Alcator C-Mod Weekly Highlights November 9, 2001 We continued work on the LH MIE Project, removal of the old DNB from the cell, and the new inner divertor. The inspection of the TF and OH coax components continued. Physics ------- Dr. Tomohide Nakano visited this week from Naka, Japan, where he makes spectroscopic measurements on the JT-60U device. He spent most of his week working with Bruce Lipschultz comparing impurity infuxes from JT-60U and C-Mod. There are similarities between the two experiments with regard to low-Z impurities originating in the main chamber. Dr Nakano also spent time discussing divertor impurity sources, and the processes by which they are generated. These processes could lead to differences between the two experiments in that some substantial fraction of the carbon source rate in JT-60U is due to chemical sputtering. Upcoming experiments on JT-60U devoted to better determining the impurity source rates as well as main chamber recycling was the last item discussed, again for comparison with C-Mod. Inspection ---------- We are approximately 75% complete with the TF inspection, still with very good results. Analysis of the OH coax indicates better performance can be obtained by increasing the engagement of the bolts with the helicoils in the OH coil terminals, and increasing the preload on the bolts. How best to implement these changes is now under consideration. Inner Divertor -------------- All inner wall studs are now in place and have been pull tested. In addition, all divertor backing and C-plates are in house and being prepared for installation. We also continued preparations this week for installation of divertor related diagnostics including the new probe array and halo and disruption diagnostics. Lower Hybrid MIE Project ------------------------ PLC and I/O modules were received this week that will allow the completion of the first control and protection cabinet. The pump Controller for the klystron water cooling system is being wired. Communications between the Cart 3 test PLC, the control station PC, and the HVPS was established this week. Data from the HVPS can now be displayed on the control station PC. Water flowmeters were also wired this week. The temporary 208V 3-phase service to transmitter control and supply racks is finished. Testing of the power supplies is expected to begin next week. Faults have been cleared in two of four Transmitter Protection System (TPS) RF boards confirming they are operational. Design of the Circulator/Dummy load water circuit was begun this week. DNB and Related Diagnostics --------------------------- An F-Port flange review meeting was held on Thursday. The purpose of the meeting was to review plans for a revision in the ECE mirror flange, an additional tangential port, removal of an interference between the existing tangential port and the cylinder, and modifications to accommodate a pumped duct. A second meeting was scheduled for next Friday to answer questions raised during this meeting and for final approval of plans and designs. We continue to remove the old DNB components from the cell in preparation for the new RFX beam. Travel and Visits ----------------- Ian Hutchinson and Robert Granetz attended a post-APS workshop on stabilization of MHD, which was held at GA. The primary focus was on using rotation and active magnetic feedback to reduce the amplitude of resistive wall modes (RWM) and neoclassical tearing modes (NTM), which currently limit the maximum beta achievable in a number of tokamaks. Other topics included the use of flowing lithium walls to stabilize the RWM, and theoretical work on RWM's and NTM's. In addition, Ian gave an invited talk on measurements of torque and mode locking in Alcator C-Mod.