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 14, 2000


Invessel, RF, DNB, and power system work continued last week. Pumpdown,
startup of vessel heater and cryo systems, and leak checking are all
scheduled for the next few days.


Engineering:

The DNB power systems were brought into operation into the beamline last
week. This operation completes our final milestone for the DNB approximately
one month early. In addition, a 25 kV beam at approximately 2 amps was
extracted just to test all the HV, interlock, control, and protection
circuitry. Some ground loop problems were discovered during the test that
will be fixed over the next few days. We are also in the process of resolving
DNB personnel safety issues so that people can be allowed in the cell
during DNB testing. During the first few days of operation we have not allowed
anyone in the cell when high voltage was applied to the beamline.

We are moving quickly on invessel work and expect closeup and pumpdown
this week. Alignments, invessel cleanup, and documentation and inspections
continue. The new rangefinder retro-reflectors are installed as are the
tile support plates they look through. The alignment of the new retro-
reflectors has been checked with a telescope from outside the C-Hor port
and looks acceptable. Preparations are being made for alignment of
the tangential two-color-interferometer which will occur as soon as the
C-Hor flange is back in place. Invessel alignment and calibration of the
visible continuum array was completed. The input periscope design has been
changed, and the new system has increased light throughput, which will allow
for improved time resolution. The system mirror has been slightly reoriented
so that the camera view goes farther out into the scrape-off, well into
the shadow of the outboard limiters.

Invessel ICRF antenna activity is complete including extensive measurements
of antenna tile locations and careful alignment checks. Measurements of and
possible adjustments to the external resonant loops coupling the antenna
current straps to the transmitters are in progress. One of the loops
for the older D- and E-port antennas had previously been found to be
off-resonance, and the recent J-port antenna modifications have
changed its electrical characteristics sufficiently to necessitate a
recheck. PPPL RF fault detectors in use at C-Mod are being modified
for faster response times, and remaining transmitter upgrades are
continuing. A thermocouple has been added invessel to measure the
temperature of the E-port antenna with the boron nitride upper and
lower tiles. The #1 and #2 transmitters FPAs, which were disassembled during
the maintenance period, are nearly back in service, as checks of the FPA
crowbars have been completed, and tests of the screen crowbars are
underway.

The MSE optics repair and calibration will be completed by Tuesday. A lens
assembly motion restrainer will be added from outside the vacuum
vessel early in the week of 2/14.

We are finishing up work on several engineering systems in preparation for
vacuum conditioning and eventual plasma operation. Improvements to the
GN2 seals on the bus tunnel, cryostat, sump, and valve manifold box have
been completed. Work on the heater system to protect the connectors from
water intrusion will be complete by pumpdown, at which point checkout of the
heaters will begin with a 35C "bakeout" for a few days. All bus
instrumentation has been refurbished and checked out. Improvements to
the Cryo system wiring have been completed. Calibrations to the 13.8 kV
instrumentation are also nearly complete. Engineering data is flowing
again between our control computers (PLCs) and our VaX cluster.


Physics:


On 2/7 and 2/8 of last week a Program Advisory Committee Meeting was held
at MIT. Ben Carreras of Oak Ridge chaired the committee, and the other
members are Philip Efthimion and Ed Synakowski of PPPL, Ray Fonck of U. of
Wisconsin, Tony Leonard of DIIID, Mike Mauel of Columbia, and Claude Gormezano
of Frascati. John Willis and Rostom Dagazian from OFES attended the meeting.
Talks were given by Alcator C-Mod personnel and our collaborators covering
nearly all aspects of the C-Mod program; the agenda included:

Welcome -- Porkolab

Introduction and Overview -- Marmar

Advanced Tokamak Program:
Goals -- Parker
Modeling -- Bonoli
FY2000 Experiments -- Marmar

Transport:
Overview -- Greenwald
Core Transport -- Rowan
Pedestal Physics -- Hubbard

Divertor/Edge:
Scrape-off Layer Transport -- LaBombard
Long Pulse/AT Divertor Issues (particle and power) -- Pitcher

ICRF Physics:
Overview -- Wukitch
Heating, Flow and Current Drive -- Schilling

MHD -- Granetz

Performance Enhancements -- Snipes

Schedule and Run Planning -- Wolfe

Experimental Facility Status, Hardware and Diagnostic Upgrades,
Long Pulse Operation -- Irby

Lower Hybrid RF:
Hardware Plans -- Bernabei
Preparation and Schedule -- Irby

Budget -- Marmar/Keating

In addition, a session in which questions asked by the PAC were answered
was held on the second day.

A quarterly review was held on February 9. Rostom Dagazian from OFES discussed
various aspects of the C-Mod program with Ian Hutchinson, Earl Marmar, Jim
Irby, Bill Rowan, Dave Terry, Steve Wukitch, Gerd Schilling and Joel Hosea.
The discussions centered on the status and near term plans for the diagnostic
neutral beam and its associated diagnostics, and on the ICRF systems.


Travel and Visits:

Barrett Rogers of U Md visited to deliver a seminar on edge
turbulence. Discussions with members of the C-Mod team included
future plans for collaboration on non-linear fluid simulations and
gyro-kinetic stability calculations.

Joel Hosea, PPPL, came 2/7-2/9 to discuss Lower Hybrid program issues and
our coming ICRF startup. Stefano Bernabei also came from PPPL to participate
in LH program discussions (as well as give a talk at our PAC meeting).

Rejean Boivin was in Quebec city for the first (on site) planning meeting
for the APS-ICPP meeting in next october. Plans were made for the
outreach day and space allocation.