Alcator C-Mod Weekly Highlights June 1, 2009 FY2009 weeks of research operations: Target: TBD Completed: 0 weeks Research -------- 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. Operations ---------- Re-assembly of the alternator was completed on 5/27, and the vendor has de-mobilized. We continue to reinstall and checkout instrumentation and exciter bus work. The alternator housing has been filled with helium, the normal operating gas, and heaters have been turned on to bring the alternator up to operating temperature. The oil lift pumps were activated on 5/29, and the rotor is now spinning at 2 RPM. This rotation, over the next few days, will eliminate any "sets" in the components acquired during the several month long inspection. We continued in-vessel work in preparation for pump-down. The MSE is now completely installed, aligned, and calibrated, as are the GPI periscopes and the wall bolometry arrays. We continue installation, alignment, and calibrations of the CXRS systems. Reconfiguration of the Digital Plasma Control System (DPCS) hardware in preparation for the 2009 C-Mod experimental campaign is complete. The control system hardware has been relocated from the three equipment racks formerly used for the old "Hybrid Computer" system into a single enclosure. The host computer has been upgraded from a single cpu to a dual quad-processor (8 cpu) system running the Linux 2.6 kernel. This platform executes the control computations about 2.3 times as fast as the previous system, as well as providing capability for multiple time scale parallel computations. The network interface to the host computers has been upgraded from 100Mb to a 1Gb link. Lower Hybrid Systems -------------------- Work continued on the coupler protection system (CPS) software upgrades for the new launcher. We continued fabrication of the new launcher 4-way splitters and forward waveguide/vacuum windows. Eight of the sixty-four waveguide/window assemblies have been successfully leak-checked. Four have been successfully welded onto the first production 4-way splitter. All sixteen production 4-way splitters have been fabricated with two spare splitters in production. A vendor has been selected for fabrication of the magic tee components for the launcher feed system. Simulation results of the magic tee indicate the power handling capability can be doubled with the new design. Travel and Visits ----------------- Gerrit Kramer, PPPL, was at MIT last week working with Arturo Dominguez on installation of the upgraded reflectometer system. 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'. Robert W. Conn, President of The Kavli Foundation, visited the PSFC on May 29. He met with Earl Marmar for a discussion of fusion research and the Alcator program, and he toured the C-Mod facility. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly