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
May
31, 2002
First power tests of the Alcator C-Mod magnets were
conducted this week.
We continue work on the DNB, ICRF systems, and
diagnostic installations.
Physics
-------
At
the Physics Meeting J. Snipes presented a summary of his collaboration
with
JET Task Force S2 where he participated in experiments on JET the
week of
13 - 17 May attempting to feedback control the q profile in real
time with
LHCD, working with X. Litaudon and D. Mazon of
CEA-Cadarache. Some very
interesting
results were obtained controlling the q profile with LHCD through
a
special matrix controller with coefficients for five radial positions in
the
q profile. As the current penetrated, q
dropped below the requested
profile causing the LHCD feedback to turn on
and within a few seconds, the
q profile was brought back to the requested
values for a change in q of
about 0.5 with up to 1.7 MW of LHCD. This experiment was only a first attempt
to demonstrate real time feedback control of the q profile with
LHCD
under simplified low density (1.2 x 10^19 m^-3) conditions. More
work needs to be done to demonstrate
substantial control of the q profile under
reversed or optimised shear
conditions with combined ICRF, NBI, and LHCD with
strong internal
transport barriers. Nonetheless, this
was a very promising
first step in the direction of steady-state advanced
tokamak operation.
Operations
----------
On
Thursday liquid nitrogen cooling of the magnets and tokamak structure
was
begun, following commissioning of the vessel heater system.
Power tests
were begun on Friday with all EF supply and EF1 commutation
tests
completed successfully. Following the
power tests, a 120 C bake of
the vessel was begun. The bake, together with ECDC wall
conditioning will
continue until the middle of next week at which point
power testing of
the TF and OH supplies will begin.
Lower
Hybrid MIE Project
------------------------
Work continues on
the commissioning of the lower hybrid HVPS.
The supply has
now passed two wire tests indicating that it can be
shut down quickly
enough to keep total dissipated energy below 15
Joules. Dummy loads and
their
associated water cooling lines are being installed on the klystron carts.
ICRF
----
Work
on the new control system for the phase shifters and stub tuners
is nearly
complete. Detailed s-parameter
measurements of the D, E,
and J-antennas are being made in preparation for
vacuum conditioning
and plasma operations.
RFX DNB
-------
The
RFX DNB is back in operation and conditioning will continue
through the
remainder of this week The fueling
system is complete,
leak checked, and installed. It supplies the two
separate pressures
required by the ion source.
Diagnostics
-----------
Work
continues bringing back online diagnostics needed for plasma
operations.
Travel
and Visits
-----------------
Gerrit Kramer, PPPL, was at MIT 5/29 and 5/30, completing hookup
and
checking out the new 130 and 140 GHz reflectometer edge fluctuation
channels. Dale Meade, also PPPL,
was at MIT 5/30 for discussions on
FIRE-relevant double-null divertor
experiments planned for the coming
run campaign. Discussions were held with Bob Granetz,
Steve Wolfe,
Joe Snipes, Amanda Hubbard, Earl Marmar, Paul Bonoli, and
Miklos
Porkolab.