Alcator C-Mod Weekly Highlights March 30, 2001 Work continued on modifications to the J-Port antenna and ICRF control system. The DNB, inner divertor, and Lower Hybrid MIE projects all moved forward this week. ICRF Systems ------------ All ebeam welding of the striplines has been completed. Final machining operations are now being done on the components. An 0.0005" layer of copper will be plated on the striplines early next week followed by a vacuum bake. A picture of one of the long stripline can be seen at http://www.psfc.mit.edu/cmod/operations/EngImages/RF/ICRF/P0001408.JPG The last of five diagnostic access holes in the J-Port flange has been completed. Invessel cleanup inside the port can now begin in preparation for installation of the antenna. We expect reassembly of the antenna to begin within the next 10 days as scheduled. All six of the B-dot probes for the J-Port antenna have been fabricated. An absolute calibration of the probes will be done over the next few days. Invessel cabling and cable clamps are being installed for the probes. Small adjustments to the auto-tuning PLC program were completed this week. This system is now operational. Changes to the ICRF tuning components can be made from the VAX workstations with a direct link from the tuning program. The prototype phase demodulator board has been sent out for fabrication. However, improvements are also being made to the PPPL demodulator modules to improve their phase response during fault conditions over the next run period. We continue maintenance and upgrades to the #1 and #2 transmitters. DNB --- The automatic mode for the DNB was brought into operation this week and the time between pulses decreased from 150 to 120 s. Data for the arc current overshoot was taken. An anticipated strong dependence on the time between the prepulse and the main pulse did not materialize. The overshoot does change with the time between pulses, but is not eliminated. We will continue investigation of the overshoot by making correlations with spectral measurements of the arc plasma and by monitoring it as a function of conditioning time. Lower Hybrid MIE Project ------------------------ More testing of the active controller was done this week. A loop test summing amplifier was built so that we could add an error voltage to the closed loop to test the PID program calculations. We did some tests with both square wave and sine wave perturbations and were able to show that the program is working correctly. The high yard protection systems are being reviewed and work is underway to verify that the existing cabling and breakers are acceptable for supporting the new LH systems, and that we will be able to set the protective relays for proper coordination. A meeting was held with MIT this week to finalize the schedule for the MIT funded LH site modifications. Details of the Hi-Yard changes and work to be performed in the cell were discussed. Work continues on the klystron carts. Inner Divertor -------------- Tiles continue to arrive and proceed through QA. We now have all the upper and lower transition tiles. The vendor is on schedule fabricating the rear girdle plates. They have stress relieved all plates to prevent movement after machining. Another vendor has nearly completed machining of the ribs on all the C plates. This process is the most difficult of the machining operations and provides the keys to limit motion of the tiles. High strength bolts and nuts continue to arrive and undergo testing. Power Systems ------------- Modifications to the EF1U-L commutation bank have begun. The other banks are now complete except for installation of a few recently repaired capacitors. Diagnostics ----------- A laser will be loaned to MIT from UT-FRC for cold pulse experiments during the continuation of the current run campaign. This laser was used on TEXT for the same type of experiments. It was taken out of storage and tested recently at UT-FRC. The laser is now packed for shipping and should arrive for installation and commissioning prior to the resumption of experimental work. The first of the CXRS shutter parts was delivered by the MIT Central Machine Shop. Other parts are being fabricated in the Alcator and UTex shops as we press to get the shutters installed invessel. Travel and Visits ----------------- Stewart Zweben visited this week from PPPL to discuss upgrades to his fast imaging fluctuation diagnostic. Jim Irby visited PPPL last week for discussions with Douglas Loesser, Randy Wilson, Stefano Bernabei, and Gerd Schilling on the Lower Hybrid Launcher. He also met with Raffi Nazikian and attended a PPPL/MIT proposal review of the reflectometry collaboration.