From:
irby@PSFC.MIT.EDU
Reply-To:
IRBY@PSFC.MIT.EDU
Subject: Alcator C-Mod Weekly Highlights
Newsgroups:
sci.physics.plasma
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MIT
Alcator C-Mod Weekly Highlights
January 25, 2002
Assembly
of C-Mod continued this week with installation of the lower
TF
arms. Work continued on ICRF, LH MIE,
DNB, and diagnostic systems.
Physics
-------
At the
weekly physics meeting, Robert Granetz presented some initial
results
involving analysis of x-ray tomography of ITB plasmas on C-Mod.
It may
be possible to use the shapes of the reconstructed x-ray emissivity
contours
to measure the q-profile near the axis.
Recent ITB plasmas on
C-Mod
exhibit extremely peaked x-ray emissivity profiles, which
makes
this technique feasible near the magnetic axis (in an earlier study,
on
ohmic L-Mode plasmas, the technique was found not to be applicable).
These
new preliminary results appear to determine elongation near the center
to an
accuracy of +/-0.03, which would correspond to an error in q0 of +/-0.1.
Tomographic
analysis of high performance eda H-Mode plasmas also shows promise.
Operations
----------
Assembly
of C-Mod continued this week with the installation of 6 out of the
20
lower TF arms. All arms are inspected
carefully, hi-potted, and
thermocouple
and voltage tap instrumentation is checked before installation.
Fitup
and testing of the new springplate insertion tool has begun.
We
continued setting up for machining the cylinder this week. Fabrication of
the new
cryostat ports by an outside vendor is on track for a late Feb
delivery.
Development
of the drive amplifier and some small machining operations for
the new
MHD antennas continued.
Lower
Hybrid MIE Project
------------------------
Commissioning
of the HVPS is well underway. The
primary power supply
transformers
were energized to 13.8 kV this week with the modules initially
disconnected. Following this initial test, the modules
were reconnected
and
testing continued. The snubber, voltage
divider, and triax inner conductor
were
hi-potted successfully to 60 kV with low leakage current. Testing of
the
high voltage dummy load wiring is in progress.
Fabrication
of control and protection circuit boards, development of PLC
software,
preparations for installation of the remaining klystron carts,
development
of the phase and amplitude control software, and work on the
water
cooling system all continued this week.
ICRF
Systems
------------
After
achieving very good results with the phase measurements, careful tests
of the
amplitude detection section of the new demodulator board are in
progress. Both the amplitude and arc detector step
response is less
than 1
us. These fast response times will
limit the damage done by
any
antenna or transmission line fault condition to harmless levels.
Machining
of the D and E-Port antenna Faraday shield and the J-Port antenna
straps
are continuing in house.
DNB and
Related Diagnostics
---------------------------
Planning
and design for the initial installation and commissioning of
the RFX
beam is largely complete. We are ready
to start
modifications
to the beam support frame to accommodate the new beam.
Though
not required for beam commissioning, the F-port flange has
been
approved for machining. Information has
arrived from the Budker
Institute
team regarding the interface of the
beam control software
with
MDSPlus. This information will be used
to begin work on the software
that
will transfer the beam parameters to MDSPlus on a shot by shot basis.
The PLC
rack has been cleared of all old cabling, and new wiring is in
progress.
Once the PLC is wired to the cross connect blocks, we can begin
installation
of the vacuum controllers and other rack mounted equipment.
At
PPPL, mechanical/optical work continued on the MSE diagnostic in
preparation
for reassembly and testing next week.
Travel
and Visits
-----------------
Steve
Wukitch, Jim Zaks, Dave Terry, and Montgomery Grimes attended
SOFE
this week in Atlantic City, NJ. Steve
presented an invited talk
on
C-Mod with an accompanying paper. Jim,
Dave, and Montgomery
all
presented posters, also with accompanying papers. Peter Titus,
PSFC
Fusion Engineering and Technology Division, also discussed analysis
results
of our divertor and antennas.
"Results
and Status of the Alcator C-Mod Tokamak", S. Wukitch, B. Beck,
E.
Fitzgerald, R. Granetz, D. Gwinn, M. Grimes, J. Irby, D. Terry, P. Titus,
R.
Vieira, S. Wolfe, J. Zaks, and the Alcator C-Mod Group, MIT-PSFC, and
S.
Bernabei, R. Ellis, L. Gehrig, J. Hosea, D. Loesser, G. Schilling,
J.R.
Wilson, PPPL
"Inner
Divertor Detailed Design and Manufacturing", J. Zaks, M. DeMaria,
B.
LaBombard, R. Granetz, E. Fitzgerald, H. Savelli, P. Stahle
"The
Alcator C-Mod Lower Hybrid Current Drive Experiment Transmitter
and
Power System", M. Grimes, D. Gwinn, R. Parker, D. Terry, MIT-PSFC,
and J.
Alex, Thales AG
"The
Alcator C-Mod Lower Hybrid Current Drive Experiment Low Power
Microwave
and Active Control System", D. Terry, W. Burke, M. Grimes,
D.
Gwinn, J. Irby, N. Kambouchev, R. Parker, P. Woskov
"Disruption
Load Calculations Using ANSYS Transient Electromagnetic
Simulations
for the Alcator C-Mod Antenna", P. Titus
"Alcator
C-Mod Inner Divertor Upgrade Design and Analysis", P. Titus,
J.
Zaks, M. DeMaria, B. LaBombard, R. Granetz, J. Irby, B. Lipschultz,
E.
Fitzgerald, R. Childs, W. Beck, W. Burke, E. Marmar, D. Gwinn,
I.
Hutchinson, R. Boivin
In
addition, work on the Lower Hybrid system being done at PPPL was
discussed
in three papers:
Design
and Engineering of teh Alcator C-Mod Lower Hybrid Current Drive
System",
G.D. Loesser, J. Rushinski, S. Bernabei, J.C. Hosea, J.R.
Wilson,
PPPL, and B. Beck, R. Parker, MIT-PSFC
"A
Third Generation Lower Hybrid Coupler", S. Bernabei, J. Hosea, C. Kung,
D.
Loesser, J. Rushinski, J.R. Wilson, PPPL, and M. Grimes, R. Parker,
MIT-PSFC
"Compact
Probe Design for the Power Monitoring Fromt he Narrow Side of
the
Reduced Waveguide", C. Kung, S. Bernabei, J. Gumbas, N. Greenough,
E.
Fredd, PPPL