Newsgroups: sci.physics.plasma
From: IRBY@CMOD2.PFC.MIT.EDU
Organization: MIT
Subject: C-MOD Weekly Highlights


Operations continued last week on Alcator C-MOD. Four run days were
scheduled, but only approximately 2.5 run days were completed because of a
problem with the cryopump gatevalve. The machine was backfilled with
helium on wednesday afternoon to fix the problem. The machine was then
baked and ECDC cleaned with runs beginning again friday morning. Despite
the problem, useful physics runs were completed - including the
commissioning of the second ICRF system on friday. The machine will be run
one additional day this week to help make up for the lost run time.

During the tuesday run the creation of an open or flat-plate divertor
equilibrium was achieved. The gaps between the inner wall and antenna
were very well controlled as were the strike points. Extensive probe
data was taken while sweeping the strike points.

The new E-port antenna was brought into operation during the friday run.
The primary objectives for this run just included tuning and conditioning the
antenna. However, more than 500 kW of power was coupled to the plasma by
the end of the run day. More conditioning will be carried out during the
upcoming run week, with another dedicated RF run scheduled for thursday.

The neutral particle analyzer (NPA) installed in F port is now operational.
Located at the midplane of the tokamak, the analyzer measures escaping
neutral flux which gives information on the ion distribution function through
the charge-exchange process. Ion temperature can be measured for both
hydrogen and deuterium simultaneously. Tail ions produced by RF heating can
also be studied, by looking at the energy spectrum. First results indicate
ion temperature of the order of 1 keV, consistent with measurements
done by other diagnostics. Also measured is the H(ydrogen) to D(euterium)
ratio, which is important in RF heating studies.

Roger Richards from Oak Ridge National Laboratory, and Daren Stotler
and Roger Vesey from PPPL visited last week.