Alcator C-MOD Weekly Highlights November 18, 1993 The scheduled shutdown of Alcator C-MOD between Phase I and Phase II operating campaigns is continuing. Major upgrades planned for this period include installation of the flywheel to increase the stored energy available from the alternator, and replacement of the moveable monopole ICRF antenna with two dipole antennas. Additional scheduled activities include inspection of internal and external hardware, some diagnostic upgrades, and general maintenance. The 75 tonne flywheel has now been lifted by crane into the alternator house and placed in position. The bearings have been aligned to a tolerance of less than .002 inches. Work is proceeding on alignment to the alternator. Warmup of the vessel and structure has been completed, and the vessel is up-to-air.The monopole ICRF antenna and moveable outboard limiter have now been removed. Only minor damage, attributable to runaway discharges, was found on the outboard limiter, and the antenna was in good condition. On Wednesday, we had the first manned access to the vessel since last March. The first in-vessel activity consisted of a detailed inspection of all internals, including documentation on videotape and with still photography. Out of over 7000 molybdenum tiles, a total of 24 were found to be fractured (more than one third of the tile broken away), with less severe chipping or peeling damage to a similar number, making the failure rate well under 1%. Most of the fractured tiles were located on the lower EF1 conical shelf, a location which is not subjected to significant heat loads during normal operation. Analysis of the failure mode of these tiles is underway. The outer divertor modules, which experience the highest heat fluxes during divertor operation, are generally in good condition. In-vessel diagnostics were generally found to be in good condition. The upper tiers of igloo blocks and the top of the cryostat have been removed, allowing inspection of the external structure (dome and cylinder) and electrical busswork and connections. C.H. Ma, from ORNL, was onsite this week to continue installation work for his Faraday rotation experiment. This diagnostic, which is being incorporated into the existing two-color interferometer (TCI), will be used to measure poloidal field profiles during the next operating campaign. The Data Acquisition and Computation Group has taken delivery of new magnetic disk hardware, increasing our online storage capability by approximately 17 Gbytes. The new disks are now in sevice and will be used primarily for datafiles. The MIST impurity transport code is now running with a suitable C-MOD geometry. Modelling of laser ablation Scandium injections is being performed. Comparisons with brightness profiles measured with HIREX and soft xray arrays are being made.