Alcator C-Mod Weekly Highlights Jan 16, 2001 Work continued at Alcator C-Mod last week on modifications to the J-port ICRF antenna, repairs and refurbishment to the DNB diagnostics, and continued maintenance of engineering systems. General Engineering ------------------- The LN2 sump was opened up last week and the LN2 pump filters were removed and cleaned. The filter for the TF first-to-last turn leg was also inspected and found free of any debris. Some components for the inner divertor upgrade are arriving from our vendors. Inconel 718 bolts needed for the upgrade are now in house as are some of the molybdenum tiles. A small quantity of tiles from one vendor did not meet spec and have already been returned to the vendor to be reworked. Major components such as backing plates and C-plates that make up the girdle are on schedule. Modifications are nearly complete of the OH commutation bank that will allow for much easier inspection and component replacement. A failed capacitor in one of these banks took several days to find and replace during the last run period. ICRF Systems ------------ The fabrication of the new boron nitride tiles for the J-port antenna was completed last week. The tiles were cleaned and then baked at 500C over the weekend to prepare them for invessel installation. Fit up of the new antenna septum indicated that modifications to the stainless steel spline that holds the BN tiles would be required. These changes will be completed this week. Mockups of the new dB/dt probes were also fit up on the antenna, and exact lengths for the coax signal leads were determined. We have decided to delay the pumpdown somewhat so that a better inspection and cleanup of, and possible modification to the antenna feedlines could be undertaken. Tracking and arcing marks discovered between the strip lines and septum need careful evaluation. These components have not been inspected since the beginning of the 2000 run campaign (Jan 00). DNB and Related Diagnostics --------------------------- The DNB optical diagnostics have been carefully inspected. The CXRS optics were still in alignment, but had been coated during vessel boronizations. They were removed from the vessel and cleaned. Hoods will be added to slow the boron deposition rate. The MSE/BES optical alignment was found to be shifted by approximately 1 cm since the last calibration due to disruption damage to one of the mirrors. That mirror and its support were removed from the vessel for repair. An inspection of the inner wall of the vacuum vessel opposite the DNB duct showed no beam damage. Also, there was no further beam-induced damage to the DNB duct. Baking of the beam line has begun in preparation for offline operation of the beam which will continue during the up-to-air period. Visitors and Travel ------------------- Gary Taylor spent the week at C-Mod working on the electron cyclotron emission diagnostics. A PPPL microwave source was used to optimize GPC2 signals and to carry out tests of the instrument functions of both GPC and GPC2. Steve Wolfe and Ron Parker participated in the DIII-D Advisory Committee Meeting at General Atomics in San Diego last week. Wolfe also presented a talk on recent C-Mod results to the DIII-D group.