From: IRBY@PSFC.MIT.EDU
Reply-To: IRBY@PSFC.MIT.EDU
Subject: Alcator C-Mod Weekly Highlights
Newsgroups: sci.physics.plasma
Organization: MIT


Alcator C-Mod Weekly Highlights
January 4, 1998



Engineering:

Work on Alcator C-Mod last week focused on fixing the remaining small
vacuum leaks and completing the new HEAT system. A base pressure of
3 to 4 X 10-7 Torr has been obtained with one known leak remaining on the Core
Thomson Scattering alignment target actuator. The RGA indicates that the major
component making up the base pressure is water vapor (mass 18/ mass 28
~ 30), which is coming primarily from the outgassing of invessel components.
The leak has been fixed, we are pumping down, and we will soon do a final
leak check before beginning to bake the machine. The Heat system
is nearly ready for operation with 520 out of the 560 thermocouple channels
operational.

In addition to the primary work mentioned above, we have continued work on the
new ECDC waveguide run and Boronization and Gas systems. As soon as the
cooling jacket for the ECDC window has been installed the new waveguide run
will be complete. The ECDC control system has been checked out up to the point
of actually turning on the magnetron and checking forward and reflected power.
We expect this final step to be taken early this week. Only the water
sprinkler remains to be hooked up on the Boronization system, and we will begin
a Boronization system checkout using helium gas within the next few days.
The Gas system is together and awaiting a leak check and bake before it is
ready to be used. This system is required before we can complete the
Core Thomson Scattering calibration that was begun over the weekend.

We continue to bring both old and new diagnostics back on line. The
Soft X-ray and Magnetics systems are ready for operation. Improvements
to the TCI diagnostic are nearly complete, and we expect to begin alignment
of the interferometer in the next few days. A prototype Rangefinder system
using single-mode fiber optics to relay both the 0th and 1st order laser
beams to the machine is being tested. The rest of the ECE beamline was
installed in the cell, optically aligned and pumped. Baking of the high
vacuum section is in progress.

Work continued on modifications to the DNB Mod/Reg. This work included design
of some control electronics and construction of enclosures to accommodate
the new electronics. We continue to work on grid drive, fault monitor,
tube regulator, and tube monitor printed circuit board layouts and
fabrications.

Bus electronics calibrations and checkouts were completed last week. A great
deal of data was taken for bus current and voltage calibrations that is still
being analyzed. In addition, MOV Rogowskis, ground fault fuses and Pearson
transformers, analogue links to the Hybrid, and bus current alarms have all
been checked out and made operational. The Power Systems Group has now begun
calibration and checkout of all the Alternator electronics and CAMAC.