Alcator C-Mod Weekly Highlights January 11, 2002 Reassembly of Alcator C-Mod has begun. In addition, work continued on the ICRF systems, Lower Hybrid MIE project, and Inner Divertor Upgrade. Physics ------- We continued our remote collaboration with ASDEX Upgrade on matching pedestal conditions. Dedicated C-Mod experiments were run in July 2001. AUG has resumed operation after a maintenance period. On Friday, Jan 11, they began the first part of their comparison experiments, focussed mainly on shape development. They obtained a good match to the dedicated C-Mod shots and also, unexpectedly, were able to closely match the shape of our more typical EDA discharges. Both NBI and RF heating were used. Further experiments aimed at matching dimensionless plasma parameters and comparing ELM behaviour will continue later in their winter campaign. Operations ---------- With the installation of the OH2L coax early this week, reassembly of Alcator C-Mod was begun. Torque checks will be complete on the coax early next week at which point the installation of cover plates, the lower wedge plate, and lower TF arms can be staged. Hi-Pot and ringing tests of all the EF magnets were successfully completed this week, as were similar tests on the OH2L magnet. The OH1 and OH2U magnets will be tested as soon as installation of their respective coaxes is complete. Hi-Pot turn-to-turn tests of the TF core were also completed successfully. We continue work on the TF and Thermocouple scanner upgrades. A controller PC has been selected for purchase. Communication links are being defined and tested for speed. Work on the drive amplifier for the MHD antennas continued this week. The prototype amplifier is now operating over a DC to 1 MHz band at the 10 Amp, 60 Volt level. We expect to push up these parameters somewhat next week. Lower Hybrid MIE Project ------------------------ Three of the four klystrons on CART3 have been installed in the cell. A picture of the klystrons and cart can be found at http://www.psfc.mit.edu/cmod/operations/EngImages/RF/lower_hybrid/DCP_0117.JPG Final testing has begun on cart2 in preparation for its move to the cell. Wiring of the HV Junction Box that interfaces the transmission line from the HVPS to the cell has been completed. Two engineers from the vendor that supplied the HVPS are on-site and preparing for the supply acceptance tests. At PPPL, procurements have now been placed for many of the LHCD components (items within vacuum boundary): couplers, flanges, shroud, interface flange, and ceramic windows. The remaining "Phase 1 Components" have been sent to vendors for RFQ, and awards are expected shortly. These include the forward wave guides, and those parts required for the completion of "front end & vacuum components." Procurement of further components is presently limited by available funding. ICRF Systems ------------ Machining of the D&E Faraday screens has begun in our shop. Modifications are being made so that the metal to boron nitride interface can be shielded from interaction with the edge plasma. During the last campaign these regions sometimes limited plasma performance with impurity injections. In addition, the D and E-port current straps sustained some arc damage and required some reconditioning. We have deburred the straps and are preparing them for brush plating. Also during the last campaign, we found the power handling capability of the J-Port antenna was limited by development of a discharge where the current strap passed under a grounding bridge that terminated the end of the strap. Detailed analysis of this region indicates that changes to its width and contouring will increase the power handling capability by more than 50%. We are proceeding with the modifications required. The first demodulator PC board has been populated and testing has begun. The PLL synthesized LO section of the board is working extremely well. Initial tests of the phase detector also indicate proper operation. DNB and Related Diagnostics --------------------------- The DNB layout for the cell was forwarded to Budker Institute with addition of cable tray details to allow interconnect cables to be fabricated. The fueling system design was completed and made available for fabrication. PLC software is now in progress along with associated PLC and vacuum rack modifications. Initial tests of the C-Mod shot synchronization software were successful. The output signals for the beam will be verified next week and results made available for comment. Fabrication of the beam and pulse transformer supports has not yet begun. Matt Sampsell, UTexas, visited MIT to begin preparing the beam diagnostics area so that diagnostic assembly can begin for the next campaign. During the last week and a half a lot of work has been done on the MSE/BES canister. Two machinists at PPPL are working in parallel on this project. The modifications to L2, L3, M2 and M3 designed by Paul LaMarche, PPPL, are nearly complete. Final ray trace evaluations are being supplied by Ron Bravenec at the University of Texas after which cutting of the M2 mirror can begin. Other modifications are proceeding as well. A new more rugged mount for the M1 mirror is nearly complete and will be sent to MIT to be blackened and then sent back to PPPL for final assembly. The canister split, and addition of new flanges to allow this vertical section to be rotated and removed, will begin January 14. Work has also begun on modifying the external polarizer sheet holder; it will now be removable rather than fixed. We expect to begin assembly of the canister by late January. Inner Divertor -------------- All studs and high strength bolts have been torqued to specification. Tiles installation will resume next week. We continue installation of new diagnostic cable runs. The new probe arrays for the inner divertor are on schedule for installation late this month. Travel and Visits ----------------- Matt Sampsell visited from UTexas to work on the DNB diagnostic installation.