Diagnostic Overview for Non-Solenoidal Startup Experiments on Pegasus-III

The diagnostic set for initial experiments on Pegasus-III is designed to quantify the efficacy of DC helicity injection and microwave injection as approaches to non-solenoidal tokamak startup. The initial set of diagnostics commissioned include: strain gauges to monitor magnet stresses; internal magnetics operated with an internal toroidal winding for calibration; Rogowski coils used for feedback control; injector voltage and current measurements calibrated during power supply commissioning; a fast ion gauge calibrated against a capacitive manometer used to measure injector gas valve flow rates; visible emission and imaging to identify cathode spot formation during injector conditioning; and a visible survey spectrometer used for impurity identification and visible bremsstrahlung measurements. Radiation measurements from an AXUV diode array and VUV spectroscopy are used with STRAHL simulations to quantify impurity dynamics. Additional measurements of n_e and T_e from Thomson Scattering can constrain equilibrium reconstructions. Microwave imaging is being developed for optimizing the launch angle and quantifying mode conversion efficiency for electron Bernstein wave injection.