Diagnostics for a SPARC-like, high-field, compact, net-energy tokamak

Advances in high temperature superconductor (HTS) technology have opened a path to high field, compact fusion devices, like ARC [Sorbom 2015] and SPARC [Greenwald 2018]. The MQ1 tokamak [Mumgaard 2016] is a conceptual, compact HTS tokamak (R = 1.65 m) with magnetic field on axis B = 12 T and primary mission of achieving net energy. The high magnetic field, high density, and nuclear environment from high power DT operations (Q > 3) present both challenges and opportunities to diagnose MQ1, so diagnostics supporting its mission are explored. A neutronics suite (comprising micro-fission chambers, magnetic proton recoil spectrometers, and neutron cameras) is modeled in MCNP6 with a notional tokamak geometry as well as ne and Te profiles from TSC simulations. Expected neutron signals indicate that measurements of fusion power, ion temperature, deuterium-to-tritium fuel ratio, and self-heating profile are feasible. A combination interferometer-polarimeter, using one set of CO2 and HeNe lasers, is shown to measure line-averaged density for feedback control, poloidal magnetic field for constraining magnetic reconstructions, and fluctuations of both. Additional diagnostics assessed are magnetics, passive radiation detection, x-ray imaging crystal spectroscopy, and Thomson scattering.