Columbia University
Professor Michael Mauel
Engineer Steve Raftopoulos assisted Prof. Mike Maul with the upgrade of the HBT-EP experiment. The upgrade involved installing a new conducting first wall shell that is instrumented with magnetic sensor arrays. The HBT-EB research group believes that these components could be installed with greater precision with the help of PPPL’s metrology experience and equipment. The stabilization of MHD in HBT-EB will be benefitted by the greater precision in mounting of the internal components. Raptopoulos has completed measurements of the Columbia University/HBT-EP Conducting Shell and Sensor arrays. Each shell's geometry was measured, then "best fit" to the CAD geometry. The as-built condition of the shells required the best fit to be dictated primarily by the shell's mid-plane edge and cutouts. This will ensure that the shells (each of which is a half of a pair that span the plasma 180 degrees poloidally) will fit against each other and meet at the midplane. Close collaboration between the PPPL metrology engineer and the C.U. Staff resulted in a measurement strategy that was efficient and has yielded good results. The measurement data is in the process of being analyzed, organized into groups and exported in IGES format that is readily digestible by the C.U Staff. Installation activities at the Columbia University/HBT-EP facility are planned to start during the last week in July. The shells will be installed into the vacuum vessel, possibly with the Romer CMM arm as a guiding tool. Access is limited, therefore the ability use the arm to guide the shells to location will be determined in the field. At a minimum, the Romer arm will be used to determine the "as-installed" location of the shell, by aligning to a set of monuments (on the outward facing side of the shells) that were measured when the shells were being characterized. If time allows, additional measurements can be made, including the position of vacuum vessel segments, TF coils and other HBT-EP features of interest. The Laser Tracker, with it's ability to set up a global coordinate system within the HBT-EP experimental room would most likely be used for these activities. Recently, Steve Paul has been supervising graduate students developig and installing diagnostics for HBT-EP. Paul mentored students working with fast camera imaging, Thomson scattering optics, and D-alpha emission. Along the way he has contributed to the educational advancement of the Columbia graduate students. Steve is also exploring the possibility of a loan of a 16-element x-ray diode array that is a PPPL spare. In addition, Luis F. Delgado-Aparicio has helped with the design of a multi-filter (multi-color) x-ray tomography diagnostic.
