Alcator C-Mod Quarterly
Progress Report – FY09 Q3
The main activities at Alcator C-Mod during the third quarter of FY09 were a reassembly of the tokamak and alternator, and restart of operations.
Alternator Following a routine inspection of the alternator in the summer of 2008, the original equipment manufacturer recommended that the generator rotor not be returned to service. Subsequently, we embarked on a process to re-evaluate the rotor's fitness for service. This process has involved multiple steps: a complete non-destructive evaluation (NDE) re-inspection, including boresonic ultrasound imaging, visual inspection and surface eddy current probing; removal of two bore sample rings; extensive materials testing of the bore samples, including chemical analysis, tensile, fracture toughness and crack growth measurements, and microstructure and fractographic analysis. Two outside companies, experts in the field of generator rotor safety evaluation for the electrical utility industry, were contracted to examine all of the data (both NDE and from the materials samples), and to give their independent recommendations with regard to fitness for service of our rotor. All materials tests showed that the rotor steel has good properties, well beyond the ‘conservative’ assumptions normally used by industry consultants in the absence of actual measurements on a specific rotor. Both outside expert companies have certified that the rotor is fit for continued service, with large margins of safety. A panel of experts assembled by MIT's Vice President for Research has concurred with these findings and recommendations, and the Vice President endorsed return to service for the alternator.
Publications
2009 Nucl. Fusion 49 045009
2009 Plasma Phys. Control. Fusion 51 065006
E. M. Edlund, M. Porkolab, G. J. Kramer, L. Lin, Y. Lin, and S. J. Wukitch, 2009 Phys. Rev. Lett. 102 165003
C-Mod 2009 Ideas ForumThe 2009 C-Mod Ideas Forum was held at MIT from April 6th to 8th. This meeting marks the beginning of our detailed campaign planning process for FY09/10. Participants from MIT and ten other institutions submitted 137 proposals for consideration, spanning a broad range of research areas. The materials presented at the Forum are available online at http://www.psfc.mit.edu/research/alcator/program/ideas2009/agenda_mirror/ideas_forum_agenda.htm
Collaborations Paul Bonoli and Naoto Tsujii traveled to Oak Ridge National Laboratory, May 26 - 29, to work with Fred Jaeger, Lee Berry and Don Batchelor in the Oak Ridge Theory Group. Naoto worked with Fred Jaeger to successfully couple a synthetic diagnostic for Phase Contrast Imaging to the all orders spectral code AORSA. The AORSA solver employs a conductivity operator that is valid to all orders in the ion Larmor radius and is valid for all ion cyclotron harmonics. They ran the AORSA solver for a discharge in Alcator C-Mod with ICRF mode conversion where flow drive had also been measured. Up to 100 toroidal modes coupled by the ICRF antenna spectrum were simulated with AORSA using the massively parallel Franklin computer at NERSC. The fluctuating electron density associated with the ICRF wave was then reconstructed by superposition of the electric field contributions from the individual toroidal modes, with appropriate weighting. Finally this fluctuating density was used in a synthetic diagnostic code for the Phase Contrast Imaging (PCI) Diagnostic. A similar calculation has already been carried out by Naoto using the electric fields computed from the TORIC code which employs a conductivity operator developed in the ion FLR limit, with modifications for treatment of ion Bernstein waves (IBW) and ion cyclotron waves ICW). By comparing the synthetic PCI signals based on the AORSA fields, and the simulated PCI signals based on the TORIC fields with the measurements, it may be possible to validate these models against experiment and thus define under what conditions the simplified conductivity operator used in TORIC is valid.Paul Bonoli worked with Don and Lee to implement the parallel TORIC ICRF solver as a component in the Integrated Plasma Simulator (IPS). The IPS is a parallel framework that has been implemented on the Franklin computer that consists of a communication interface called the "Plasma State" as well as several actuator components, including AORSA, CQL3D, NUBEAM, and now TORIC. A discharge is simulated using a transport code such as TSC which writes it's time dependent output to the Plasma State.The actuator / source codes are then run with parallel implementation using the data stored in the Plasma State. This type of parallel framework makes it possible to perform time dependent simulations of ICRF and NB heating as well as lower hybrid current drive in devices such as Alcator C-Mod and ITER with several day turn around, whereas many days (> 20) may have been required on a serial platform. While at Oak Ridge, Paul worked with Lee and Don to test the parallel implementation of TORIC in this framework. Meetings Presentation titles for the 2009 TTF meeting in San Diego may be found athttp://ttf2009.ucsd.edu/TTFMeetingProgram2009RR.pdf
Several of our engineers presented posters at the 36th International Conference on Plasma Science (ICOPS) and 23rd Symposium on Fusion Engineering (SOFE) last week in San Diego. Rick Murray presented work he has done on the "Upgrade of the ICRF Fault and Control Systems On Alcator C-Mod". Alan Binus discussed "An Intermediate Power Amplifier Upgrade for 40 to 80 MHz Operation of the Alcator C-Mod ICRF Transmitters". Peter Koert presented a poster on the design of our new 4-strap antenna entitled "New Alcator C-Mod Rotated 10 Degree 4-Strap ICRF Antenna". The author index and link to abstracts for these presentations may be found athttp://www.npss-confs.org/icops-sofe/Program/AuthorIndex.asp
ReNew Many scientists affiliated with C-Mod attended the OFES Research Needs Workshop in Bethesda, MD, the week of June 12. From MIT were Amanda Hubbard, Catherine Fiore, Martin Greenwald, Bruce Lipschultz, Earl Marmar, Joe Minervini, Ron Parker, Miklos Porkolab, Jim Terry, and Dennis Whyte. From PPPL were Chuck Kessel, David Mikkelsen, and Randy Wilson. Bill Rowan, UTexas, also attended. Martin Greenwald led the thrust on validated predictive modeling. Jim Terry was leader of the "Measurements" Panel associated with Themes 1 and 2. During the Workshop he chaired the break-out session on research thrust 1 - "New Measurement Techniques to Understand and Control Burning Plasmas". Ron Parker co-chaired the drafting of Thrust 4: "Qualify operational scenarios and the supporting physics basis for ITER" with Craig Petty, GA. This work involved a presentation and editing the final version that will appear in the ReNew report. Bruce Lipschultz was co-leader with Tony Leonard, GA, of the core-edge coupling panel. Amanda Hubbard served as the Chair for Theme II, Randy Wilson was the leader for the Auxiliary Systems panel within Theme II. Joe Minervini led the Magnets panel, and related Thrust, also in Theme II. For the 18th Topical Conference on RF Power in Plasmas in Ghent, invited papers were presented by Lin, "Observation of Flow Drive during ICRF mode conversion experiments in Alcator C-Mod", Parker, "Modification of current profile, toroidal rotation and pedestal with LHCD in Alcator C-Mod", and Wright, "Full-wave simulations of lower hybrid wave propagation in tokamaks". The C-Mod presentations can be found at http://www.psfc.mit.edu/research/alcator/pubs/RF/rf2009index.html
Pat MacGibbon and Peter Koert visited one of our vendors the week of April 6 to discuss transmission line components for the lower hybrid system. John Rice, Catherine Fiore, Martin Greenwald, Jerry Hughes, Miklos Porkolab, Darin Ernst, Liang Lin (now at UCLA), and Bill Rowan, UT-FRC, attended the TTF Workshop in San Diego, CA April 28 – May 1 and presented C-Mod relevant material. Catherine Fiore, Paul Bonoli, and John Wright were in Denver, CO, The last week of April combined APS/Sherwood Theory Meeting. Amanda Hubbard attended a meeting of the Research Needs Workshop Executive Committee in Austin, TX May 5-7. Rick Murray, Alan Binus and Peter Koert attended the 36th International Conference on Plasma Science (ICOPS) and 23rd Symposium on Fusion Engineering (SOFE) the week of June 5 in San Diego. Alan Binus also visited our vendor for new klystrons and replacement ICRF tubes while on the West Coast where he received a detailed update on the status of these components. Catherine Fiore, Martin Greenwald, Bruce Lipschultz, Earl Marmar, Joe Minervini, Ron Parker, Miklos Porkolab, Jim Terry, and Dennis Whyte attended the OFES Research Needs Workshop in Bethesda, MD, the week of June 12.
Bruce Lipschultz was at the divertor/scrape-off layer ITPA meeting in Amsterdam, May 5-8. He is the international chair for this group. Earl Marmar attended the joint meeting of the IEA Executive Committees for the Large Tokamak and Poloidal Divertor Implementing Agreements, May 21-22, at JET. Discussions included recent and planned international personnel assignments, and proposed amendments to the Large Tokamak agreement to effectively combine it with the Poloidal Divertor agreement. Dr. Marmar also delivered a presentation on status and plans for Alcator C-Mod. John Rice attended the 4th IAEA Technical Meeting on the Theory of Plasma Instabilities in Kyoto, Japan, May 18-20, presenting an invited talk on 'Spontaneous Rotation, Reversals and Momentum Pinching'. Tom Fredian and Josh Stillerman attended the 7th IAEA Technical Meeting (IAEA-TM) on Control, Data Acquisition, and Remote Participation for Fusion Research held in Aix en Provence, France. Both presented papers and led an MDSplus satellite meeting. Aaron Bader, Paul Bonoli, Bob Harvey (COMPX), Yijun Lin, Orso Meneghini, Ron Parker, Miklos Porkolab, Andrea Schmidt, Syunichi Shiraiwa, Greg Wallace, Randy Wilson (PPPL) and John Wright attended the 18th Topical Conference on Radio Frequency Power in Plasmas in Gent, Belgium on June 24-26, 2009.
Yijun Lin attended the 36th EPS Conference on Plasma Physics, in Sofia, Bulgaria, the week of June 29. He presented a poster entitled "ICRF Mode Conversion and Flow Drive on Alcator C-Mod".