Non-collisional Ion Heating and Magnetic Turbulence in the RFP

strong non-collisional ion heating occurs during sawtooth-like magnetic reconnection events in Madison Symmetric Torus, where ions are transiently heated to as high as 3 keV, often exceeding the electron temperature. The free energy source for this ion heating is the mean magnetic energy. Measured magnetic fluctuations exhibit an exponential spectral density consistent with dissipative nonlinear turbulent cascade, originating from unstable MHD tearing fluctuations, believed to be related to the observed non-collisional ion heating. Our key results are 1) achieved high ion temperature plasma through a non-collisional heating and then sustained by parallel current profile control helping to establish MST’s record energy confinement time of 12 ms, 2) the resulting ion heating has a square-root of the mass dependence where heavier ions heat up to higher temperature 3) the high frequency magnetic turbulence is anisotropic in wave number, most of the power is in the perpendicular wave number, and 4) we observe a dissipative cascade in