Alcator C-Mod Weekly Highlights
			August 31, 2001


Disassembly of Alcator C-Mod continues.  Work also continues on the new
inner divertor, and the ICRF and LH systems.


Operations
----------

All LN2 cooling lines, horizontal port extensions, and most of the magnet
bus components have been removed from the machine. The lower cryostat panels
have been removed.  Both the upper and lower cryostat panels are now available
for modifications that will allow better access to the horizontal ports, and
will add new instrumentation ports.  The stand required to support the
equipment needed to remove the lower drawbars has been installed below the
machine.  The upper drawbars, drawbar pins, and wedge plate taper pins are all
ready for removal.  Measurements of TF and OH joint resistances have been
made and found to be within specs.


Physics
-------

At the weekly physics meeting Bob Granetz discussed the automated between-shot
xray tomography analysis, which was initiated during the most recent run
campaign with the help of former intern Nitya Kallivayalil.  The inversion
algorithm involves the use of orthogonal expansion harmonics to reconstruct
the emissivity; specifically Fourier harmonics in angle and Bessel harmonics
in radius. Due to CPU and disk space limitations, the automatic inversions are
done only every 100 ms throughout the discharge and written back into the XTOMO
tree, but the analysis can be re-run offline for any number of time slices
for shots of particular interest.  As an example, a movie of xray
emissivity was shown at the meeting consisting of 4000 frames showing a
large m=1 instability (data were digitized at 50 kHz) rotating around the
q=1 surface.  Other interesting topics currently being studied include xray
peaking and sawtooth heat pulse propagation during ITB discharges.

Gerrit Kramer from PPPL has completed the modeling of reflectometer wave
propagation in the peaked C-Mod internal transport barrier
discharges.  An appropriate new set of frequencies, allowing the
measurement of turbulent fluctuations inside the transport barrier,
has been chosen, and the relevant hardware has been specified.
A reflectometer upgrade proposal will be presented to the rest of the C-Mod
team in the near future.

Daren Stotler of PPPL has begun neutral transport simulations of the Gas Puff
Imaging experiments that are being carried out on C-Mod in collaboration with
PPPL.  Stotler is using the DEGAS 2 Monte Carlo neutral transport code to
verify that the simulated average location and size of the emission cloud
arising from the gas puff are similar to those observed with the fast visible
camera.  An initial simulation indicates qualitative agreement, confirming
that the descriptions of the plasma and gas puff being input to the code
are valid.


Lower Hybrid MIE Project
------------------------

Work continues on the PLC control and PC interface programs that will be
used to control the LH HVPS.  The dummy load needed to test the
LH HVPS is under construction in our shop.  Work continues on wiring of
protection circuitry, and the layout has begun on the low power microwave
rack.

The contractor continues to install the klystron water cooling system.
Much of the 8" and 6" diameter piping in the basement has been installed.
The brick wall into the power room has been cored for access for the piping.
Some magnet bus components in the power room have been relocated to make room
for the pipe runs.


ICRF Systems
------------

The 9" transmission lines for the D and E-Port antennas on the east cell
wall have been removed in preparation for the cell modifications.

A new commercially available electromagnetic simulation package is being used
to model the D, E, and J-Port antennas, and the J-port antenna mockup.
A comparison of the J-port mockup antenna measurements and simulation has
shown excellent agreement.  This package can now be used to model any
proposed antenna modification.


Inner Divertor
--------------

We expect to have all major inner divertor components in-house by the
end of next week.  A fitup of the entire inner divertor will be done
invessel as soon as relocation work on diagnostics that run under the
divertor is complete.  The old inner divertor has been completely removed
from the machine, and measurements of stud and diagnostic positions on the
inner wall are being made.

A picture of the first fitup of inner divertor backing and c-plates 
together with some tiles can be found at

http://www.psfc.mit.edu/cmod/operations/EngImages/MACHINE/Divertor/Aug31_08.jpg

A view of the back of the divertor assembly can be found at

http://www.psfc.mit.edu/cmod/operations/EngImages/MACHINE/Divertor/Aug31_10.jpg