Alcator C-Mod Weekly Highlights October 6, 2008 FY2009 weeks of research operations: Target: TBD Completed: 0 weeks Physics ------- Information about the main ion velocity in the pedestal region can be inferred by comparing estimates of the main ion diamagnetic contribution to the total radial electric field profile. This comparison is potentially useful as it lends itself to determining source information about the radial electric field and can be used to compare to theoretical predictions of main ion behavior. An estimate of the main ion diamagnetic contribution (using TS electron profiles) demonstrates a radial electric field profile with remarkable similarity to the total radial electric field profile, but radially shifted (~4mm) and displaced in magnitude. A detailed comparison of the TS electron temperature profiles and the CXRS boron temperature profiles indicate that the EFIT mapping of the TS profiles is likely incorrect by at least 3 mm. This mapping error eliminates, within the error bars, the radial shift between the total electric field profile and the main ion estimate, but does not account for the magnitude displacement. To bring the main ion estimate into agreement with the calculated Er profile, the main ions must have either significant co-current toroidal rotation or ion diamagnetic poloidal rotation, or some combination of the two. The exact magnitude and shape of the main ion toroidal and poloidal velocity profiles can not be determined within the error bars, but the results are not in disagreement with neo-classical predictions of main ion velocities in the Pfirsch Schluter regime, and it is clear that the main ions can not be stationary in the edge. TOFE Meeting ------------ Several of our engineers attended the 18th Topical Meeting on the Technology of Fusion Energy in San Francisco, CA from September 28 to October 2, and presented posters on engineering systems developed or being developed for C-Mod: Engineering Considerations in the Implementation of High Power Fast Ferrite Tuners on Alcator C-Mod, Alan S. Binus Disruption Load Calculations for Lower Hybrid Current Drive Couplers, Jeffrey Doody Transmitter Protection System Upgrade Design for Lower Hybrid Current Drive System on Alcator C-Mod, David R. Terry (presented by Pat MacGibbon) Waveguide Splitters for Lower Hybrid Current Drive, Pete Koert Conceptual Design of a New Outer Divertor for C-Mod, Peter Titus Operations ---------- We continued soldering of feltmetal to the TF arm fingers. Forty-five sheet of feltmetal were silver plated last week and have been successfully passed a careful inspection. They will be laser cut into feltmetal pads for the TF arms and legs over the next few days. We now how sufficient feltmetal in house to complete refurbishment of the TF magnet. Work continued on the upgraded LN2 manifold for cooling the magnets. Lower Hybrid System ------------------- We continued thermal and rf simulations of the lower hybrid coupler system, design of rf probes to monitor power in the coupler and provide fault protection, preparations for high power testing of the first copper plated 4-way splitter, and work on the control system upgrade. Diagnostics ----------- The optical table that will provide the primary support for the polarimeter optical components has been setup in the diagnostic lab where full scale tests of the polarimeter system will be performed. The FIR lasers have been installed on the table, and the vacuum and gas handling systems are being brought into operation. The diagnostics neutral beam test chamber is operational. Short beam pulses have been fired into the chamber and heating has been observed on the target plate using the IR camera. Travel and Visits ----------------- Last week, from September 23 to 24, Ron Parker attended the 4th and last meeting of the European Facilities Review Panel in Brussels. The Panel report is nearly finalized, and will become public toward the end of October. Martin Greenwald was in Austin, Tx, from October 1 to 2 for a meeting of the FESAC Alternate Concepts panel. Dennis Whyte and Amanda Hubbard visited OFES last Friday to discuss university input to their strategic planning. Dr Olaf Grulke of IPP-Griefswald and the Ernst-Moritz Arndt University is on-site, continuing a multi-year collaboration with C-Mod on studies of edge turbulence. Dr. Grulke will spend two weeks at MIT now and another two weeks here in December. He is analyzing Gas-Puff-Imaging data from the X-point and outboard midplane regions. In this work he will examine the statistical measures of the turbulence in the two locations, as well as look at the characteristics of the X-point region turbulence across the L-to-H mode transition. He will be working closely with Jim Terry and Stewart Zweben, PPPL. Andrea Garofalo, GA, visited the PSFC on Friday in order to present recent experimental results of rotation drive using non-axisymmetric fields on DIII-D. He met individually with C-Mod scientists for further discussions on this and related topics. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly