Alcator C-Mod Weekly Highlights January 10, 2005 FY 2005 weeks of research operation planned: 14 weeks, completed: 0 weeks. We are currently up-to-air. Our primary up-to-air goal of installing the lower hybrid launcher has been completed. Final alignments and calibrations of in-vessel diagnostic systems are now underway in preparation for pump-down. Maintenance and upgrades to diagnostic and power systems continue. Operations ---------- Final installation and torque checks of the outer divertor modules containing the new tungsten brush tiles have been completed. Pictures of one installation can be seen at http://www.psfc.mit.edu/cmod/operations/EngImages/INVESSEL/2004/DCP_2044.JPG and http://www.psfc.mit.edu/cmod/operations/EngImages/INVESSEL/2004/DCP_2041.JPG Lower Hybrid System ------------------- The lower hybrid forward waveguide (fwg) has been installed on C-Mod, and all vacuum seals successfully leak-checked. The rear waveguide (rwg) has been placed on its rails and aligned relative to the fwg. The lower hybrid limiters have been trimmed radially and vertically to within 1 mm of their design positions. The launcher radial position drive system has been used to align the couplers with the limiters as a calibration of the launcher position. The launcher can be moved back several centimeters behind the limiters as will be required for coupling experiments. A picture of the launcher and limiters can be found at http://www.psfc.mit.edu/cmod/operations/EngImages/RF/lower_hybrid/DCP_2031.JPG The new Langmuir probes, located between the couplers, can also be seen in the picture. These will be used to measure directly the plasma density at the mouth of the waveguide array, which is one of the important parameters affecting coupling. We have begun installation of the launcher PLC/PC system. This system will monitor launcher temperatures, control cooling and gas purge systems, and control the launcher position. Modifications to the third of four filament instrumentation racks have been finished. Installation of the racks into the klystron cart will begin this week. Power-up checkout tests of the Coupler Protection System (CPS) have begun. Cabling, PLC/IO hardware and software, PC display, and RF fault cards are all being brought into operation. Work continues on LH probe assemblies. Fifty-six probe boards are complete and ready for installation in the new housings. We continued preparations for installation of the waveguides between the klystrons and the rwg. All waveguide components that are mounted on the rwg including splitters and phase-shifters are being inspected and prepared for installation. ICRF System ----------- We continued bringing the FMIT transmitters back on-line. New rf choke inductors which are designed to eliminate corona discharge in the FPA high voltage leads have been fabricated. Preparations are being made to test the transmitter crowbar systems. All new FPA tubes have been installed. Work continued on the FFT power system. Long Pulse DNB -------------- We are reworking the DNB PLC for the control of the new power system, and also reviewing all PLC documentation. Several new status inputs for the LimitAmp and 4160 breaker have been added, and control outputs for the LimitAmp contactor have been added. A new interface screen for DNB power control has been developed. Testing of the power systems should begin within the next few days. The new Long Pulse DNB has passed all final tests, and the Russian team expects to ship the DNB from Novosibirsk in one to two weeks. Diagnostics ----------- We have completed calibration of the in-vessel linear polarizer for the MSE diagnostic. This polarizer can be rotated in front of the plasma-facing MSE optics to generate linearly polarized light of known polarization angle. The reproducibility of the measured polarization angle is better than 0.01 degrees for the outer viewing channels, which is sufficiently good to measure the effects of stress-induced birefringence and Faraday rotation in the MSE system. We continued calibrations and alignments of several diagnostics last week. Proper alignment of the polarimeter retro-reflectors was verified with the new flange and window in place. A rotating laser beam was used to check proper operation of the refurbished AXUV diode array and its associated wiring and electronics. Spectroscopic fiber views were checked in-vessel. The visible continuum array camera was reinstalled and an in-vessel alignment calibration was completed. The in-vessel components for the high pressure gas puff disruption mitigation system have been fit-up and are ready for installation. Work was completed on the Langmuir probe bias amplifiers with double the output current of the previous units. The C-Mod cell was locked down for a neutron calibration run that extended from Sunday afternoon through Monday morning. _______________________________________________ Cmod_weekly mailing list Cmod_weekly@lists.psfc.mit.edu http://lists.psfc.mit.edu/mailman/listinfo/cmod_weekly