Alcator C-Mod Weekly Highlights
             September 10, 2007

FY2007 weeks of research operations:
     Target: 15 weeks
     Completed: 14.7 weeks


Operations
----------

Following the end of FY07 plasma operations on 8/31, liquid nitrogen was
removed from the cooling system, and a purge of gaseous nitrogen was
begun through the magnets and cryostat to maintain the cryostat above
ambient atmospheric pressure.  C-Mod is now at room temperature and is
being prepared for in-vessel work, and a borescopic inspection of the
E-left lower TF arm.

On Thursday and Friday approximately 12 hours of helium glow discharge
cleaning of the vacuum vessel was completed.  Glow discharge cleaning
allows more rapid manned entry to the vessel by breaking down some of
the heavier boron compounds that could otherwise pose a safety issue.
Several backfills with room air will also be required to further
neutralize these compounds.

On Wednesday backfills of deuterium and hydrogen were performed as part
of the end-of-run Thomson scattering calibration.  Following the
calibration, the removal of Thomson components at G-Hor was begun in
preparation for manned entry through that port.

During this up-to-air period our primary tasks will be to repair flux
loops, investigate issues limiting reproducibility of the MSE
diagnostic, and refurbish the lower hybrid launcher.


Lower Hybrid System
-------------------

We have completed the inspection of all 68 modules in the LH High
Voltage Power Supply as part of our maintenance program for this supply.
Two of the modules in the supply have experienced localized melting of
the fuse holder components.  We are working with the vendor to
understand and fix this problem.

Design of an 8-way splitter for the 2nd lower hybrid launcher continues.
The latest design will feed two columns of waveguides from each
klystron, with the proper phase shift between columns incorporated in
the splitter.  This new design should greatly simplify the fabrication
and installation of the 2nd launcher.  Fabrication of a prototype 8-way
splitter is planned, and this prototype will undergo extensive low and
high power testing before being incorporated into the new launcher
design. Preparations are being made for more detailed testing of the
4-way splitter prototype with installation of improved diode detectors.
This splitter was successfully tested at high power several weeks ago.

Cabling has been disconnected from the first launcher as we prepare to
remove it from C-Mod and pull it back for inspection and refurbishment.
The forward and rear waveguides will be separated during the
refurbishment, and the rf gasket will be replaced.

Progress is being made on the rebuild of our #117 klystron by the
vendor.  Two of our engineers are making plans to travel to witness the
acceptance tests.


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

E-Port antenna transmission line components were removed from the cell
in preparation for the borescope inspection of the E-left lower TF arm.
The Fast Ferrite Tuner components were also removed from the cell to
make room for maintenance of the D and E-Port stub tuners and
phase-shifters.


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

Olaf Grulke, Ernst-Moritz-Arndt-University, Greifswald, Germany, is
visiting MIT to work again with Jim Terry, Brian LaBombard, and Stewart
Zweben, on edge fluctuations and turbulence on C-Mod.  He will be
working on the analysis of our 2D turbulence imaging measurements and
helping to implement experiments planned for the next campaign. He also
gave a talk on Blob Propagation in Linear Geometry.

Dennis Whyte attended the inaugural Science & Technology Advisory
Committee (STAC) meeting for ITER in Cadarache, France.  The two day
meeting had many presentation from the ITER Organization with respect to
the formulation of a new Baseline design and the ongoing Design Review.
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