Alcator C-MOD  
			Weekly Highlight Report 
			August 5, 1993

Alcator C-MOD has continued to operate this week. Principal physics topics
for this week's runs are Ohmic Confinement, Scrape-off Layer
Characterization, RF coupling.  Most of the experiments this week are being
carried out with limiter discharges, with elongations of 1.2 to 1.3. The
plasma current has been increased to 600kA. 

Transport experiments have focussed on obtaining profile data from a series
of density scans at several current levels. 

The fast-scanning probe has been used to investigate the scrape-off-layer
characteristics in limiter discharges. The probe head contains 4 probes,
three configured as a "triple probe" and the fourth operating as a
conventional voltage-swept Langmuir probe.  In this week's experiment, the
probe was inserted as far as the last-closed-flux-surface. Peak heat fluxes
around 100MW/m^2 were observed. Near the LCFS the SOL profiles shows an
exponential behavior, with a power e-folding length less than 1cm. For this
run, the RF limiter and antenna were retracted to a point well outside the
plasma boundary.

The EFIT equilibrium analysis code (provided by the DIII-D group) is now
running automatically between shots, as part of the MDSplus cycle.
Equilibria at 20msec intervals are stored in the data tree for each shot,
including the quantities required to map diagnostic data onto a common,
flux-based coordinate system for profile analysis.

Today's run is devoted to RF coupling studies. The RF limiter and
antenna have been positioned at their nominal radii, and the plasma
positioned to match to the antenna shape. The transmitter is pulsed at low
power to evaluate the antenna loading.