From: irby@PSFC.MIT.EDU
Subject: Alcator C-Mod Weekly Highlights
Newsgroups: sci.physics.plasma
Organization: MIT


Alcator C-Mod Weekly Highlights
September 2, 2003



The alternator inspection is nearing the point after which reassembly can
begin. Work on ICRF and lower hybrid systems continued.


Physics
-------


The next C-Mod Ideas Forum will be held on September 10-12 at MIT. The
Ideas Forum aids in planning the FY04 C-Mod Operating Campaign. The
purpose of the forum is to provide an opportunity for presentation of
specific ideas appropriate for experiments during C-Mod's 2004 run
campaign. As usual, the Forum will be open to all interested parties,
including current and potential future collaborators. Presentations
will consist of five-minute, no-more-than-three-slide, talks
summarizing the basic idea and benefits of each proposed
experiment. The meeting will be available for remote participation and
presentations. See

http://www.psfc.mit.edu/people/terry/Ideas_Forum_2003/Ideas_forum.html

for details. The deadline for initial submission of ideas (title only)
is Wednesday, September 3.

Peter Catto is investigating a mechanism whereby heat flow terms in
the neutral viscosity allow a stationary tokamak plasma to push off
the wall thereby imparting momentum to the plasma. The magnetic field
of the tokamak breaks symmetry by requiring there to be a
Pfirsch-Schluter toroidal heat flow to balance the diamagnetic heat
flow. The heat viscosity terms allow the neutrals to push off the wall
and spin the plasma at the edge toroidally in the counter-current
direction.


Alternator
----------

Ultrasonic inspections of the alternator rotor continued last week.
Reassembly of the rotor components should be completed this week after
which hi-pots of the rotor will be performed.


Lower Hybrid Systems
--------------------

Assembly of the Forward Wave Guide (FWG) is going well at PPPL, with
both the upper and lower waveguide stacks now reassembled. The upper
FWG will be transported to MIT early next week for high power RF
testing. The lower FWG will be tested at PPPL at low power levels.
The shroud assembly has been completed, and new interface flanges have
been delivered. As reported last week, a demonstration of chemical
removal of a coupler window on a prototype, i.e. etching of the braze
material, was successful. The vendor will begin window removal from
actual C-Mod couplers this week. An order has been placed for a full
set of replacement windows, due 9/28. The first ceramic material
samples are expected at PPPL next week for thermal expansion and
dielectric tests. Titanium material has been received for the
fabrication of a new coupler, if needed.

We have completed reassembly, and successfully tested to full power,
the waveguide run from the klystrons in the cell to the high power
testing area. This system is ready to be used to test the FWG stack
when it arrives from PPPL.

We have received the circuit boards for the SFOL receivers. A board
is being populated for testing. A network analyzer is being used to
calibrate the lower hybrid phase and amplitude control system, and
hardware and software is being developed to automate this process.
Work continues on the PLC programs and hardware required to maintain
the launcher at a constant temperature. This system will protect the
launcher if faults in the C-Mod heating/cooling systems cause a large
variation in vessel temperature.


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

FMIT #2 has been operated between 78.8 and 80.2 MHz to gather
gain-bandwidth product information. This data will be used to
determine if matching to the plasma could be improved with real-time
frequency control of the source. Dummy loads are being refurbished
and prepared for use. We continue the design and simulation work
required to operate the J-Port antenna at 50 MHz. Upgrades to the
control system for FMIT #3 and #4 are underway that will allow
improved dummy load and low level RF chain testing to be implemented.
These upgrades also improve plasma operation capability.


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