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
February
9, 2001
The
Alcator C-Mod Program Advisory Committee Meeting took place
last Monday
and Tuesday. On Wednesday and Thursday
a Preliminary
Design Review for the Lower Hybrid Project took place. We continue
to work on the J-Port ICRF
antenna redesign, and the Lower Hybrid project.
PAC
Meeting
-----------
The Alcator C-Mod Program Advisory
Committee met at MIT on 2/5 and 2/6.
Talks were given by the C-Mod staff
detailing the physics results and
physics and facility goals. On the committee were Ben Carreras
(ORNL),
Philip Efthimion (PPPL), Ray Fonck (UW), Claude Gormezano
(Frascati),
Tony Leonard (GA), Ed Synakowski (PPPL), and Mike Mauel
(Columbia).
Rostom Dagazian attended from DOE. The committee was asked to evaluate the
overall progress,
priorities and balance in the present C-Mod program.
They were also asked
to assess the links between experiment and theory,
and our progress and
plans for the ICRF and DNB programs.
Lower Hybrid
Project
--------------------
On 2/7 and 2/8 of this week the
Lower Hybrid PDR was held at MIT.
The
review panel consisted of Tim Bigelow (ORNL), Tom Intrator (LANL),
Nevell Greenough
(PPPL), Steve Knowlton (Auburn), and Claude
Gormezano (Frascati). Both T.V. George and Rostom Dagazian
represented DOE
at the review. The
MIT group presented both overall plans and some details
of the power,
control, timing, and data acquisition systems.
They also
presented results from the klystron test stand indicating
the status of
all 16 tubes. The
PPPL group presented extensive details of the
launcher design.
We
have now run some preliminary control loop tests on the NI PXI controller
for LH that will be used to control the amplitude and phase of the
klystrons. Using the standard PID, we achieved 8
channels of control with
a 3 kHz sampling rate. Upon optimization, we were able to reach a 4.4 kHz
sampling
rate.
ICRF Systems
------------
A great deal
of work was done on the J-port antenna modifications this
week. Nearly all machining of the antenna back
plate was completed.
Prototypes of the new stripline components have been
machined and assembled.
We are currently investigating the most efficient
way to machine the final
inconel-625 components.
We are
developing an acoustic arc detector for the ICRF
system to locate arcs in
long sections of transmission line.
The process of finding arcs has
generally been a very time consuming
task that the new detectors should
alleviate. We now have two
receiver
channels in operation. A
generator that can produce from 2 to 20 J
arcs has also been brought into
operation for testing the detectors.
The test transmission line is now
being assembled.
Maintenance and refurbishment of all four
transmitters continue in
preparation for the next plasma operating
period.
DNB
---
After extensive improvements
to the gas fueling system, the water component
in the beam has been
reduced to less than 4%. Preparation
for the PAC and
the upcoming DNB Review has precluded work on reducing
this component
further. The time
variation of the component mix together with the beam
width have been
extracted from data taken during plasma discharges from last
December. They indicate that both the width of the
beam and the full energy
component degrade slightly during the beam
pulse. We are following
up on this
result as a path to better performance as beam operation
continues this
week.
Inner Divertor
--------------
The
backing plate components have now been rough EDM cut and are being
prepared
for machining of the holes and keyways.
One hundred reworked tiles
arrived in-house and are being checked
through Q/A. These tiles, which
originally
did not meet spec, now appear to be satisfactory. Tile
support plates continue to arrive. The high strength bolts for attaching
the
C-plates to the backing plates have been age hardened by a local vendor.
Visitors
and Travel
-------------------
Ron Bravenec (UT-FRC) visited
this week and attended the PAC meeting.
PPPL was well represented at
both the PAC Meeting and the Lower Hybrid
Review. Rich Hawryluk, Ned Sauthoff, Joel Hosea and
Gerd Schilling
attended the C-Mod PAC Meeting this week. Stefano Bernabei, Doug Loesser
and
Skip Schoen also from PPPL made presentations at the Lower Hybrid
Project
Review. Also attending the review from
PPPL were Joe
Rushinski, Joel Hosea, and Gerd Schilling.