Magnetic Reconnection and Ion Heating Experiments with Compact Toroid Injection in Tokamaks on the Madison Symmetric Torus

Compact toroid (CT) injection has been used in a range of plasma confinement devices for core fueling and magnetic helicity injection. A CT injector has been installed on the Madison Symmetric Torus (MST) with the goal of generating and observing localized ion heating due to magnetic reconnection of an injected CT with a tokamak plasma. We will present measurements from initial experiments with helium CTs of electron density n_e ≈ 5 × 10²¹ m^-3 and temperature T_e on the order of 10 eV injected into deuterium tokamak plasmas of electron density n_e ≈ 3 × 10¹⁸ m^-3 and temperature T_e ≈ 100 eV. Diagnostics used include passive ion Doppler spectroscopy, magnetic sensor arrays, a far-infrared (FIR) interferometer-polarimeter, and a high-speed camera. Passive ion Doppler spectroscopy is used to measure ion temperature of the CT using impurity lines. Electron density measurements are obtained from the FIR interferometer, while magnetic fluctuation activity is measured with in-vessel magnetic sensor arrays. A Phantom v710 camera is used to observe the injected CT plasma. MST can produce plasmas ranging from conventional q(a) > 2 tokamak, through ultra-low-q (0.25 < q(a) < 1), to reversed field pinch (RFP) configurations. This flexibility will allow reconnection ion heating to be investigated in plasmas of varying turbulence and mode activity. In future experiments, CT injection may be used to study turbulent reconnection in RFPs.