Alcator C-Mod Weekly Highlights January 25, 2002 Assembly of C-Mod continued this week with installation of the lower TF arms. Work continued on ICRF, LH MIE, DNB, and diagnostic systems. Physics ------- At the weekly physics meeting, Robert Granetz presented some initial results involving analysis of x-ray tomography of ITB plasmas on C-Mod. It may be possible to use the shapes of the reconstructed x-ray emissivity contours to measure the q-profile near the axis. Recent ITB plasmas on C-Mod exhibit extremely peaked x-ray emissivity profiles, which makes this technique feasible near the magnetic axis (in an earlier study, on ohmic L-Mode plasmas, the technique was found not to be applicable). These new preliminary results appear to determine elongation near the center to an accuracy of +/-0.03, which would correspond to an error in q0 of +/-0.1. Tomographic analysis of high performance eda H-Mode plasmas also shows promise. Operations ---------- Assembly of C-Mod continued this week with the installation of 6 out of the 20 lower TF arms. All arms are inspected carefully, hi-potted, and thermocouple and voltage tap instrumentation is checked before installation. Fitup and testing of the new springplate insertion tool has begun. We continued setting up for machining the cylinder this week. Fabrication of the new cryostat ports by an outside vendor is on track for a late Feb delivery. Development of the drive amplifier and some small machining operations for the new MHD antennas continued. Lower Hybrid MIE Project ------------------------ Commissioning of the HVPS is well underway. The primary power supply transformers were energized to 13.8 kV this week with the modules initially disconnected. Following this initial test, the modules were reconnected and testing continued. The snubber, voltage divider, and triax inner conductor were hi-potted successfully to 60 kV with low leakage current. Testing of the high voltage dummy load wiring is in progress. Fabrication of control and protection circuit boards, development of PLC software, preparations for installation of the remaining klystron carts, development of the phase and amplitude control software, and work on the water cooling system all continued this week. ICRF Systems ------------ After achieving very good results with the phase measurements, careful tests of the amplitude detection section of the new demodulator board are in progress. Both the amplitude and arc detector step response is less than 1 us. These fast response times will limit the damage done by any antenna or transmission line fault condition to harmless levels. Machining of the D and E-Port antenna Faraday shield and the J-Port antenna straps are continuing in house. DNB and Related Diagnostics --------------------------- Planning and design for the initial installation and commissioning of the RFX beam is largely complete. We are ready to start modifications to the beam support frame to accommodate the new beam. Though not required for beam commissioning, the F-port flange has been approved for machining. Information has arrived from the Budker Institute team regarding the interface of the beam control software with MDSPlus. This information will be used to begin work on the software that will transfer the beam parameters to MDSPlus on a shot by shot basis. The PLC rack has been cleared of all old cabling, and new wiring is in progress. Once the PLC is wired to the cross connect blocks, we can begin installation of the vacuum controllers and other rack mounted equipment. At PPPL, mechanical/optical work continued on the MSE diagnostic in preparation for reassembly and testing next week. Travel and Visits ----------------- Steve Wukitch, Jim Zaks, Dave Terry, and Montgomery Grimes attended SOFE this week in Atlantic City, NJ. Steve presented an invited talk on C-Mod with an accompanying paper. Jim, Dave, and Montgomery all presented posters, also with accompanying papers. Peter Titus, PSFC Fusion Engineering and Technology Division, also discussed analysis results of our divertor and antennas. "Results and Status of the Alcator C-Mod Tokamak", S. Wukitch, B. Beck, E. Fitzgerald, R. Granetz, D. Gwinn, M. Grimes, J. Irby, D. Terry, P. Titus, R. Vieira, S. Wolfe, J. Zaks, and the Alcator C-Mod Group, MIT-PSFC, and S. Bernabei, R. Ellis, L. Gehrig, J. Hosea, D. Loesser, G. Schilling, J.R. Wilson, PPPL "Inner Divertor Detailed Design and Manufacturing", J. Zaks, M. DeMaria, B. LaBombard, R. Granetz, E. Fitzgerald, H. Savelli, P. Stahle "The Alcator C-Mod Lower Hybrid Current Drive Experiment Transmitter and Power System", M. Grimes, D. Gwinn, R. Parker, D. Terry, MIT-PSFC, and J. Alex, Thales AG "The Alcator C-Mod Lower Hybrid Current Drive Experiment Low Power Microwave and Active Control System", D. Terry, W. Burke, M. Grimes, D. Gwinn, J. Irby, N. Kambouchev, R. Parker, P. Woskov "Disruption Load Calculations Using ANSYS Transient Electromagnetic Simulations for the Alcator C-Mod Antenna", P. Titus "Alcator C-Mod Inner Divertor Upgrade Design and Analysis", P. Titus, J. Zaks, M. DeMaria, B. LaBombard, R. Granetz, J. Irby, B. Lipschultz, E. Fitzgerald, R. Childs, W. Beck, W. Burke, E. Marmar, D. Gwinn, I. Hutchinson, R. Boivin In addition, work on the Lower Hybrid system being done at PPPL was discussed in three papers: Design and Engineering of teh Alcator C-Mod Lower Hybrid Current Drive System", G.D. Loesser, J. Rushinski, S. Bernabei, J.C. Hosea, J.R. Wilson, PPPL, and B. Beck, R. Parker, MIT-PSFC "A Third Generation Lower Hybrid Coupler", S. Bernabei, J. Hosea, C. Kung, D. Loesser, J. Rushinski, J.R. Wilson, PPPL, and M. Grimes, R. Parker, MIT-PSFC "Compact Probe Design for the Power Monitoring Fromt he Narrow Side of the Reduced Waveguide", C. Kung, S. Bernabei, J. Gumbas, N. Greenough, E. Fredd, PPPL