Alcator C-Mod Weekly Highlights
               December 1, 2008

FY2009 weeks of research operations:
  Target: TBD
  Completed:  0 weeks


Physics
-------

Plasma instabilities can be stabilized by plasma flow and velocity shear
in tokamak plasmas.  New methods may be needed to generate such
stabilizing flows in ITER and fusion reactors where the torque available
from neutral beams will be low or non-existent.  Strong toroidal and
poloidal flows have been observed for the first time in Alcator C-Mod
during the application of ion cyclotron mode-conversion power in D^3He
plasmas.  These observations are well documented by Yijun Lin and his
co-authors in "Observation of Ion-Cyclotron-Frequency Mode-Conversion
Flow Drive in Tokamak Plasmas", just published in the December 5th issue
of Physical Review Letters, and can be found at

http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PRLTAO000101000023235002000001&idtype=cvips&prog=normal


Operations
----------

We continued to fabricate and test spring-plates for the TF magnet last
week.  Installation of the new TF arm insulation also continued, as did
silver plating of the finger joints, and testing and installation of
vacuum vessel heaters.

A contract has been awarded for re-inspection of the alternator rotor.
This work is expected to begin during the week of December 8.  In
addition, we have chosen two companies, recommended by EPRI, to perform
independent analysis of the non-destructive testing (NDT) data from the
inspection.  Plans are also being made to obtain material samples from
the rotor core, which together with the NDT information, will allow
improved estimates of the rotor lifetime and inspection intervals to be
made.


Lower Hybrid System
-------------------

We continued to procure components needed for the second launcher.
Preparations as being made to anneal and copper plate the components
that will make up the 4-way splitters.  Fabrication continues on the
waveguide sections that hold the vacuum windows.  The first copper
plated splitter continues to undergo a careful inspection following a
successful high power testing program.  Design and installation details
are being finalized for the rf probes and reflectometer channels that
will be installed as part of the launcher.


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

We continued testing of the FMIT#4 transmitter and its new Intermediate
Power Amplifier (IPA) stage.  Preparations continued for installation of
the new IPA stage in the FMIT#3 transmitter.  We are ready to remove the
IPA cavity as the first step in this process.


Travel and Visits
-----------------

Alessandro Marinoni, a graduate student working with Stefano Coda on TCV
at the Centre de Recherches en Physique des Plasmas, École Polytechnique
Fédérale de Lausanne, visited last week. He gave a seminar on "The
effect of plasma triangularity on turbulent transport: modelling TCV
experiments by linear and non linear gyrokinetic simulations."
Alessandro Bortolon, also from EPFL, is visiting during the week of
Dec.2-5 to analyze data from an ITPA joint experiment (1080502014, MP
535a).

Two visiting scientists arrived this week for extended on-site
stays. Olaf Grulke, a long-time collaborator from IPP-Greifswald and
Ernst-Moritz-Arndt-University, has returned for a two week visit. He
will continue his analyzes of edge turbulence in C-Mod. Dr. Matteo
Agostini from the RFX group in Padua, Italy, has joined us for a stay of
four-weeks. He has worked extensively analyzing SOL turbulence
characteristics from different devices, including RFX, TPE-RX (an RFP in
Japan), NSTX, and C-Mod. He will expand his analysis of C-Mod SOL
turbulence.  Stewart Zweben, PPPL, is also on-site this week,
participating in discussions with Drs. Grulke and Agostini.



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