Alcator C-Mod Weekly Highlights
                November 12, 2012


FY2013 weeks of research operations
    Target: tbd
    Completed: 0.53 weeks
    Plasma Shots: 61


Operations
----------

Routine maintenance of engineering systems continued last week.
Preparations are being made for a full inspection of all 13.8 kV power
system breakers.  Maintenance continues on alternator and magnet power
supply systems.


Advanced Outer Divertor
-----------------------

A prioritized list of action items generated by the Preliminary Design
Review has been compiled. A few high priority items include
determination of the best way to secure the A-frame components while
maintaining proper thermal isolation, resolving current shunt pin
galling issues, assessing the strength of threads in the tungsten and
moly tiles, and the addition of baffles to control gas flow out of the
divertor.

Design of a diagnostic package for the outer divertor has begun
including Langmuir probe arrays and thermocouples.  Heater cabling and
feedthrough design and selection is underway.

Plans are being made, in collaboration with PPPL, to continue testing of
shunt pins, heaters, and spherical bearings.

Thermal and electro-magnetic analysis continues.


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

The FMIT#3 output cavity loading components have been reinstalled, and
tests indicate that repairs were successful.  FMIT#3 and FMIT#4 have been
operated into vacuum to help localize the source of the faulting that
limited performance of the Field Aligned Antenna.  These tests indicate
that the FMIT#4 phase shifter or output transmission line is most likely
the problem.  Disassembly of transmission components near this location
will need to be done to identify the exact location.

The last four of six new Fast-Ferrite-Tuner units arrived on-site last
Friday.  They have been moved into the power room to be unpacked and
inspected. The tuner that developed a water leak (one of the first two)
is being prepared for shipment back to the vendor.


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

The LH3 bijunction two way splitter prototype assembly has been tested 
at low
power with a network analyzer.  The performance was found to be
excellent, with power delivered equally to each output waveguide.
Phasing between the outputs was measured at 91 degrees compared to the
design specification of 90 degrees.  The bijunction input is now
connected to klystron 11 and a high power water load is attached to each
output of the bijunction in preparation for high power testing.

The LH FFT work continues.  The ends of the ferrite were rounded to
reduce losses in the stub tuning network.  The decision was made to
incorporate an IQ detector measurement in the FFT control algorithm.
Multiple local minima in the control space made an algorithm based on
magnitude of the reflected power alone infeasible.

Tests are underway to assess the performance of new fast thermocouples
in the return leg of the klystron collector cooling system. Erratic
signals from two of the collector thermocouples caused TPS faults during
the initial tests. Debugging of these signals has begun.


Remote Participation, Travel, and Visitors
------------------------------------------

Amanda Hubbard participated remotely in the Research Councils UK (RCUK)
Fusion Advisory Board meeting November 5-6.

John Rice gave a talk on 'Particle, Heat and Momentum Transport in
Alcator C-Mod Tokamak Plasmas' at the Dartmouth College physics
colloquium on Nov.9.

Robert Granetz gave an invited talk at an MHD workshop (and Joint
US/Japan meeting) on massive gas disruption mitigation for ITER. The
workshop was held at Columbia University in New York.

John Wright hosted the visit of Takuma Wakatsuki from the University of
Tokyo during the week of November 5-9. This visit is part of an on-going
US-Japan Collaboration in which Takuma and John have been using the
TORLH-CQL3D code suite to simulate hard x-ray emission during lower
hybrid current drive experiments in the TST-2 Spherical Torus
Device. The current work focused on the simulation of experiments that
used a dielectric loaded waveguide array to couple LH power at 200 MHz
into TST-2 plasmas.  They also worked on simulations of these
experiments using the Genray-CQL3D code suite. During his visit Takuma
also had extensive discussions with Syun'ichi Shiraiwa and Gregory
Wallace concerning his experimental results and LHRF system installation
on TST-2.

Tom Fredian and Josh Stillerman traveled to Padova, Italy for
discussions on MDSplus future development plans. They met with Gabriele
Manduchi and Adriano Luchetta to discuss the data system for two ITER
test facilities called SPIDER and MITICA being constructed in Padova.
Tom, Josh and Gabriele discussed plans for new MDSplus enhancements such
as:

      - An improved LabView interface to be released soon.
      - Support for storing "opaque" binary data.
      - Support for storing jpeg and mpeg image data.
      - New "plugin" data storage layer providing a mechanism for
        developers to add support for utilizing alternative storage
        technologies such as cloud storage and hdf5.

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