Alcator C-Mod Weekly Highlights May 29, 2012 FY2012 weeks of research operations Target: 18 weeks Completed: 5.8 weeks Plasma Shots: 1000 Operations ----------- Plasma operations continued at Alcator C-Mod last week. Two run days were scheduled and completed. A total of 45 plasma discharges were produced with a reliability of 69%. The runs were devoted to diagnostic calibration and continued machine conditioning. Plasma operations are planned to continue this week. Program Planning ---------------- A meeting of the Experimental Program Committee was held on Monday 5/21. We discussed schedule and priorities for the balance of the campaign. We have received guidance for incremental FY2012 funding to raise our total to 18 weeks of operation. Run-time allocations have been set for each topical group and group leaders will reset their priorities accordingly. At the same meeting seven experimental proposals were reviewed and approved. Operation Details ----------------- Tuesday morning's run was devoted to MP#296, "Confirmation of Thomson scattering density calibration using electron cyclotron emission cutoffs". This MP was successfully completed, achieving ECE density cutoffs by running low field (~4T) with a steady density ramp. The cutoff plasmas ran until a poloidal detachment/disruption event, typically around 1.5sec, ended the discharge. These plasmas typically had density ramps from nebar~1.5-3.0e20/m^3, and B_T from 3.9 to 4.2T; the field was varied slightly in these discharges to shift the positions of the cutoffs to more closely match them to TS points. Using these data, we obtained channel-by-channel single-laser calibration coefficients. The remainder of Tuesday's run and all of Wednesday were devoted to MP#355, "ICRF conditioning". The D- and E-port dipole antennas were conditioned up to 1.2MW each into Upper and Lower single null target plasmas. The H/(H+D) ratio started at 10% and rose to about 16% during RF operation. ICRF Systems ------------ Repair of the J3 stub tuner unit in the power room was completed. The external matching network on the J-port (field-aligned) antenna was reconfigured based on improved measurement of the S parameters. Lower Hybrid System ------------------- The LH system was operated in piggyback during Wednesday's ICRF conditioning run. The LH system operated reliably at high density (nebar ~ 2e20 /m^3) during ICRF. However, operation at lower densities (nebar 1-1.5e20 /m^3) resulted in increased faulting. Travel and Visitors -------------------- Seungil Park and Junhee Kim from KSTAR/NFRI concluded their two week visit to C-Mod on Thursday. Drs. Park and Kim were shown how to use the GENRAY/CQL3D simulation codes during their stay. They also observed C-Mod LHCD experiments and discussed operational details necessary for the installation of an LHCD launcher on KSTAR this fall. P. MacGibbon visited the MIT Bates Accelerator Center on Thursday to acquire documentation and a surplus power supply for the RFQ (radio frequency quadrupole) accelerator system. Brian LaBombard, Graham Wright, Odd Erik Garcia and Ralph Kube (Visiting C-Mod from Tromso, Norway), Bruce Lipschultz, Jim Terry, Dan Brunner, Roman Ochoukov, Regina Sullivan, Dennis Whyte, and Kevin Woller participated in the 20th International Conference on Plasma Surface Interactions 2012 in Aachen, Germany, May 21-25. Copies of their presentations are available at http://www.psfc.mit.edu/research/alcator/pubs/PSI/psi20/psi_index2012.htm _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly