Alcator C-Mod Weekly Highlights April 25, 2003 Plasma operation continued Tuesday through Friday this week. Commissioning of the LH klystrons made excellent progress, and the Lower Hybrid MIE Project can be declared complete. Plasma conditioning of the ICRF antennas has begun. Operations ---------- Machine operations this week concentrated on plasma cleanup. Low density plasmas were produced throughout the week as we cleaned the plasma facing surfaces and began reducing the amount of hydrogen in the discharges. Startup reliability, which began at 50% on Monday, was 86% by Thursday. Cleanup and rf conditioning of the rf antennas will continue next week. Physics ------- On Friday, the first run with the new non-axisymmetric control coils in operation took place. Early in the run, low density discharges showed evidence of locked mode activity. However, changes in the density later in the run made it difficult to assess the effect of the coils. These experiments will continue when the machine is better conditioned, and probably with higher plasma currents where more robust locked modes can be produced. Lower Hybrid Project -------------------- Eleven of the twelve klystrons are now operational at power levels of more than 200 kW and pulse lengths of 1 s. Nevelle Greenough, PPPL, spent the week at MIT to help with the commissioning effort. Work has also continued on phase and amplitude control electronics. Fabrication has begun on PLC electronics required to control the launcher temperature regulation system, and positioning equipment. The design of fixturing required to mount the launcher in our vacuum test stand is proceeding. A new clean room for working on the launcher vacuum components is being constructed in the rf lab. ICRF Systems ------------ Plasma conditioning of the ICRF antennas was started this week. Both D and E-Port were conditioned to ~ 1 MW and ~20 kV. J-Port reached 250 kW, but a fault in a low power relay and rf preamp stopped conditioning efforts until repairs can be made. Diagnostic Neutral Beam ----------------------- The beam is again in operation during C-Mod discharges with good beam performance. All beam control software has been ported to Linux. Travel and Visits ----------------- Manfred Bitter and Ken Hill, both from PPPL, were at MIT on 4/22-23/2003 to discuss the installation of the NSTX X-ray imaging crystal spectrometer on C-Mod with John Rice and Earl Marmar. The spectrometer consists of a spherically bent crystal and a 10 cm x 30 cm large position-sensitive detector and will provide radial profiles of the ion and electron temperatures, the toroidal plasma rotation velocity, and the ionization equilibrium. Stewart Zweben, PPPL, was at C-Mod 4/22-25 and helped prepare the Gas Puff Imaging diagnostic for the run. Initial data was taken using the two Xybion cameras, and nice images of the edge turbulence structure were obtained. Steve Wolfe traveled to San Diego to participate in the review of the General Atomics proposal for operation of DIII-D for the next five years.