Alcator C-Mod Weekly Highlights Nov 6, 2000 Plasma operations resumed on Alcator C-Mod last week. Three run days were scheduled and completed. The runs were carried out with reversed toroidal field and current, and were the first runs following an up-to-air. Startup reliability was relatively low, and only 19 plasma shots were obtained, with a reliability of 33%. Aside from machine conditioning, the principal experiments were concerned with fluctuations and transport in the SOL. From Friday afternoon until Saturday morning of last week Alcator C-Mod was boronized. An average layer thickness of about 1800 Angstroms was deposited. Approximately 48 hours of electron cyclotron discharge cleaning was then performed in deuterium gas. The new long pulse TF instrumentation was made operational last week during normal plasma operation. The new CAMAC equipment is operational and wiring from the CAMAC to the magnet supplies is complete. The connections to the remaining magnet supply buses and transformers will be made over the next two weeks as we prepare for the long pulse engineering tests scheduled for the end of the month. Plasma operations with reversed field are scheduled to continue this week. ICRF System ------------ The J-port antenna transmission line has been reconfigured for 2-srap, dipole operation and vacuum conditioned to 25 kV in preparation for plasma operation. Additionally, we tested a Ni plated FPA flow meter in FMIT#4. After two weeks of operation, the water quality in #4 degraded below 2 Mohm-cm (actively monitored). Upon disassembly, the Ni plating was found to have been replaced with oxidized iron (from the material originally coated by the Ni). We changed the flow meter to a teflon coated one and the water quality immediately improved to >2 Mohm-cm. Lower Hybrid System ------------------ This past week, Montgomery Grimes, George MacKay, and Frank Shefton travelled to PPPL to disassemble some of the last transmitter modulator equipment on loan to PPPL. Valuable items, such as high-voltage relays, and high-power tetrode tubes were removed for possible use in the Lower Hybrid transmitter. The smaller items removed were driven back to MIT, while the larger items were identified for shipment by PPPL. On a related subject, more of the loaned equipment (control racks and supplies) shipped by PPPL was received at MIT. DNB Systems ----------- Interlocks were added to prevent the DNB from firing after fizzles and disruptions and when the diverting magnet is not operating. Pressure gauges were added to the beam line. Travel and Visitors ------------------- Steve Wukitch attended the US/Japan technology exchange at PPPL. At the exchange, a fast ferrite tuner prototype was discussed; a performance test of this device will be made on C-Mod in the near future. Boyd Blackwell from the Australian National University visited Josh Stillerman and Tom Fredian to discuss the electronic logbook database applications developed here and their possible use on the H-1 experiment at ANU. Perry Phillips visited to work on the ECE radiometer. The high resolution ECE radiometer is back in operation. The repaired RF units have been reinstalled. Protection has been added to the power supply to prevent damage to the LOs. All 32 channels are now working. We are in the process of setting the gains and offsets to optimize the signals. Tomohide Nakano visited last week as part of the collaboration with JT-60U. He primarily spent time with Jim Terry and Bruce Lipschultz discussing spectrosopy of impurities in C-Mod and JT-60U. The main topics covered were CX population of excited states of C and B, whether emission lines for such processes existed in C-Mod, the role of the main chamber in impurity sources and core impurity levels, the spectroscopy of highly ionized impurities (w/J. Rice) and wall recycling in general. It was a very fruitful visit. On the one hand he stimulated our thinking regarding possible diagnosis of B ion using CX methods. On the other he benefited from a discussion of impurities and the core that incorparated the wall sources, which are ignored in JT-60U.