Alcator C-Mod Weekly Highlights March 9, 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. A design review was held on a new CXRS shutter. ICRF Systems ------------ Inconel stripline components for the J-Port antenna modification are being produced both in our shop and by two EDM vendors. We expect to have all components complete and ready for plating within the next two weeks. Modifications to the Faraday shield are complete, and the shield has been assembled successfully on the test stand. Work on the new dB/dt RF probes for the antenna also proceeded this week. Four of the six probes are ready for calibration. Fabrication of the remaining two that will be mounted on the antenna septum is nearly complete. A change to the IPA drive point location and installation of a matching transformer greatly reduced the drive power required for this stage of the transmitter. Saturation of the IPA stage limited transmitter performance somewhat during the last run period. Similar improvements will be made as needed to the other transmitters. We have modified the new demodulator board layout per manufacturer recommendations and are awaiting new quotations for these boards. The RF components and modules used in our fault detection system are being carefully tested and parameterized. These systems currently require very time consuming recalibrations for each frequency change. We are investigating both programmable modules to make automatic gain adjustments, and changes to the electronics and cabling to increase bandwidth so that manual recalibration is not required. A PCI based data acquisition system has been setup. This system will provide very fast data logging of forward and reflected power and other fault indication signals. Testing has begun to verify that all channels are working. Work has started on the auto-tune system which links CAMAC analog outputs with PLC inputs. Software is in progress and the associated patch panel installation and wiring has started. DNB --- A design review was held for shutters to be installed invessel to protect CXRS optics. It was strongly suggested by the DNB Review Committee that this work be done during the current up to air. The basic design was approved. A number of suggestions for improvement were made during the review and are being implemented. Lower Hybrid MIE Project ------------------------ We finalized the design of the anti-alias filters for the D-Traq digitizers to be used as part of the lower hybrid data acquisition system. The SFOL transmitter was completed, and we have begun testing the SFOL receiver. The SFOL link must be operational soon so that closed loop tests of the active feedback system can begin. Programming of the active feedback loop is proceeding. As we approach a control program with realistic input, output, and processing modules, an assessment of the ultimate control system speed will be made. A network problem with the PXI chassis was resolved this week. Data characterizing operation of the vector modulator and I/Q detector operation has been taken. Both the vector modulator and the I/Q detector are performing as expected. The network analyzer will be used to make more accurate measurements for comparison with our test program results. Representatives from C-Mod, MIT, and SMMA (the contractor hired by MIT), met this week to discuss the electrical work that will be needed during lower hybrid site modifications. The proper breakers to use, cabling required, and cable runs have been agreed upon. Electro-Mechanical design of the transmitter equipment rack is nearing completion. We have been notified by the vendor that the contract for the klystron circulators is in place. Work is proceeding on klystron cart modifications and wiring, and work has also begun on modifications to the equipment racks. We have ordered the EMI/RFI protected cabinets for the transmitter racks. Power Systems ------------- The work on the EF1 commutation switch capacitor bank continues. The machining of the extrand supports is in progress. Preventative maintenance of power supply control boards continued. Inner Divertor -------------- Over 150 upper transition tiles were received from our vendor this week. A successful test fit of these new tiles into our rear and c-plate mockups was done shortly after their arrival. Dimensions of ten tiles will be computer checked as part of the QA process developed for the tiles. The vendors supplying the rear and c girdle plates are still on schedule. A picture of one of the rear backing plates can be seen at: http://www.psfc.mit.edu/cmod/operations/EngImages/MACHINE/Divertor/Rear_girdle_02.jpg Note that none of the ribs that will lock the tiles into position have been machined into the plate as yet. Travel and Visits ----------------- Phil Ryan visited from Oak Ridge this week to look at J-port antenna components and get drawings and measurements needed to model the antenna.