Alcator C-Mod Weekly Highlights March 19, 2007 FY2007 weeks of research operations: tentative target: 15 weeks Completed: 0 weeks Operations ----------- Operations resumed last week on Alcator C-Mod with Power System testing in preparation for plasma operations. Five run days were scheduled but only two and a half days of testing were completed. Time was lost to repair of an Uninterruptable Power Supply (UPS) in the power room, and to trouble-shooting the Access Control software. Several bugs in the new operator interface software to the programmable logic controllers (PLCs), including Access Control, Power Systems, and the State Display, were identified and are being addressed. By Friday, all of the power systems had been successfully tested, and the first plasma shot of the campaign was attempted, resulting in an initial breakdown plasma. Initial testing of the drive systems for the inner-wall "WASP" scanning probes (MP#465) was successfully carried out during the TF test sequence on Thursday. Monitoring of magnetics signals during power tests revealed intermittent connections at one vacuum feedthrough, affecting at least five flux loop signals. Possible remedies are being investigated. Electron cyclotron discharge cleaning (ECDC) and a 60C bake are being carried out over the weekend. C-Mod Start-up and Conditioning operations are planned to continue this week. Lower Hybrid System ------------------- All twelve klystrons have now been calibrated at full power. Additional calibrations under different ambient temperature conditions are planned. A noise source responsible for spurious triggering of the HV crowbar circuit has been identified and repaired. A meeting of personnel involved in the design of the new Lower Hybrid launcher system was held on Wednesday. A proposed baseline design, incorporating an E-plane launcher design with four 16-window couplers (total 64 waveguides) to be fed by 8 klystrons, was discussed. Long Pulse Diagnostic Neutral Beam ---------------------------------- A seal on the DNB cryo-pump, which had been the cause of a vacuum leak, has been repaired and successfully leak-checked. Beam operation has resumed with nearly 100 conditioning shots to date. The beam spectra show significant reductions in water content. Beam voltage has been in the 48kV range, with initial beam currents typically around 6A. Conditioning is proceeding to improve the beam current flatness over the 1 second pulses and to approach full parameter operation (50kV, 7A, 1.5 second pulse). ICRF Systems ------------- we are following our normal proceedure for bringing the ICRF system on-line for the upcoming campaign. Three out of the 4 transmitter's high voltage systems have completed their testing and FMIT#1's high voltage testing is planned for this week. We plan to begin power testing the FMIT#1 and #2 into the dummy load this week and also plan to complete the coax configuration for the D antenna. The E antenna coax configuration awaits the construction of the stands to support the Fast Ferrite Tuners. The in-cell phase shifter in the D-port antenna transmission line was successfully repaired, following observation of arcing in this unit. Teflon was removed from the phase shifter and stub tuner as has been previously done for the E antenna phase shifter and stub tuner. Cryopump System ---------------- Work is proceeding on the external LHe and LN2 lines, as well as the PLC control system. Diagnostics ----------- Diagnostics continue to be brought on-line in preparation for initial plasma operation. The Balmer alpha diagnostics and CIII visible light monitor have been brought on-line. The electron cyclotron emission (ECE) Michelson system is operational. The neutron detector system is in place and on-line. The hard X-ray monitor is on-line, although a small pickup signal observed during power system tests is being investigated. Eight in-situ Penning ionization gauges, including two new gauges in the upper cryopump gas box, are operational. The real-time neutral pressure monitor (ratiomatic gauge) is on-line but not yet calibrated. Two of the plasma TV views, one wide angle view and a view of the divertor and one ICRF antenna, are on-line. Additional views will be added this week. Langmuir probe arrays at the lower inner- and outer-divertors, on the lower hybrid launcher, and the new probe array at the upper divertor, are operational. Density, electron temperature, and particle flux are reported every 10 msec. In addition, two high-gain channels for ECDC plasma diagnosis have been installed in the upper divertor array. The F-port scanning probe is operational with the perpendicular Mach probe installed. Travel and Visitors ------------------- David Gates of PPPL visited Friday, March 9 and gave a seminar on NSTX. While here, he met with Catherine Fiore, Bob Granetz, Joe Snipes, Martin Greenwald, Amanda Hubbard, and Steve Wolfe. Chun Kung (PPPL) visited the PSFC last week to install a swept-frequency reflectometer for measurements of the radial correlation length of density fluctuations. Earl Marmar, Amanda Hubbard, and Miklos Porkolab were in Washington last week. On Monday Earl participated in a meeting of the Fusion Facilities Coordinating Committee at DoE. On Tuesday and Wednesday all three attended the OFES Budget Planning Meeting, where Earl and Miklos gave presentations. The C-Mod presentation is linked at http://www.psfc.mit.edu/research/alcator/program/C-Mod_BPM_Presentation_2007.pdf On Monday, March 12, Miklos Porkolab and several other fusion laboratory directors visited key congressional energy subcommittee appropriation and authorization staff and explained the status of domestic fusion research, ITER, and the presidential budget request for the next two years. In general, they found very positive bi-partisan support for fusion research as a means to secure CO2 free energy for the future. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly