Alcator C-MOD  
			Weekly Highlight Report 
			July 29, 1993

As reported last week, Alcator C-MOD is now operating with the EF3 coils in
series, and the OH1 interrupter circuit in the low voltage (2kV max), high
current configuration; this arrangement corresponds to the design
configuration for normal operation. Operation in this configuration is not
yet as reliable as had been achieved at the end of the previous campaign;
it is not clear whether this is due to poorer wall/vacuum conditions (we
have been operating just over a week) or because the fields have not yet
been optimized. Nevertheless, we have made significant progress acquiring
physics data.  All of this week's runs are dedicated to physics topics, as
opposed to discharge development. Typical operating parameters are:
toroidal field 5 Tesla, plasma currents of 450kA, density between 1.e20 and
2.e20/m3, limited discharges with elongations of 1.2 to 1.4. 

A systematic study of gas puff fueling was begun, using the A-side
piezoelectric valve which was installed during the last vacuum opening.
This valve has a faster conductance time to the vessel (about 15msec) than
the B-side or B-vertical valves. The purpose of this study was to
investigate fueling efficiency and to prepare for modulated gas puffing
experiments for perturbative transport studies. 

The fast scanning probe has been used to study the scrape-off layer
characteristics in a series of limiter discharges. This is the first time
the C-MOD scanning probe has been inserted into a tokamak discharge. 

Today's run is dedicated to obtaining electron and ion temperature profiles
for a range of densities at fixed plasma current. The HIREX system is being
employed for both electron and ion temperature measurements. The ECE
is also operating and producing electron temperature profile data. These Ohmic 
transport studies are slated to continue tomorrow.

The Chopper/EFC coil is now in routine use in the vertical position control
feedback loop. This system seems to be working well, although the crucial
test will take place when we increase the elongation to values above 1.5,
which were not well controlled using only the thyristor supplies.

The RF group has completed the coax connection from the FMIT transmitter to
the tuners and from there to the antenna. The RF transmission line is now
complete and has been successfully pressurized. The remote controls for the
tuner system are operational, and the data acquisition instrumentation has
been calibrated.

Three members of the Alcator Group (Hutchinson, Granetz and Porkolab) are
attending the EPS meeting in Lisbon, for which we submitted a post-deadline
paper on startup issues and other recent C-MOD results.