Alcator C-Mod Weekly Highlights March 22, 2002 Reassembly of Alcator C-Mod continued this week. Work on the new RFX DNB and the LH MIE Project continued as did work on diagnostics. Physics ------- A faster (non-parallel, out-of-core) version of the 2-D full-wave ICRF code, TORIC, has been successfully configured to run locally on the new Linux workstations (CMODWS01, 02 and 03). Up to 161 poloidal modes have been run with CPU time of about 400 minutes, which is comparable to run time on the CRAY. Runs with higher mode number appears to be limited by available scratch disk space on the Linux stations. Some preliminary physics runs have shown the mode conversion process in D:He3 and H mixture may be much more complicated than previously thought. J. Snipes, M. Greenwald, and T. Fredian attended the ITPA Confinement Threshold and Modeling Database meeting at PPPL the week of 11 - 14 March. The latest results of the Confinement and Threshold Database Working Groups were presented. The L-mode database has moved from Garching to Cadarache where it will be managed by G. T. Hoang. New low aspect ratio MAST data has just been added to the database and initial regression fits indicate that the data do not change the density, toroidal field, and plasma surface area dependencies very much, but add an aspect ratio dependence of (a/R)^0.46. Joseph Snipes was asked to present the latest results from the Confinement and Threshold Database Groups at the IAEA meeting. Operations ---------- Following installation of all the upper TF springplates, another successful hi-pot of the TF was done. This test was required before installation of the TF legs could proceed. However, reassembly of the machine was delayed somewhat this week when the boots that seal the cryostat were found to need modifications to allow for more insulation and more space around the vacuum flange. These new boots have to be installed before the TF vertical legs. Five of the ten required new boots have been fabricated, and two of the TF legs have been installed. Pumpdown is now scheduled for the week of April 22, approximately 4 weeks later than indicated on the original schedule generated in August 2001. Lower Hybrid MIE Project ------------------------ The transmitter wiring is progressing. Only one more wiring harness is needed to complete transmitter #3. Connections to Cart #2 are approximately 50%, and those to cart #1 are about 20% complete. The klystron high voltage cable is also being installed. The nitrogen waveguide pressurization plenum is being fabricated. Termination of fiber-optic data and control cables is nearly complete. Both cooling water pumps for the LH system are now operational. ICRF Systems ------------ Work continued on the testing and calibration of the approximately 35 demodulator boards required for the ICRF diagnostic and protection systems. Peter Koert was in Germany this week working with the vendor who will supply the fast ferrite tuners. He hopes to procure sufficient documentation to allow control and protection circuitry to be designed and fabricated at MIT for the prototype unit. DNB and Related Diagnostics --------------------------- Operation of the RFX DNB injector began last week, 20 days after the Budker team arrived from Novosibirsk. Beam parameters were rapidly brought up to the full specification operating values of 50 kV, >50 ms pulse duration, and >4.5 amps of ion current (simultaneously). About 500 pulses have been fired during the first week of operation, and the injector reliability is extremely high. Calorimetry measurements show that the beam has a 1/e diameter of 6 cm at the exit of the injector, and should be even smaller at its focus inside the tokamak. Comparisons of calorimetry data with the dump magnet on and off indicate that full-energy neutrals are the predominant beam component. Spectroscopic measurements of the component fractions are in progress. The beam is now routinely fired remotely under MDSplus control, and work continues this week on interfacing the data acquisition directly to our MDSplus trees. Diagnostics: ------------ At PPPL, the 140 GHz reflectometer channel has successfully been changed into a fixed frequency channel, bypassing the malfunctioning Gunn diode. This modification now gives us two fixed-frequency channels, at 140 and 130 GHz, for edge pedestal fluctuation measurements. Also at PPPL, fabrication of the remaining BES/MSE fiber optics ferrules continued this week; they should be completed next week. EDM machining of a new BES/MSE image bisector block has begun, with completion expected by the end of April. Schott Glass USA has been contacted about new SFL6 glass vacuum windows for this diagnostic. At MIT, we continue to work on the MSE optics, CXRS telescope and shutter system, new wide angle cameras, Penning gauges, and divertor probes. Travel and Visits ----------------- Martha Redi, PPPL, was here this week as part of the PPPL collaboration on investigating the gyrokinetic stability of the Alcator C-Mod ITBs. This work will be presented at the upcoming Transport Task Force meeting. Stew Zweben, PPPL, was also at MIT for the week, working on upgrades to the Gas Puff Imaging diagnostic. Martin Greenwald attended the ESnet steering committee meeting at the Jefferson Lab, Newport News, Virginia this week.