A Collaborative National Center for Fusion & Plasma Research

Columbia University

Columbia University

Professor Michael Mauel

PPPL Engineer Steve Raftopoulos assisted Professor Mike Mauel 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 required these components to be installed with greater precision, and Professor Mauel asked for the assistance of PPPL’s metrology engineers and equipment.  The stabilization of MHD in HBT-EB will be benefitted by the greater precision in mounting of the internal components.  Steve Raftopoulos 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 ensured that the shells (each of which is a half of a pair that span the plasma 180 degrees poloidally) would fit against each other and meet at the midplane.  Close collaboration between the PPPL metrology engineer Steve Raptopoulos and the Columbia University staff and students resulted in a measurement strategy that was efficient and yielded good results.  The measurement data was analyzed, organized into groups and exported in IGES format that is readily useful to the Columbia University staff and students.  Installation activities at the Columbia University/HBT-EP facility had the shells installed into the vacuum vessel with the Romer CMM arm as a guiding tool.  The Romer arm was 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.  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 were used for these activities.  All of this work was performed by the staff and students and served as an educational experience into metrology engineering.  

The late PPPL scientist Steve Paul made important contributions to the program, supervising graduate students who were developig and installing diagnostics into HBT-EP.  Paul mentored students working with fast camera imaging, Thomson scattering optics, and D-alpha plasma emission. Along the way he contributed to the educational advancement of the Columbia graduate students.  In addition, Luis F. Delgado-Aparicio has assisted with the design of a multi-filter (multi-color) x-ray tomography diagnostic.


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