivered next week for the high
power tests of the rear waveguide (RWG) at MIT. This gas break will
allow low pressure nitrogen or dry air to flow in the RWG while
maintaining a higher nitrogen pressure in the transmission line
leading from the klystron to the test area.

Testing of a SFOL (serial fiber optic link) transmitter prototype for
the Lower Hybrid Control System is expected to be complete by next
week.  Progress continues on the vector modulator and I/Q detector
testing chassis.

The prototype circulator has been returned to MIT by the vendor and is
being prepared for high power tests.  The prototype has been modified
to allow pressurization of the circulator to the original MIT design
specification.  The remaining eleven circulators, also with the
modification, have been shipped by the vendor and are expected at MIT
in a few days.


ICRF Systems
------------

The FMIT#2 transmitter is ready for testing and re-tuning subsequent
to the driver control grid capacitor replacement. Tests were delayed
by high humidity conditions in the power room.  The MIT funded upgrade
to our power room, which includes a new air conditioning system, should
eliminate such delays in the future.

Preparations continue for operation of the the FMIT#3 and #4
transmitters at 50 MHz.  The new positions of the dummy load and
tuning stub among other components have been determined.  Fabrication
of new components and modifications to old ones are expected to begin
in the next few days.


Travel and Visits
-----------------

Jim Irby was at PPPL last week to serve on the NSTX TF Flag review
committee.
 
Huang He, UTexas, is at MIT to help in the disassembly of the power
system for the old Texas DNB, which will be redeployed by the
Texas group on another experiment.