Newsgroups: sci.physics.plasma
From IRBY@CMOD2.PFC.MIT.EDU Wed Mar 20 21:57:35 1996
From: IRBY@CMOD2.PFC.MIT.EDU
Organization: MIT
Subject: Alcator C-MOD Weekly Highlights

Alcator C-MOD Weekly Highlights
March 20, 1996

Alcator C-Mod is currently up-to-air, but will be pumped
down again today so that further ECDC can be done to remove boron hydride
deposits on the outer wall and lower divertor cover plates. These
deposits formed during boronization at radii beyond which the ECDC
resonance was allowed to extend. The ECDC resonance will
now be run well out into the horizontal port extensions to break up
the hydrides and allow them to be pumped away. In-vessel work has therefore
been delayed. However, a great deal of other scheduled work has begun.
Transmitter #3 and #4 installation is moving rapidly now
that access to the power room is routine. Both crowbar cabinets
have been moved into the power room where modifications will continue.
The conduit for the #3 transmitter has been installed and HVDC and
control cables are being run. Water cooling systems and their
associated control and power components are being mounted on their
stands. The fixed frequency cavities have been removed from the
driver units in preparation for the tunable ones to be supplied as
part of our PPPL collaboration.
Cooling of our TF magnet during high field runs slowed down
our shot cycle considerably during the last run campaign. We are now
making modifications to the cryo system to speed up the cooldown
time. New valves will be added to the TF magnet manifold so that warmer
parts of the magnet can be selectively cooled at higher LN2 pressures.
The new system design is complete and major components are on order.
Modifications to the LN2 storage tank have begun which will provide
higher LN2 flow rates to the pump. A new LN2 pump has been
installed, and the old one sent out to be reconditioned.
We have also continued work on our diagnostic stand extension.
Most components have been fabricated and installation will begin next
week. This extension will provide much needed new floorspace in the cell
for future systems such as the diagnostic neutral beam (to be installed
in collaboration with the University of Texas).
Evolution of the finite-element model of the inner and outer
divertor continues. This model allows us to determine forces on the
divertor plates with various assumptions about halo and eddy current
distributions. Input of magnetics data from a C-Mod disruption
is being incorporated into the model. This effort is required to
ensure reliable operation of our new inner and outer divertor hardware at up
to 2 MA of plasma current.
Paul Bonoli is at the Sherwood meeting this week. Martin
Greenwald, Amanda Hubbard, and Darren Garnier attended the TTF workshop
in Philadelphia last week and gave talks. Alberto Loarte is visiting
from JET to collaborate on our divertor physics modeling effort. Don McDonald
and Bob Phelan visited from Boulder Metric, Inc. to discuss techniques for
improved absolute calibration of detectors from mm to visible wavelengths.