Overview of the early campaign diagnostics for the SPARC tokamak is the invited 2024 Review of Scientific Instruments paper in which 📝Matt Reinke and 86 co-authors describe the roughly fifty instruments that will measure 📝SPARC — the apparatus by which its claims become checkable.
Buried in a diagnostics paper is the clearest public statement of SPARC's operating plan. The first campaign targets a fusion gain above 1 with fewer than 10 megawatts of 📝ion cyclotron resonance heating, at a high 📝plasma current near 8.5 megaamps, in 📝L-mode fueled by 📝D-T gas injection. The second campaign turns to 📝H-mode in 📝D-D. Reaching net gain in the lower-confinement regime first is a deliberately conservative order of operations.
The engineering difficulty is not novelty but conditions and pace. Nearly every technique here is established — 📝Thomson scattering, 📝interferometry, 📝spectroscopy, 📝neutron diagnostics. What is unprecedented for a medium-sized 📝tokamak is deploying them all at once into an environment this thermally, electromagnetically and radiologically hostile, on a schedule set by first plasma. The paper is an overview with system-specific companion publications beneath it — collected in 📝The SPARC Diagnostics Papers — which makes it the correct entry point into how SPARC will be observed.
A result nobody can check is not a result. These fifty instruments are how we intend to make SPARC's performance arguable by people who do not work here.