From: IRBY@CMOD.PFC.MIT.EDU
Date: Tue, 16 Jun 1998 7:48:28 -0400
Reply-To: IRBY@PSFC.MIT.EDU
Message-ID: <980616074828.25a0156e@CMOD.PFC.MIT.EDU>
Subject: Alcator C-Mod Weekly Highlights
Newsgroups: sci.physics.plasma
Organization: MIT


Alcator C-Mod Weekly Highlights
June 15, 1998


Engineering:

Work continues on the TF magnet refurbishment. Cleanup and
polishing of the lower arm and upper core fingers are nearing completion.
The new inductive heating unit is now fully operational.
Tests of the inductive heating technique have produced temperature
distributions that should be acceptable for feltmetal soldering. Full scale
soldering tests will begin as soon as the fixturing is complete. We continue
to fabricate the bus for the full current, full scale feltmetal tests. The
new Rowgowski coils for this test are in house and being debugged along with
the associated amplifiers, integrators, CAMAC equipment, and software.
These coils will allow us to measure the current and current distribution in
each of the four feltmetal pads that make up a TF coil joint.
We continued our progress on the DNB. Testing of the arc sensors
in the beamline was begun and will now be followed by a full
characterization. The hardware interface for communication between the DNB
PLC and the VAX is now completed and ready for a test of the VAX
control and timing software. Design of the interface between the MCL and
the Arc/Fil/Snubber interface was completed. The required circuit boards
were completed as well. Work continued on DNB PLC I/O connections with
completion of connections to the arc/filament/snubber interface and to the
MCL timing section.
Repairs to FMIT#4's input cavity continue. Replacement parts
(teflon tubing) and materials (conducting epoxy) have been ordered. Work
has also continued on the control boards. The DC breaks have been
installed and await construction of their shields.
Bob Ellis from PPPL visited last week to make some invessel
measurements in preparation for the antenna installation. We plan to
bring up the septum, backplate, and wings for installation before antenna
delivery so that diagnostic clearance can be checked. In discussions with
Randy Wilson (PPPL), the antenna schedule is: complete assembly
on the test stand by 6/15, bake out and begin testing by 6/22, and deliver
the antenna by 7/27.

Physics:

Recent detailed analysis of the fast magnetics fluctuations during
different types of H-modes shows the presence of rapidly rotating modes
even when the signals are apparently incoherent. The rotation of these
modes is in the electron diamagnetic (counter-Ip) direction at speeds up
to those observed previously for the highly coherent Fast Edge Modes (350
kV/m equivalent radial electric field). This observation indicates that
the Fast Edge Modes are part of a continuum of magnetic fluctuations, and
supports the view that these speeds are characteristic of all plasma edge
magnetic fluctuations, presumably reflecting the fluctuation convection
within the edge transport barrier.
We have been successful in running ACCOME on an ALPHA machine
with all modules (equilibrium solver, bootstrap current drive module,
and neutral beam current drive and lower hybrid) executing without
error. Work will continue to install TORIC as the ICRF module and
write an idl post-processor.

Travel and Visits:


Rejean Boivin, Jim Irby, Yijun Lin, Earl Marmar, Dmitri Mossessian,
and Thomas Pedersen attended the 12th High Temperature Plasma
Diagnostics meeting last week in Princeton, New Jersey and presented
several posters and one invited talk. These included

Invited talk by Rejean Boivin:
High Resolution bolometry on the Alcator C-mod Tokamak

C-Mod group:
The Alcator C-Mod Diagnostic Complement

T.S. Pedersen:
Edge X-Ray Imaging Measurements of plasma Edge in Alcator C-Mod

D. Mossessian:
Performance of the Alcator C-Mod Thomson Scattering System

J. Irby:
A Two-Color Interferometer Using a Frequency Doubled
Diode Pumped laser for electron density measurements

E.S. Marmar:
Visible radiation Sieve Interferometer Fluctuation Diagnostic

Y. Lin:
Reflectometry Measurements of Density Profiles and Fluctuations in
Alcator C-Mod

---- C-Mod Related posters presented by collaborators included

J. Heard (Auburn):
Temperature Profile and Fluctuation Diagnostic (ECE) for Alcator C-Mod

W.L. Rowan (U. Texas):
CXRS and BES for C-Mod

V.A. Soukhanovskii (JHU):
FUV Spectroscopic diagnostics for radiative divertor studies at Alcator C-Mod
tokamak

C.F.F. Karney (PPPL):
Effect of Reflection on Halpha emissions in Alcator C-Mod Tokamak

D.P. Stotler (PPPL):
Spectroscopic Measurements of Hydrogen Ion temperature during
divertor recombination

R.J. Maqueda (LANL):
The new Infra-red Imaging system on Alcator C-Mod

During the meeting we had discussions with Uwe Schumacher on possible
collaborations with the Institut fur Plasmaforschung, University of Stuttgart.
Topics discussed included reflectometry and spectroscopy.
Martin Greenwald spent last week at GA for the DIII-D 5 year review.
Steve Wukitch and Paul Bonoli met with Alain Becoulet from Tore Supra
along with Prof. Abraham Bers. They discussed recent results and future RF
plans for both Tore Supra and C-Mod.