Alcator C-Mod Weekly Highlights March 16, 2001 We continued to maintain transmitters and power systems, develop Lower Hybrid systems, and fabricate new J-port antenna components. Work is proceeding on improvements to the ICRF control system. Work continues on the new inner divertor. A design review of changes to the J-Port antenna was held. ICRF Systems ------------ We expect all inconel components for the J-Port antenna modifications to be in-house by early next week. Some machining and finishing in our shop to the components will be required before they can be welded, plated, and baked, at which point they will be ready for installation. E-beam welding tests are being done to inconel samples, and fixturing is being developed to support the welding of the actual components. Our hydraulic press was used to successfully bend the two long inconel striplines into the proper shape. Several fiber views of light from possible plasma discharges around the striplines are being planned. We also expect to make a pressure measurement at this location. Designs for the fiber periscopes, and pressure sampling tube are being produced. New holes in the horizontal flange for these measurements will be drilled over the next few days. Components for the diagnostics are being made in-house. On Wednesday, 3/14, a final J-Port antenna review was held via video conference. Steve Wukitch presented details of the problems we had with the antenna, and the changes we are making to allow full power performance during the next run period. Steve's presentation can be found at www.psfc.mit/people/wukitch/antreview.pdf Attending the review were: ORNL Phil Ryan Rick Goulding PPPL Gerd Schilling Bob Ellis GA Bob Pinsker C-Mod Steve Wukitch Rejean Boivin Jim Irby Peter Titus Bruce Lipschultz Brian Labombard UTexas Perry Phillips There was general agreement on the antenna modifications. There was also strong agreement that phase measurements with fast time response are essential. These measurements are being implemented, and the antenna will not be operated without them. Since the modifications require supporting the antenna at the top and bottom from the center of the antenna, a concern was raised about thermally induced stresses. FEA analysis of the antenna performed following the review indicates that these stresses are in fact small. We continue to perform maintenance and inspections of the transmitters. FMIT#3 was brought up to full power into a dummy load this week. However, during these tests, a new intermediate power amplifier tube failed after approximately 10 hours of operation. An older spare tube is being installed and the new tube is being sent out for evaluation. Extensive tests of the IPA protection circuits and cooling systems indicated all were functioning properly. Diagnostics ----------- UT-FRC and U. Idaho personnel are continuing bench measurements to determine the precise spatial resolution of the antenna for the High Resolution ECE heterodyne system. Based on the initial results, a new waveguide with improved resolution was designed at UT and is being fabricated at UT for installation prior to the end of the current down period. DNB --- The detailed shutter design for the CXRS toroidal optics was completed. Parts for the shutters and their actuation mechanisms were ordered with the expectation of delivery next week. Detailed drawings have been given to the Alcator machine shop for manufacture. Lower Hybrid MIE Project ------------------------ We continue to develop the active controller program. Work this week involved primarily more work on the input/output routines, together with another set of routines to set limits for the I/Q detectors. We continue to prepare the three klystron carts for operation. Measurements are being made in the cell to verify that columns for the new mezzanine to support the klystron carts will not interfere with other equipment in the cell. A meeting was held on 3/16 to decide which port the first launcher would occupy. Power Systems ------------- The machining of the support structure for the EF1 capacitor bank has been completed. Signal cabling for ground current monitoring of the commutation banks is being installed. We have begun to setup for testing and calibration checks of all commutation switch Rogowski coils. Inner Divertor -------------- Inner vessel wall tiles and support plates were removed this week to check stud alignment in preparation for the new inner divertor installation. Our rapid prototype plastic divertor components were installed successfully. Pictures of the fit-up can be found at http://www.psfc.mit.edu/cmod/operations/EngImages/CmodImages.asp?ref=/MACHINE/Divertor/ Tiles and other divertor components continue to arrive. Travel and Visits ----------------- Earl Marmar, Ron Parker, and Miklos Porkolab attended the DoE Budget and Planning Meeting March 13 to 15 in Gaithersburg. Earl and Ron gave talks on C-Mod and the LH MIE Project. The viewgraphs from these talks can be found at http://www.psfc.mit.edu/cmod/sciprogram/CMod_Budget_Meeting_Presentation.pdf Amanda Hubbard gave a talk at California State University of Sacramento on Thursday, 3/15, as part of the APS/DPP Distinguished Lecturers in Plasma Physics series, entitled "Understanding and Improving Energy Transport in Fusion Plasmas."