Alcator C-Mod Weekly Highlights December 15, 2008 FY2009 weeks of research operations: Target: TBD Completed: 0 weeks Operations ---------- Reassembly of the Alcator C-Mod tokamak has begun. The central column was installed on Thursday, followed by installation of the OH support blocks on Friday. OH1 and OH2U thermocouple/voltage signal wire assemblies for the coil side were made, electrically checked and installed; the OH2L tc/voltage signal wire assembly has been electrically checked and is ready for installation. Work continued on the vessel heaters. Four lower vertical port heaters have been replaced and are being cured over the weekend, following which foam insulation will be installed and the port boots re-installed. Silver plating has been successfully completed on all TF arms and all have passed inspection. Work continues on preparing the arms for installation. All lower arms will be ready by the end of this week. All spring packs are ready for TF arm and leg installation. Refurbishment of hardware in the cryogenic plumbing of the TF quadrant cooling system has been completed and pressure tested successfully. The vendor's crew arrived mid-week to begin disassembling the MIT alternator, preparatory to reinspection of the rotor. It should take about 8 days to get the rotor partially removed and ready for ultrasound testing of the collector end. The flywheel coupling has been removed, the motor coupling has been removed, and the drive motor has been moved out of the way. Work will continue over the weekend. IEA/ITPA Workshop ------------------ On December 11-13, the MIT PSFC hosted the Seventh IEA Large Tokamak Workshop (W69) on Implementation of the ITPA Coordinated Research Recommendations. This meeting is a joint workshop held under the auspices of three IEA implementing agreements related to tokamak research: the Large Tokamak I.A.; the Poloidal Divertor I.A.; and the Plasma Wall Interactions in TEXTOR I.A. Attendees included representatives from the international ITER Organization, ITPA topical group leaders, ITPA Coordinating Committee, ITER domestic agencies, the US Burning Plasma Organization, USDoE OFES and tokamak facilities from around the world. The meeting discussions included ITER high priority research needs, ITPA plans to address those needs, and related experiments and modeling. The final two half days of the meeting were devoted to detailed discussions of ITPA joint experiments proposed for calendar year 2009. Participants came to the workshop from the U.S., Europe, Japan, Korea and India. Sessions were also attended through remote teleconference by participants from the ITER Organization site in Cadarache, France. ICRF Systems ------------- We completed testing of the new 10 kW solid state Intermediate Power Amplifier (IPA) and are very satisfied with the performance. The driver input loading was adjusted to improve the impedance match between the IPA and the Driver. The Driver Input tuning was adjusted with a best match of 1.26 VSWR (i.e. reflected power is 1% of forward). The performance is consistent with the expectation that we will have more drive capacity from the IPA (10 kW) than with the previous tube version (5 kW). In addition, the harmonic distortion is significantly less and will lessen potential interference with diagnostics and other systems. Work is underway to install the second IPA into FMIT#3 which should be ready for testing in January. We have sent an anode sample from a failed tube to the vendor for material testing. Further analysis is underway to determine whether geometrical modifications can increase the tube lifetime by factors of 2-3 or if a change in material will be necessary as well. Lower Hybrid System -------------------- Progress was made last week on the Transmitter Protection System (TPS) upgrade. A meeting was held with our SBIR Phase II contractor to discuss progress and review the specification. Related work was also carried out on the collector overtemperature interlock, and discussions were conducted on our planned implementation of this circuit to allow us to share resources with the contractor's TPS hardware/software designs. Progress was also made on the new probe designs using the prototype waveguide with probes. The two probes in the prototype were characterized and analysis is ongoing. We are also arranging digitizer inputs for tests of the I-Q detectors planned for use with these probes. Six new CPS (Coupler Protection System) boards were received from the vendor and have been installed in the CPS rack and configured for testing. Diagnostic Neutral Beam System ------------------------------ The DNB safety systems will be upgraded with the addition of interlock hardware that will prevent access to any of its racks unless the mains power is turned off. A kirk-key system is currently being designed. Travel and Visitors -------------------- Earl Marmar participated in the NSTX Research Opportunities Forum by teleconference, and made a presentation entitled: Alcator C-Mod Research Highlights and Plans Dennis Whyte attended the International High Heat Flux Components Workshop on Readiness to Proceed from Near Term Fusion Systems to Power Plants which was held at UCSD and was jointly organized by R. Raffray of ARIES, R. Nygren of Sandia and Dennis. He presented "Physics gap issues from ITER to reactors for integrating HHFC and edge plasmas". Dennis Whyte also visited GA / DIII-D, where he discussed experimental planning of the 2009 Joule milestone on fuel retention, as well as disruption mitigation experiments for ITER. He also re-presented his FESAC talk to the DIII-D group on "The challenges of Plasma-Surface Interaction for ITER & Beyond". Chris Brunkhorst (PPPL) was at MIT last week to observe testing of our new solid-state IPA. PPPL has recently taken delivery of a similar unit and wished to investigate its compatibility with the driver stage. Alessandro Bortolon and Basil Duval from EPFL visited MIT during the last two weeks to analyze results from the C-Mod/TCV joint experiment carried out May 2, 2008 on rotation inversion. We expect that this analysis there will form the basis for a future publication, as well as a new run plan. Tom Osborne from GA was on-site last week to begin installation of a suite of analysis codes that he had developed for DIII-D. Essentially the codes can retrieve measured profile data, fit the data, average the data at times corresponding to a desired fraction of an ELM cycle, prepare the data for submission to kinetic EFIT which finds equilibria after including kinetic profile data, and run the kinetic EFIT solver. Successful implementation of these codes will enable a far more efficient capability for running kinetic EFIT for C-Mod data and provides an addition profile fitting tool. He worked closely with Josh Stillerman, Jerry Hughes, and Jim Terry. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly