Alcator C-Mod Weekly Highlights February 9, 2001 The Alcator C-Mod Program Advisory Committee Meeting took place last Monday and Tuesday. On Wednesday and Thursday a Preliminary Design Review for the Lower Hybrid Project took place. We continue to work on the J-Port ICRF antenna redesign, and the Lower Hybrid project. PAC Meeting ----------- The Alcator C-Mod Program Advisory Committee met at MIT on 2/5 and 2/6. Talks were given by the C-Mod staff detailing the physics results and physics and facility goals. On the committee were Ben Carreras (ORNL), Philip Efthimion (PPPL), Ray Fonck (UW), Claude Gormezano (Frascati), Tony Leonard (GA), Ed Synakowski (PPPL), and Mike Mauel (Columbia). Rostom Dagazian attended from DOE. The committee was asked to evaluate the overall progress, priorities and balance in the present C-Mod program. They were also asked to assess the links between experiment and theory, and our progress and plans for the ICRF and DNB programs. Lower Hybrid Project -------------------- On 2/7 and 2/8 of this week the Lower Hybrid PDR was held at MIT. The review panel consisted of Tim Bigelow (ORNL), Tom Intrator (LANL), Nevell Greenough (PPPL), Steve Knowlton (Auburn), and Claude Gormezano (Frascati). Both T.V. George and Rostom Dagazian represented DOE at the review. The MIT group presented both overall plans and some details of the power, control, timing, and data acquisition systems. They also presented results from the klystron test stand indicating the status of all 16 tubes. The PPPL group presented extensive details of the launcher design. We have now run some preliminary control loop tests on the NI PXI controller for LH that will be used to control the amplitude and phase of the klystrons. Using the standard PID, we achieved 8 channels of control with a 3 kHz sampling rate. Upon optimization, we were able to reach a 4.4 kHz sampling rate. ICRF Systems ------------ A great deal of work was done on the J-port antenna modifications this week. Nearly all machining of the antenna back plate was completed. Prototypes of the new stripline components have been machined and assembled. We are currently investigating the most efficient way to machine the final inconel-625 components. We are developing an acoustic arc detector for the ICRF system to locate arcs in long sections of transmission line. The process of finding arcs has generally been a very time consuming task that the new detectors should alleviate. We now have two receiver channels in operation. A generator that can produce from 2 to 20 J arcs has also been brought into operation for testing the detectors. The test transmission line is now being assembled. Maintenance and refurbishment of all four transmitters continue in preparation for the next plasma operating period. DNB --- After extensive improvements to the gas fueling system, the water component in the beam has been reduced to less than 4%. Preparation for the PAC and the upcoming DNB Review has precluded work on reducing this component further. The time variation of the component mix together with the beam width have been extracted from data taken during plasma discharges from last December. They indicate that both the width of the beam and the full energy component degrade slightly during the beam pulse. We are following up on this result as a path to better performance as beam operation continues this week. Inner Divertor -------------- The backing plate components have now been rough EDM cut and are being prepared for machining of the holes and keyways. One hundred reworked tiles arrived in-house and are being checked through Q/A. These tiles, which originally did not meet spec, now appear to be satisfactory. Tile support plates continue to arrive. The high strength bolts for attaching the C-plates to the backing plates have been age hardened by a local vendor. Visitors and Travel ------------------- Ron Bravenec (UT-FRC) visited this week and attended the PAC meeting. PPPL was well represented at both the PAC Meeting and the Lower Hybrid Review. Rich Hawryluk, Ned Sauthoff, Joel Hosea and Gerd Schilling attended the C-Mod PAC Meeting this week. Stefano Bernabei, Doug Loesser and Skip Schoen also from PPPL made presentations at the Lower Hybrid Project Review. Also attending the review from PPPL were Joe Rushinski, Joel Hosea, and Gerd Schilling.