Soft X-Ray Diagnostics on the Compact Toroidal Hybrid (CTH) Experiment

Soft X-Ray (SXR) systems are used on the CTH experiment for tomographic reconstruction of the emissivity profile and electron temperature measurement. The emissivities from the multi-chord arrays will also be incorporated into reconstruction of the 3-D flux surfaces of the CTH stellarator plasma. SXR tomography is performed with 3 cameras, each consisting of a 20-channel AXUV-20EL photo-diode array filtered with 500nm Al-foil in a poloidal cross-section. The SXR electron temperature diagnostic is a single chord system viewing the plasma simultaneously in 3 energy bands discriminated with filters of different thicknesses. Ratios of the photo-diode signals are used to infer the maximum electron temperature along the chord, subject to issues of impurity lines. Lastly, a vertically-viewing, 20-chord SXR system has been installed and will be used to infer the Shafranov shift of the plasma. A description of the SXR tomography cameras, the tomographic reconstruction technique, and results will be presented.