Subject: Alcator C-Mod Weekly Highlights
Alcator C-Mod Weekly Highlights
April 26, 2002
Assembly of Alcator C-Mod continued with the installation of upper cooling
lines, coax connections, curved bus, and port extensions. We continued work
on ICRF and Lower Hybrid systems, and invessel installations. An FFOC meeting
was held at MIT on 4/24.
Paul Bonoli and Eduardo D'Azevedo of the Computer Science and
Mathematics Division at ORNL completed a series of numerical
simulations of mode converted ion Bernstein waves in the Alcator C-Mod
tokamak. In this work the number of poloidal modes used in a spectral
representation of the ICRF electric field was increased from 161 to 255
and then to 511 modes. In the 511 mode simulation, the spectral
coefficients used to reconstruct the electric field were found to be
converged on every flux surface in the plasma. These simulations were
done by D'Azevedo on a single Power4 Node of the IBM SP at ORNL using
31 threads. The 511 mode simulation required 11.5 CPU hours. Work is
now on-going at MIT and ORNL on a fully parallelized version of the
matrix solver used in these simulations. The work will be done by
D'Azevedo, John Wright, and Paul Bonoli as part of the RF Sci-Dac
On Wednesday, a meeting of the FFOC (Fusion Facilities Operations
Committee) was held at MIT to discuss issues related to 21 weeks of
operation for DIIID, NSTX, and Alcator C-Mod during our FY2003 campaigns.
Availability of personnel, spare components, safety issues, and general
operational plans and scheduling were discussed. Peter Perterson attended
from GA. Al Von Halle, Gary Oliaro, and Mike Williams came from PPPL.
Catherine Fiore, Martin Greenwald, Ian Hutchinson, Jim Irby, Earl Marmar,
Miklos Porkolab, Josh Stillerman, David Terry and Steve Wolfe represented
MIT. Warren Marton and Esther Ku attended from DoE.
Assembly of C-Mod this week involved installation of the curved bus that
feeds current to the coils from the bus tunnel, installation of upper TF
cooling lines and cooling panels, and installation of several more
horizontal ports (7 of 10 now installed). The scheduling for installation
of the remaining horizontal ports is now determined by the progress of other
installations that must be completed before the ports can be installed.
TORVAC, the Alcator C-Mod pumping station, has been installed on the
H-Hor flange and will be wired up and tested over the next few days.
We continue to bring the C-Mod computer cluster back online as well as the
various data acquisition highways. The CAMAC engineering highway is now
ready for operation.
The diesel generators that provide emergency backup power for C-Mod systems
in the event of a power failure have been brought into operation and
tested. All the equipment required to auto start the generators and properly
switch them online has also been tested.
The 1200 C bake of the BN tiles has been completed and the oven is now
being cooled down. We expect the tiles back on-site by early next week.
Cleanup and polishing of the D and E port antenna boxes is complete and
the Faraday shields are invessel ready for installation. Installation of
the LH cooling lines displaced the ICRF coax that ran along the east wall
of the cell. Re-installation of the coax along a somewhat higher path is
now in progress.
We continued testing of the new boards needed for the diagnostic, control,
and fault systems. Fabrication of rack hardware also continued.
Lower Hybrid MIE Project
A Status Review meeting of the C-Mod Lower Hybrid launcher project was
held at PPPL on 4/25. Ron Parker and Miklos Porkolab came from MIT;
Stefano Bernabei, Joel Hosea, Doug Loesser, Gerd Schilling, Skip
Schoen, and Randy Wilson attended from PPPL.
The following components are now at PPPL: Couplers, coupler flanges,
shroud assembly, interface flange, rear mating flange, bellows flanges,
transition box, Helicoflex vacuum seals, port extension, ceramic brick
test pieces, and ball screws. These were shown to the meeting attendees.
The following LH components are expected to be delivered to PPPL in the
coming weeks: High strength bolts (4/26), prototype gaskets (5/24), support
members (5/30), forward stacked waveguide (6/1), ceramic windows metallized
(6/5), and vacuum bellows (6/15).
The following LH procurement packages are in preparation at PPPL: Rear
stacked waveguide, high power phase shifters, dummy loads, and WR-187 elbows,
tees and straight sections.
The following LH activities are in progress at PPPL: Fit-up and design
modification on delivered sub-assemblies, prototype validation, ceramic
brick dielectric constant measurements at 4.6 GHz, RF gasket design, and
prototypes for the final coupler braze.
At MIT, the high-pressure water cooling system has been checked out with
full flow through all of the 12 available klystrons. A flow rate of at
least 60 gpm was achieved in each klystron at a differential pressure
of 73 psi.
The water cooling and gas systems for the DNB made progress this
week. The water cooling system hardware has been completed. Proper flow
rates have been measured through the DNB and these rates will soon be
recorded via PLC. Components are being fabricated for the gas system.
Quotes are being requested for the new LN2 feedline for the DNB and
The MSE optical can has been successfully fitup invessel and we are now
preparing for alignment and calibration. The edge CXRS telescope has also
been successfully fitup invessel along with its shutter.
Travel and Visits
Paul Bonoli attended the 2002 International Sherwood Theory Conference
in Rochester, NY, from April 22-24, 2002. He gave a poster presentation
entitled "Fully Converged Solutions of Mode Converted Ion Bernstein
Waves in Toroidal Geometry".
Ron Bravenec, UTexas, arrived at C-Mod Monday and has helped with the
MSE/BES periscope installation and subsequent optical system modifications.
He also installed an overhead rack in the DNB diagnostics area for
the CXRS and BES fiber corrloks.
Miklos Porkolab and Ron Parker attended the Furth Memorial Event at the
Princeton Plasma Physics Laboratory on Thursday, April 25. On the same
morning, they participated in an internal review of the Lower Hybrid launcher
design for C-Mod. They also had a tour of the fabrication laboratory and
participated in detailed discussions regarding fabrication processes and
procedures. Good progress was noted in regard to the launcher fabrication