Alcator C-Mod Weekly Highlights January 6, 2008 FY2008 weeks of research operations: Target: TBD Completed: 1.06 weeks Operations ---------- Plasma operations resumed last week, with two run days devoted to ICRF conditioning. A total of 44 plasma discharges were produced, with a startup reliability of 80%. The net ICRF power coupled to the plasma reached a maximum of 6MW last week, with D-, E-, and J-port antennas operated simultaneously. The hydrogen fraction during ICRF operation has now been reduced to the point at which boronization of the vessel is appropriate. The cryopump was successfully operated during both plasma runs last week. The first boronization of the FY08 Experimental Campaign is scheduled to take place on Monday. Plasma operations are planned to continue during the remainder of the week. ICRF Systems ------------- The J-port (4-strap) antenna was operated up to 3MW during plasma operations last week, with the power limited by the power supply current for the FMIT#4 transmitter, rather than by antenna or transmission line condition. Real time phase control for this antenna was successfully tested. The matching was found to vary between co- and counter-current drive and heating phasing, but the variation was relatively benign and did not result in excessive trips. Previously observed interference on the FMIT#4 screen supply due to operation of FMIT#3 was successfully eliminated. Some self-interference on this screen supply is still present, and this will be investigated this week. Preparation is underway to install a pre-matching stub in the E-port antenna matching network to reduce the maximum voltage in the fast ferrite tuners (FFT) to <30kV during H-modes. Lower Hybrid System -------------------- New circulators have been received from the vendor and acceptance testing has begun. The circulators will be physically inspected, photographed, and checked for gas and water leaks. The internal ferrite integrity and braze flanges will be visually inspected. S-parameters of the ports will be taken and compared with test data supplied by the vendor. After inspection the circulators will be power tested. Work continued on the upgrade to the Coupler Protection System (CPS) and on development work for new LH waveguide window assemblies and matching transformers. Welding work for the fourth lower hybrid cart is proceeding. New temperature and humidity sensors were installed to monitor the microwave cabling. The LH transmitters were successfully operated up to 1.5MW for 0.5 sec into the intermediate water loads, in preparation for the next plasma operation. The system was also operated into plasma during some ICRF conditioning shots last week. Arrangements have been made for MIT engineers to witness testing of the refurbished klystron S/N 117 at the vendor's facility in late January. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly