Auburn University CTH and W7-X Research Progress and Plans*

The Compact Toroidal Hybrid (CTH) is a torsatron/tokamak hybrid. The main goals of the CTH experiment are to study disruptive behavior as a function of the applied 3D magnetic shaping, and to test and advance computational tools able to describe 3D MHD physics such as the V3FIT reconstruction code and NIMROD modeling of CTH. Recent non-resonant divertor experiments, vertical stability, and hard x-ray generation studies will be overviewed and their relevance to tokamaks and quasi-axisymmetric stellarators will be discussed. Ongoing diagnostic development for the experiment includes development of new Hall probe array measurements, new spectroscopic studies of W and other high Z materials, and development of a neutral Argon density spectroscopic diagnostic. CTH also serves as a test bed for diagnostic development for our collaborations on the larger facilities like DIII-D and W7-X. Auburn research on W7-X will be summarized including the development of a new coherence imaging ion temperature measurement, study of drift effects on divertor operation, plans for plasma edge Tungsten optical measurements and core Tungsten transport experiments using x-ray spectroscopy.