Alcator C-Mod Weekly Highlights
			October 6, 1997

The maintenance period on Alctor C-Mod continued last week. No runs were
scheduled.

The Alcator C-Mod vacuum vessel underwent a three day bake at 100C in
preparation for operation.  The vessel is now back at 35C, and Electron
Cyclotron Discharge Cleaning (ECDC) is continuing. 

All blocking, insulation, and wedges were installed on the alternator rotor
and a hi-pot to 6000 volts was completed successfully. The retaining rings
were then installed and the final acceptance hi-pot (5000V) was completed 
over
the weekend. The rewind of the alternator rotor is now complete. The tooling
and machinery used in the rewind operation are being removed from the site.
The re-assembly of the alternator will begin this week.

Work on alternator instrumentation and auxiliary systems also continued last
week. The varistor shunt signal has been wired to CAMAC through an isolation
amplifier. Wiring to CAMAC to add a signal from a current transformer on the
stator ground is done. The rotor V and I are wired into CAMAC. A four-channel
isolation amplifier board was built and installed. 

In the RF area, the tuned arc detectors have been completed and are awaiting
testing and calibration.  Testing of FMIT#1 and #2 power feed back circuits
has begun.

Professor Yuichi Takase is visiting from the Tokyo University until late
November.  He will be heavily involved in commissioning D and E port antennas
this upcoming campaign.  He will also be involved in data analysis and
discussions of future RF experiments.

Data obtained during ECDC experiments carried out in September has been
analyzed; characterization of the ECDC plasmas is of interest to ITER.  We
used the Omegatron diagnostic to make electron density, electron temperature,
and ion temperature measurements of electron cyclotron discharge cleaning
(ECDC) plasmas.  By varying the strength of the toroidal field, we scanned 
the
radial location of the cyclotron resonance, and effectively moved the plasma
relative to the measurement point (the Omegatron).  At each resonant location
we recorded electron temperature and density with Langmuir probes on the
Omegatron diagnostic.  With deuterium fill pressure of approx. 3e-4 Torr, we
recorded electron densities of approx. 1e16 m^-3, dropping sharply as the
resonance location moves outside the measurement location.  We recorded
corresponding electron temperatures of approx 10 eV; for ECDC plasmas, the
electron pressure profile looks approximately constant at .020 Pa, dropping
sharply as the resonant location moves outside the measurement location.  We
measured ion temperatures with the retarding field energy analyzer (RFEA)
component of the Omegatron diagnostic.  We observed ion temperatures of 2 eV,
approximately constant across the ECDC plasma, decreasing as the resonance
location moves outside the Omegatron.

Two additional SCSI busses were installed on the main data acquisition server
bringing the total up to 5.  This will allow each of the four CAMAC highways 
to be attached to its own bus.  This was done to improve the reliability of 
the 
CAMAC highways by reducing their interdependancy.

Installation of the high voltage, low capacitance transmission line for the
DNB began with construction of supports for the principal transition box
and test installation of the box itself.  Relocation of the process gas
system for the DNB plasma source was completed.  Design of the suppressor
switch control interface was completed and construction began.  This unit
will support communication with the DNB PLC and control by the fast logic.

Dave Johnson and Ben LeBlanc from PPPL were onsite last week, working on the
x-point Thomson scattering system.