Alcator C-Mod Weekly Highlights Feb 28, 2005 FY 2005 weeks of research operation planned: 17 weeks, completed: 0.4 weeks. Last week was a maintenance week at Alcator C-Mod. No run days were scheduled. Plasma operations are planned to resume this week. Operations ----------- No plasma runs were carried out during the maintenance week. A series of gas-puff only shots were performed on Friday to test archiving of data from the RGA and various pressure gauges and valve status indicators. Physics ------- The C-Mod Experimental Program Committee met on Friday to consider Miniproposals for experimental time during this campaign. Ten MP's were approved. The current list of C-Mod Miniproposals can be viewed at http://www-cmod.psfc.mit.edu/cmod/cmod_runs.php?miniproposals=1 ICRF Systems ------------- With the help of Chris Brunkhorst (PPPL), all of the ICRF transmitters were tested last week. The primary goal was to investigate 50 MHz transmitter operation. FMIT#3 and FMIT#4 (J-port four-strap antenna) were tuned to 50 MHz, the operating frequency for He3 minority heating experments at 5.4T. Each transmitter operated successfully into vacuum, but simultaneous operation of both transmitters was limited by a parasitic oscillation. We plan to operate into plasma this week to further investigate this effect, and to see if the oscillation is suppressed when the Q of the system is lowered in the presence of plasma. A fault in the FMIT#1 (D-port dipole antenna) coaxial switch prevented high power operation into plasma with this antenna during the week before last. We are working to bring this system back online this week. Improved tuning of the FMIT#2 transmitter has reduced the FPA screen current, which will allow the transmitter to operate more reliably up to the 2 MW level. Lower Hybrid System ------------------- Calibrations of the signal cabling required for control and monitoring of amplitude and phase of the Lower Hybrid launcher power is underway. Timing signals between the Actove Control System (ACS) and the transmitter were tested successfully. Calibrations of the CPS (coupler protection system) were completed. Diagnostics ----------- A new computer for the FRCECE diagnostic was assembled and tested at UT-FRC and shipped to MIT for installation next week. During the last week of plasma conditioning, the processor in the previous computer failed due to a failure of a cooling fan. The CXRS spectrometer was refocused and recalibrated for the physics phase of the C-Mod run campaign. The TCI (two-color interferometer) CO2 laser developed an alignment problem resulting in low power and poor beam quality; the laser was repaired by the vendor (at no charge). DNB System ---------- The new long-pulse diagnostic neutral beam has arrived on-site, and a team of engineers from the Budker Institute of Nuclear Physics (Novisibirsk) is working with C-Mod personnel to install the beam in the C-Mod cell. Travel and Visitors ------------------- Randy Wilson and Nevell Greenough (PPPL) spent the week at C-Mod working on the Lower Hybrid System. Chris Brunkhorst (PPPL) was also at C-Mod, working on retuning the transmitters supplying RF power to the 4-strap ICRF antenna to 50 MHz. Ivo Furno (LANL) was at C-Mod last week, working on installation of the infrared camera used for power deposition measurements in the C-Mod divertor. Prof. Ambrogio Fasoli of the CRPP-Lausanne is visiting the PSFC from 22 - 28 February as part of the MIT/CRPP/JET collaboration to discuss energetic particle physics studies on C-Mod and JET. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly