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
23, 2001
We continue
to work on modifications to the J-Port antenna, improvements
to the J-Port
fault protection systems, the DNB and related diagnostics,
and the Lower
Hybrid Project.
ICRF Systems
------------
The
J-port antenna modifications have been
designed and the longer lead
items have been detailed. The schedule driver is the manufacturing of
the
new striplines. An aluminum
prototype of one of the striplines was
produced by our EDM vendor, and we are awaiting a second prototype to
be
delivered 2/26. The stripline
return is being fabricated. The new antenna
mounting
hardware prototype has been successfully tested. The Faraday
screen modifications have been tested, and we
will begin to make the final
assembly next week. The vacuum feedthrough ceramics have been reconditioned
and
deburring the outer conductor has begun.
Fault indicator board
construction for the new J-Port fault protection system
is complete and
testing of the board has begun. The
first phase balance board
was also completed this week. Cabling lists are being made up for this
new
system. We also continue to
add instrumentation to make tuning of the
transmitters a more automatic
operation. Eight of eleven new tuning
position
indicators for FMIT#4 have been installed. We plan to have
FMIT#3
and #4 ready for dummy load
testing in early March in preparation for the
upcoming run period. Inspection of FMIT#3 found an intermittent
IPA output
cavity contact with damaged finger stock. The system was refurbished and
reassembled
and will be tested next week.
DNB
---
Automatic
operation of the DNB will be required to fire the large number
of shots needed to fully
condition the beam. Automatic operation
was designed
into the software from the
beginning but has just been tested.
The initial
test was completed by firing many shots with only the
filaments and the arc
in operation.
The latter was discharged into a dummy load. Actual beam
conditioning will begin early next week. The antenna pattern for the high
resolution
ECE system is now being measured. This data will be used in
establishing
the wavenumber limits for fluctuation
data. The saturation seen
in some of the data from the last run was traced
to one set of IF amplifiers
which have since been repaired.
Lower
Hybrid Project
--------------------
We have been working with
MIT and their architects to define the
lower hybrid system water pipe
routing. The result is a recommendation
to
re-route two ICRF transmission lines to make way for the water
pipes.
Details were given to the architects on locations of the water
loads to
facilitate the water manifold design. This water system will provide
approximately 1200
gallons/minute of water at 200 psi to cool the klystrons
and associated
equipment. Work is also proceeding on
the RF cart modifications
and wiring.
Drawings of the lower hybrid launcher have been provided by
PPPL
and are being incorporated into our cell layout drawings to look
for any
conflicts.
Inner Divertor
--------------
Tests
are being performed on stud welding techniques that will be needed to
install
the new inner divertor. One vendor has
slipped about 10 days in
the shipment of 150 upper transition tiles, but
this delay does not affect
our installation schedule. The rear girdle plate procurement is
on
schedule. Holes and slots have
been milled in all the plates using
wire EDM. Machining of the ribs that
key into and restrict motion of the tiles
is expected to start next
week. The C-Plates, the other major
structural
component of the girdle, are being machined as one large ring
that will be
cut apart to form the plates. The machining of the inner radius is complete
and work is
now proceeding to finish turning the outer radius cut.
Tiles, high
strength bolts, and tile screw keepers are being cleaned and
prepared for
installation.
Power Systems
-------------
The
OH2L and the OH2U commutation switch capacitor bank work has been
completed. Work is proceeding on the OH1 bank.
Data
System
-----------
A new high performance server system was put
into service this week to be
used for C-Mod data acquisition and between
shot analysis. The previous
server will now be used to serve the operating
system and user disk files to
C-Mod OpenVMS systems. The new server should
significantly increase the
data handling capabilities of the data
acquisition system. These system
changes
are essential to meet the increased throughput requirements of
new C-Mod
subsystems such as the Lower Hybrid Project and diagnostics with
high data
volume/rate requirements.
Travel and Visits
-----------------
Les
Gereg and Joe Frangpani of PPPL visited this week to help with antenna
modifications
and fit ups and reconditioning the vacuum feedthroughs.