From:
irby@PSFC.MIT.EDU
Reply-To: IRBY@PSFC.MIT.EDU
Subject: Alcator C-Mod Weekly Highlights
Newsgroups:
sci.physics.plasma
Organization: MIT
Alcator C-Mod Weekly
Highlights
March
16, 2001
We continued
to maintain transmitters and power systems, develop Lower Hybrid
systems,
and fabricate new J-port antenna components.
Work is proceeding
on improvements to the ICRF control system. Work continues on the new
inner
divertor. A design review of changes to
the J-Port antenna was held.
ICRF Systems
------------
We
expect all inconel components for the J-Port antenna modifications to
be
in-house by early next week. Some
machining and finishing in our shop to
the components will be required
before they can be welded, plated, and
baked, at which point they will be
ready for installation. E-beam
welding
tests are being done to inconel samples, and fixturing is being
developed
to support the welding of the actual components. Our hydraulic press was
used to
successfully bend the two long inconel striplines into the proper
shape. Several fiber views of light from possible
plasma discharges around
the striplines are being planned. We also expect to make a pressure
measurement
at this location. Designs for the fiber periscopes, and pressure
sampling
tube are being produced. New holes in
the horizontal flange for
these measurements will be drilled over the next
few days. Components for
the
diagnostics are being made in-house.
On Wednesday, 3/14, a final
J-Port antenna review was held via video
conference. Steve Wukitch presented details of the
problems we had with
the antenna, and the changes we are making to allow
full power performance
during the next run period. Steve's presentation can be found at
www.psfc.mit/people/wukitch/antreview.pdf
Attending
the review were:
ORNL Phil
Ryan
Rick Goulding
PPPL Gerd Schilling
Bob Ellis
GA Bob
Pinsker
C-Mod Steve
Wukitch
Rejean Boivin
Jim Irby
Peter Titus
Bruce
Lipschultz
Brian
Labombard
UTexas Perry
Phillips
There was general agreement on the antenna
modifications. There was
also
strong agreement that phase measurements with fast time response
are
essential. These measurements are being
implemented, and
the antenna will not be operated without them. Since the modifications
require
supporting the antenna at the top and bottom from the center of the
antenna,
a concern was raised about thermally induced stresses.
FEA analysis of the
antenna performed following the review indicates that
these stresses are
in fact small.
We continue to perform maintenance and inspections
of the transmitters.
FMIT#3 was brought up to full power into a dummy load
this week. However,
during these
tests, a new intermediate power amplifier tube failed after
approximately
10 hours of operation. An older spare
tube is being installed
and the new tube is being sent out for
evaluation. Extensive tests of
the
IPA protection circuits and cooling systems indicated all were
functioning
properly.
Diagnostics
-----------
UT-FRC
and U. Idaho personnel are continuing bench measurements to
determine the
precise spatial resolution of the
antenna for the High
Resolution ECE heterodyne system. Based on the initial results, a
new
waveguide with improved resolution was designed at UT and is being
fabricated
at UT for installation prior to the end of the current
down period.
DNB
---
The
detailed shutter design for the CXRS toroidal optics was
completed. Parts for the shutters and their actuation
mechanisms
were ordered with the expectation of delivery next week. Detailed drawings
have been given to
the Alcator machine shop for manufacture.
Lower Hybrid MIE
Project
------------------------
We continue to develop the
active controller program. Work this
week
involved primarily more work on the input/output routines,
together
with another set of routines to set limits for the I/Q detectors.
We
continue to prepare the three klystron carts for operation.
Measurements
are being made in the cell to verify that columns for
the new mezzanine to
support the klystron carts will not interfere with
other equipment in the
cell. A meeting was held on 3/16 to
decide
which port the first launcher would occupy.
Power
Systems
-------------
The machining of the support structure
for the EF1 capacitor bank
has been completed. Signal cabling for ground current monitoring of the
commutation
banks is being installed. We have begun
to setup for testing
and calibration checks of all commutation switch
Rogowski coils.
Inner Divertor
--------------
Inner
vessel wall tiles and support plates were removed this week to
check stud
alignment in preparation for the new inner divertor
installation. Our rapid prototype plastic divertor
components were installed
successfully.
Pictures of the fit-up can be found at
http://www.psfc.mit.edu/cmod/operations/EngImages/CmodImages.asp?ref=/MACHINE/Divertor/
Tiles
and other divertor components continue to arrive.
Travel and
Visits
-----------------
Earl Marmar, Ron Parker, and Miklos
Porkolab attended the DoE
Budget and Planning Meeting March 13 to 15 in
Gaithersburg. Earl and
Ron gave
talks on C-Mod and the LH MIE Project.
The viewgraphs from
these talks can be found at
http://www.psfc.mit.edu/cmod/sciprogram/CMod_Budget_Meeting_Presentation.pdf
Amanda
Hubbard gave a talk at California State
University of Sacramento
on Thursday, 3/15, as part of the APS/DPP
Distinguished Lecturers in Plasma
Physics series, entitled "Understanding and Improving
Energy Transport
in Fusion Plasmas."