Alcator C-Mod Weekly Highlights August 27, 2001 The Maintenance, Upgrade and Inspection period continued at Alcator C-Mod last week. Partial disassembly of the machine is proceeding, and preparation for the planned upgrade installations is progressing on schedule. Operations ---------- The cryostat has been disassembled and moved away from the machine. The machine connections, cooling tubes, and electrical insulation are in very good condition. The status of these systems has been documented, and we are continuing with disassembly. A view of the machine can be found at http://www.psfc.mit.edu/cmod/operations/EngImages/Inspection_2001-2002/Disassembl y_Assembly/P0001863.JPG The k-port horizontal flange is being prepared for removal in this picture. The in-vessel railing to support divertor modification activities has been installed, and inner divertor work is proceeding. The LED in-vessel lighting system has been installed and is operational. Additional LED spot lights have been purchased and installed. New tent racks to facilitate vessel access are in place. The Power Systems Group has completed plans for the installation of cooling fans in the TMX supplies, including both the mechanical and electrical aspects of the job. The parts and tooling for the job have been ordered. The construction of the prototype duct box for cooling of the Interphase transformers at the TF supplies is in progress. The cell is now ready for outside contractors to begin their work on the new mezzanine needed to support the lower hybrid klystons. Transformers located on the east wall of the cell have been relocated on the north side, freeing up space for the mezzanine. RF transmission lines have also been moved out of the way, and diagnostic systems have been removed from the cell. ICRF Systems ------------ All three ICRF antennas and their associated vacuum feed thrus have been removed from the machine. This includes the Faraday screens from D and E-port antennas that have not been removed in over 5 years. To summarize the observations from the inspection thus far, the feedthrus for J and D-port antennas are in excellent condition. Two of E-port's feedthrus will require some work to repair arc damage on the vacuum side. There is evidence of arcing between the D and E-port antenna straps and their respective Faraday screen. The BN tile fasteners show some damage from excessive heat. The J-port Faraday screen is in good condition, and the straps have arc damage at the ground bridge. As on D and E, the J-port BN fasteners show damage associated with overheating. Diagnostic Neutral Beam Systems -------------------------------- The DNB duct was completely detached from C-Mod to make way for continued disassembly of C-Mod. The duct was removed, inspected and stored. The in-vessel MSE optics were detached from the F-port flange to allow removal of the flange. These optics were also detached from the in-vessel supports in preparation for removal from the vacuum vessel along with F-port early next week. Lower Hybrid MIE Project ------------------------ The concrete pad to support the HVPS has been poured. Several meetings between contractors, and MIT and C-Mod personnel were held throughout the week to make sure the pad will conform to spec. One of the new CPCI data acquisition crates has been installed in the Lower Hybrid control room for use during power supply and active controller testing and eventually for data acquisition in that area. Inner Divertor -------------- The vendor continues to make good progress on the remaining girdle plates. We continue to make fitups and test new diagnostics that will be installed in and behind the divertor. Removal of the old inner divertor modules is 95% complete. The survey of the inner wall has been completed. Preliminary installation trials with the stud welding fixture are complete. Visitors and Travel ------------------- David Mikkelsen (PPPL) visited MIT and ran EFIT, with help from Steve Wolfe. He has now demonstrated that the 'q' and magnetic shear at the mid-radius of C-Mod plasmas are not strongly constrained by the available data (including the sawtooth inversion radius at a/3). He also discussed with Earl Marmar the prospects for improving the constraints on q and shear, using the Lithium pellet ablation cloud internal magnetic field measurements, which could make possible more definitive predictions of turbulent transport. Rex Gandy from University of Idaho visited PSFC from Monday, August 20 to Tuesday, August 21. He and Yongkyoon In discussed the electron temperature fluctuations using radiometry.