Equilibrium Reconstruction using Soft X-Ray Chordal Diagnostics on the Compact Toroidal Hybrid Experiment

Equilibrium reconstructions using the V3FIT code will be presented for current carrying plasmas on the Compact Toroidal Hybrid (CTH) torsatron experiment (R = 0.75 m, a ~ 0.2 m, B <= 0.7 T, ne <= 10¹⁹ m-³, Te <= 250 eV). The reconstruction input data set includes the Soft X-Ray (SXR) chord signals normally used for tomographic reconstructions. Four cameras, each consisting of a 20-channel AXUV-20EL photo-diode array view the CTH plasma through 2 μm Be foil. Three cameras view the plasma at one symmetry plane (ϕ = 36°) while the fourth views the plasma at another symmetry plane (ϕ = 0°) , one-half field period away. When observed, sawtoothing provides additional constraints to reconstructions. The reconstructions assume uniform SXR emissivity on a flux surface. The SXR signals provide additional data inputs to V3FIT, which has primarily used magnetic data to fit the equilibrium.

Work supported by US. Department of Energy Grant No. DE-FG02-00ER54610.