Alcator C-MOD  
			Weekly Highlight Report 
			August 18, 1993

Alcator C-MOD is continuing the second block of runs in our Phase I
Experimental program. Operation is becoming much more reliable as the
campaign moves into its fifth week. 

Last Friday's discharge development run was successful in producing well
separated single-null (lower x-point) equilibria in which the upper null is
outside the vacuum vessel, and the minimum gap (to the inner wall) exceeded
2.5cm.

The ICRF coupling studies are continuing to operate in piggy-back mode, and
is now routinely injecting power on essentially every shot. Over 50kW has
been launched into the plasma. The tuning procedure has been established,
and excellent matching is observed. 

Tuesday's run was the first devoted to pellet injection studies. Two sizes
of deuterium pellets were successfully used to fuel the plasma,
individually and in combination. The pellet injector operation was very
reliable over the course of the run, firing pellets on all 19 shots where
it was requested (On two shots, the pellets failed to reach the plasma
indicating  a minor problem with alignment.)  Pellet fueling enabled us to
reach the Greenwald limit at a current of 0.4MA. On several shots there was
prima facie evidence that we had entered the enhanced ion confinement
regime following pellet injection. We also saw clear signatures of a
"snake" ( persistant m=1 perturbation) on both xray and density
diagnostics.  Tuesday's run was also used to test operation with cold
walls; the vessel temperature was lowered to -40C for the entire run, as
opposed to our typical operating temperature of +10C.  Reliable operation
was obtained with no obvious detrimental effects. 

Wednesday's run is being devoted to a study of confinement as a function of
elongation at constant current and density.