Alcator C-Mod Weekly Highlights December 31, 2007 FY2008 weeks of research operations: Target: TBD Completed: 1.06 weeks Operations ---------- Last week was a maintenance week at Alcator C-Mod. No plasma operations were scheduled. With the exception of time devoted to vacuum conditioning of the ICRF antennas and testing of the diborane system, continuous electron cyclotron discharge cleaning (ECDC) of the tokamak was carried out in conjunction with a 60C bakeout. Plasma operations are planned to resume this week. Diagnostic Neutral Beam System ------------------------------ We were able to continue conditioning of the beam last week after our supplier, the MIT Cryogenics Lab, was able to supply a partial delivery of the liquid helium needed for the DNB cryopumps. The highest beam parameters obtained thus far following the installation of the new cathode assembly are 50 kV and 4.3 Amps for 0.5 sec. Further conditioning is planned for this week. ICRF Systems ------------- The final power amplifier (FPA) tube in FMIT#4 failed last week during vacuum conditioning of the J-Port antenna. A replacement tube was installed and tested into a dummy load at the 2 MW level; vacuum conditioning then continued. The J-Port antenna has now been conditioned to ~30 kV for ~100 ms. More conditioning is planned for this week, with the goal of 35 kV for 1 sec pulses. We also investigated installing some pre-matching passive components in the transmission line network for E-port antenna to reduce the maximum voltage in the Fast Ferrite Tuner (FFT) double stub matching network. We have a design that is projected to reduce the maximum voltage by ~40%. If successful, this change will allow the FFT's to provide full power to the E-port antenna during H-modes. Computer and Data Acquisition Systems -------------------------------------- A new server rack was installed in the control room to house the C-Mod data archive and infrastructure computers. Three new power circuits were added to support it. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly