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Advancements in high temperature superconducting technology have opened apath toward high-field, compact fusion devices. This new parameter spaceintroduces both opportunities and challenges for diagnosis of the plasma. Thispaper presents a physics review of a neutron diagnostic suite for a SPARC-liketokamak [Greenwald et al 2018 doi:10.7910/DVN/OYYBNU]. A notional neutronicsmodel was constructed using plasma parameters from a conceptual device, calledthe MQ1 (Mission $Q \geq 1$) tokamak. The suite includes time-resolvedmicro-fission chamber (MFC) neutron flux monitors, energy-resolved radial andtangential magnetic proton recoil (MPR) neutron spectrometers, and a neutroncamera system (radial and off-vertical) for spatially-resolved measurements ofneutron emissivity. Geometries of the tokamak, neutron source, and diagnosticswere modeled in the Monte Carlo N-Particle transport code MCNP6 to simulateexpected signal and background levels of particle fluxes and energy spectra.From these, measurements of fusion power, neutron flux and fluence are feasibleby the MFCs, and the number of independent measurements required for 95%confidence of a fusion gain $Q \geq 1$ is assessed. The MPR spectrometer isfound to consistently overpredict the ion temperature and also have a1000$\times$ improved detection of alpha knock-on neutrons compared to previousexperiments. The deuterium-tritium fuel density ratio, however, is measurablein this setup only for trace levels of tritium, with an upper limit of $n_T/n_D\approx 6\%$, motivating further diagnostic exploration. Finally, modelingsuggests that in order to adequately measure the self-heating profile, theneutron camera system will require energy and pulse-shape discrimination tosuppress otherwise overwhelming fluxes of low energy neutrons and gammaradiation.  *Co-first-authorship

Neutron diagnostics for the physics of a high-field, compact, $Q\geq1$ tokamak