Alcator C-Mod Weekly Highlights February 22, 2002 Alcator C-Mod was moved from the assembly area to the center of the Cell this week. Work also continues on the new DNB installation, ICRF systems, and the Lower Hybrid MIE Project. Physics ------- At the Physics meeting, Catherine Fiore presented preliminary calculations of the electrostatic potential and radial electric fields in CMOD ITB shots, generated by the input of central toroidal rotation measurements into TRANSP. The highest value of the resulting EXB shearing rate peaked at 8e4/s in the ITB region after the ITB was fully developed. Further work is needed to compare this result with the ITG growth rates. Joe Snipes presented a preview of the talk he will give at the ITPA Confinement and Threshold Database meeting in Princeton 11 - 14 March on the Latest H-mode Threshold Results and Future Plans. The talk covered the inner gap scan experiments that were presented by C. S. Pitcher at the APS meeting in Long Beach. There does not appear to be an increase in threshold down to a 3 mm inner gap within the measurement errors. Closing the gap still further to produce inner wall limited plasmas, however, increased the threshold dramatically to the point where 2.7 MW of launched ICRF power was insufficient to get into H-mode. More experiments on this topic are planned during the next run campaign when more ICRF power will be available. Operations and Power Systems ---------------------------- All lower TF springplates were installed and carefully documented for proper operation this week. TF joint resistances were measured and turn-to-turn hi-pots were conducted. All measurements indicated successful completion of the lower TF arm installation, and the machine was moved from the assembly stand to the lower dome at the center of the Cell on Friday. A picture of the "big lift" can be found at http://www.psfc.mit.edu/cmod/operations/EngImages/Inspection_2001-2002/Disassembly_Assembly/Machine_assembly_A/DCP_0196.JPG We continued maintenance work on the alternator this week in preparation for the next run campaign. Cooling water pumps are being refurbished as is the varistor bank that protects the rotor from over-voltage. Lower Hybrid MIE Project ------------------------ We have stopped the commissioning activity on the HVPS until several issues with the control system can be addressed by the vendor. We expect to resume the commissioning process late March to early April. Though the supply has reached current, voltage, and pulse length specifications, the control system as it currently programmed will not allow safe operation of the supply with our klystrons. We continued installing the cabling between the klystron carts and the various control and protection cabinets this week. Waveguide is being prepared for installation on the klystrons. ICRF Systems ------------ Chris Brunkhorst (PPPL) visited this week to participate in commissioning of FMIT#3 and #4 in preparation for the upcoming campaign. Transmitter and screen crowbars were tested. FMIT#3 was successfully tested to 1.8 MW into a dummy load. FMIT#4 was limited by a low power problem that will be addressed next week. DNB and Related Diagnostics --------------------------- The first contingent of Russian engineers from the Budker Institute arrived this week to begin assembling the diagnostic neutral beam, which has been loaned to us by Consortium RFX in Italy. Over the next four weeks, a total of eleven Russian scientists and engineers will assemble, install, and commission the DNB. Completion is scheduled for 24 March, in time for the beginning of tokamak conditioning operations. The new spectrometer for the CXRS is being ordered this week. A design review for the new high-resolution edge CXRS in-vessel optical system was held this week. No significant problems were found, and final drawings for construction will be ready next week. Russel Feder, PPPL, continued to work on the new ferrules and ferrule holder for the MSE/BES Image Dissector with Ron Bravenec, U. of Texas, and Howard Yuh, MIT. The ferrules for MSE have been merged into larger rectangular ferrules, and the new design should be generally easier to work with. Other Diagnostics ----------------- Work at PPPL continued on the 130/140 GHz TFTR reflectometer upgrade for C-Mod. Power supplies have been built and tested. During microwave circuitry checkout two of the Gunn oscillators were found not to be in proper working condition, and have been returned to the manufacturer for further testing. Travel and Visits ----------------- Martha Redi, PPPL, was here this week, doing further exploration of the stability of dual frequency heated ITBs on CMOD. David Mikkelsen gathered information relevant to transport simulations at MIT February 18-22, and began to use the MIT Beowulf cluster. He also spoke with Joe Snipes about the possibility of using PPPL codes to analyze Alcator C-Mod plasmas with locked modes. Miklos Porkolab gave a talk at the AAAS meeting in Boston last Sunday, Feb. 17, as part of a panel discussion on the future of Nuclear Energy entitled "Recent Progress in Fusion Research and Future Prospects." The lecture was well attended and covered by the news media.