Alcator C-Mod Weekly Highlights
                August 25, 2008


FY2008 weeks of research operations:
   Target: 15 weeks
   Completed:  15.7 weeks



Physics
-------

Stewart Zweben, PPPL, has continued his analyses of the SOL turbulence
in limiter discharges and his comparisons of the experimental
measurements with the results of the GEMR gyro-fluid turbulence code,
developed and run by Bruce Scott of IPP Garching. The GEMR code was run
to simulate the C-Mod SOL at various fields (2.8 T - 5.4 T) and
densities.  Code results are in partial agreement with experimental
results.

Jim Terry has solicited and received input from the C-Mod group on
possible C-Mod contributions to a list of research tasks identified as
High-Priority by the various ITPA groups and by the ITER
Organization. Many of these tasks are also addressed in C-Mod's recent
five-year plan (2009-2013). The solicitation was made as part of the
USBPO's desire to organize US responses to ITER urgent needs.


Operations
----------

Polarization Index (PI) tests of both the alternator stator and rotor
were performed successfully last week.  These tests measure the quality
of the insulation.  HiPots and current leakage tests of the stator were
also successfully performed.  Finally, an ELectromagnetic Core
Imperfection Detector (ELCID) verified that the core lamination
insulation is in very good condition.  A visual inspection of the rotor
winding slots indicated one piece of slot insulation had migrated
approximately 2 cm since the last inspection.  We are evaluating how to
resolve this issue. Ultrasonic testing of the alternator and flywheel
bearings indicate that one bearing will have to be sent out for
refurbishment.  We have also begun ultrasonic testing of the flywheel.


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

Work documenting the cooling channels of the FPA (final power amplifier)
tube anode for the FMIT transmitters continued.  Changes in the design
of the anode could extend its lifetime.


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

High power testing of a 4-way splitter prototype has begun with
approximately 200 kW of power for 0.5 s successfully handled by the
splitter into matched loads.  A variety of cases with partial or full
reflections at the four waveguide output ports intended to simulate
worst case plasma effects will also be tested.

We continue thermal, mechanical, and eletromagnetic/plasma simulations
of the new launcher.  Work on the new control system also continued.


Diagnostics
-----------

Work continued on the new FRCECE rf unit, and a redesign of the
Wide-View CXRS and BES optical systems at UTex.


Travel and Visitors
-------------------

Last week Stewart Zweben, PPPL, was at C-Mod to discuss the comparisons
of C-Mod SOL turbulence measurements vs. GEM simulations with Jim Terry
and Brian LaBombard, and to continue analysis of these comparisons.

Steve Scott, PPPL, visited PPPL last week to discuss the MSE upgrade
with Mark Smith, Bob Ellis, George Labik and Larry Dudek, all PPPL.
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