Alcator C-MOD   
			    Weekly Highlight Report  
				October 21, 1993

Alcator C-MOD is now in the sixth week of the current operating period. 
As observed duiring our last campaign, startup and disruption recovery have
become more reliable after the first month of operation, presumably due to the
cumulative effects of discharge cleaning and high-power plasma operation on
wall conditioning.

The ICRF power coupled through the monopole antenna has been increased to over
0.75 MW, with over 0.5MW average power sustained for about a half second. 
Increases in radiated power are less than the injected ICRF. The loop voltage
and Zeff are observed to increase, but not by large factors. No clear evidence
of ion heating has been observed so far. 

Studies of impurity transport scaling, using the laser blow-off technique, 
were carried out for a wide range of densities and currents. These experiments
were carried out in well-diverted single null discharges. Results appear to
be at some variance with those of similar experiments on Alcator C,
particularly with respect to the scaling of the impurity confinement time with
the safety factor q. 

Divertor gas puffing experiments begun last week were continued, including
injection of He through the capillary tubes in the private flux region.  A
neutral pressure gage (Haas gage) located in the divertor region is now
operational. 

The lithium pellet injector is now installed, and was employed for fueling and
as part of the impurity transport studies program. As with deuterium pellets,
when the penetration reaches the q=1 surface snakes are observed in both xray
and density diagnostics. 

Analysis of ohmic plasma confinement at currents up to 1MA indicates that, at
lower densities, energy confinement is often significantly higher than
expected from neo-Alcator scaling. Overall, confinement appears to scale more
strongly with plasma current than with density, in a manner resembling L-mode.
This result must be seen as preliminary, because for this data, from early in
the operation of C-MOD, the wall conditions from some runs are suspect and the
diagnostic set is still incomplete, with some questions of consistency among
measurements and analyses still being resolved.