From: IRBY@CMOD2.PFC.MIT.EDU
Subject: Alcator C-MOD Weekly Highlights
Organization: M.I.T.
Newsgroups: sci.physics.plasma


Alcator C-MOD Weekly Highlights
January 28, 1997



Reassembly of Alcator C-Mod was delayed somewhat this week
when the EF1L coil high voltage ringing test did not not meet
specifications. Breakdown occurred between the coil terminal and one of
the newly installed mounting plates. To fix this problem the mounting
plate was removed, the coil insulation was repaired, and the edge of the
mounting plate was machined back away from the coil terminal block. The
repairs are complete, the coil has been rung successfully, and we will soon
continue reassembly.
All work on transmitter #1 switchgear is complete, and we are
now making similar modifications to the switchgear for the #2 transmitter.
Work on the crowbar system and triggers for the new transmitters continues
as does fitup of the new coax. Coax runs have been layed out from the final,
to the phase shifter and stub tuner, and then to the entrance to the cell.
The required components are being fabricated at PPPL. All fault detection
circuit boards for the new transmitters have been completed.
Work on the power systems concentrated on new overvoltage protection
boards for the EF4 supply. These boards use breakover diodes to detect
overvoltages on the EF4 bus and trigger crowbar protection circuitry.
The power systems group is also pushing forward with DNB installation.
The new grounding system for the DNB is complete, specifications for the
modulator/regulator are being generated, and the holding tank for oil used by
the DNB supplies has been specified and is in fabrication.
Upgrades to the glow discharge system are underway. The maximum
resistance selectable under PLC control has been increased. This change
will add some protection for invessel components during glow discharge
conditioning. Hall current sensors have been added to the glow system
so that the current to each glow electrode can be measured without
regard to bias resistor selection. The fabrication of shutters for
protecting the new tangential two-color interferometer (TTCI) mirror and
the re-entrant window used by our wide angle camera is complete.
Assembly of the the TTCI shutter is also complete and cycle tests should
begin soon.
Dave Terry was at U Texas last week discussing DNB issues. Earl
Marmar attended the latest FESAC meeting in San Diego where
discussions where held on the upcoming FESAC ITER review. Franco Porcelli
of the University of Torino, Italy, just visited C-Mod. Dr. Porcelli
is involved in a collaboration on sawtooth activity involving C-Mod staff
and members of the PSFC theory group. He also presented an informal seminar
"Comments on X-point Dynamics". Dave Johnson, Boris Grek, and Joe
Bartolik from PPPL are at MIT this week working on the edge Thomson
scattering system.