Newsgroups: sci.physics.plasma
From: FAIRFAX@CMOD2.PFC.MIT.EDU
Organization: MIT Plasma Fusion Center
Subject: Alcator Progress 7/28/94

Alcator C-MOD Weekly Highlights
July 28, 1994

The maintenance/repair period is continuing. The major activities this week
are concerned with refining and testing a redesign of the OH coaxial bus.

The problem in the original OH2L bus resulted from insufficient compliance to
accommodate the differential motion of the inner and outer coax connections. A
redesign concept which incorporates additional flexibility has been developed.
Detailed finite element analysis of this concept is in progress, and a test
piece is being fabricated. Additional testing of the coaxes removed from the
tokamak is continuing.

In situ re-surfacing of the terminal plate on the OH2L coil is in progress.
The liquid nitrogen shroud that surrounds the core has been opened to allow
examination of the OH coils. There is no evidence of any damage to the coil
structure. The LN2 passages will be flushed out and a final inspection made
prior to re-sealing the shroud.

While the bus work proceeds, we are also carrying out other maintenance and
upgrade activities. The divertor shunts, which measure the toroidal
distribution of halo currents during disruptions, have been removed from the
machine and will be upgraded to improve signal quality and reliability.
Additional halo current diagnostics, including a segmented toroidal rogowski
coil linking the inner wall, are being prepared. The isolation amplifiers used
to bring magnetics signals to the hybrid control computer have been replaced
with an improved design, developed in-house.

The PPPL transport analysis code TRANSP has been integrated with the MDSplus
data system. All TRANSP inputs, outputs, and control parameters are read and
written directly to the C-Mod data archive. Preparation and preprocessing of
TRANSP inputs, and post-processing analysis of TRANSP outputs, is conducted
using X-windows based software written in-house.

We have had preliminary discussions with Dr. Jack Sugar of NIST about a possible
collaboration which would involve searches for impurity emission lines with
diagnostic potential.

Bruce Lipschultz is attending an ITER Divertor and Divertor Modeling Experts
Group meeting this week.

[Background information for these reports from MIT are given
in the newsgroup's July posting #46 on Alcator C-MOD.]