Alcator C-Mod Weekly Highlights
                   June 14, 2010


Fy2010 weeks of research operations
    Base Target: 13 weeks
    Base Completed: 9.7 weeks
    ARRA Target: 5 weeks
    ARRA Completed: 5.0 weeks
    Plasma Shots: 1630



Operations
----------

All in-vessel work including documentation, inspection, and diagnostic
calibrations were completed last week, and Alcator C-Mod was pumped down
on Friday morning.  Following an initial leak-check, during which two
leaks were discovered and sealed, the vessel is now undergoing a 120 C
bake that will continue for approximately ten days.  In-vessel close-up
pictures may be found at

http://www.psfc.mit.edu/research/alcator/photos/cmod_images.php?subdir=/INVESSEL/2010%20Close%20up

On Monday June 7, the new database server was put on line replacing the
existing six year old machine.


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

The lower hybrid launcher radial position drive system has been
calibrated and mechanical stop positions set.  Preparations for the next
campaign included development of rf probe calibration routines, work on
both the Transmitter and Coupler Protection Systems (TPS, CPS), and
modifications to the PLC routines needed for the new launcher.


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

Successful operation of the ICRF Breakdown Experiment was demonstrated
during the C-Mod up-to-air period.  Copper, stainless steel and
molybdenum samples were tested with and without a magnetic field
parallel to applied rf electric field. All samples conditioned to a
voltage breakdown threshold when a magnetic field was applied.  Samples
did not reach a threshold without a magnetic field, reaching the maximum
voltage available from the rf source without breakdown.  Future work
will quantify the relative breakdown thresholds among several samples.

The tuning of FMIT#4 in preparation for the next campaign has been
completed with approximately 1.8 MW delivered to the dummy load.  Power
tests of the FMIT#1 and FMIT#2 transmitters still remain to be done.


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

Over the course of the recent machine opening, five coils used as part
of the fast magnetics diagnostic have been brought back into operation.
These coils are part of a set of nineteen that are used for toroidal
mode number identification for both low- and high-n.

Controllers for the GPC and GPC2 grating angles have been replaced and
tested.  Angles were recalibrated optically.  This restores flexibility
in selecting frequency ranges on these ECE instruments.  The H-port ECE
systems, which also include a Michelson interferometer, are being cooled
down, pumped and readied for operation.

The 110GHz reflectometer channel has been replaced by a new 112GHz
heterodyne system with new components.  The system has been reassembled
on the 110GHz system board and a new I/Q circuit has been designed and
built in the same chassis.  The new I/Q circuit will bypass the IF
down-conversion stage of the previous channel, and if it works well
during the next campaign, we plan to apply similar modifications to the
other fixed frequency channels.


Travel and Remote Participation
-------------------------------

Arturon Dominguez was at PPPL last week working with Gerrit Kramer and
Jay Kung building and testing the RF and I/Q circuits for the new 112
GHz reflectometer channel.

Perry Phillips, UT-FRC, was at MIT last week and worked with Ron Parker
to define the data acquisition unit needed to upgrade the FRCECE and
prepare the diagnostic for the upcoming campaign.

On June 8 and 9, several members of the Center for Plasma Edge
Simulation (CPES) visited the PSFC in order to initiate the modeling of
C-Mod discharges. C.S. Chang, Seung-Hoe Ku and Gunyoung Park, all of
NYU, and Alexei Pankin of Lehigh U.  met with C-Mod scientists to
discuss modeling needs and to make a plan for addressing the FY10 and
FY11 OFES joint milestones in scrape-off layer heat flux and H-Mode
pedestal physics. While on site, the CPES team obtained initial modeling
results of C-Mod discharges using both the XCG0 and XGC1 codes. XGC0 is
used to model interpretively the transport and profile structure of the
pedestal and scrape-off layer in H-mode. XGC1, which simulates
electrostatic turbulence in diverted tokamak plasmas, is being applied
to L-mode and I-mode cases.

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