Overview of the early campaign diagnostics for the SPARC tokamak (invited).

The SPARC tokamak is a high-field, Bt0 ∼12 T, medium-sized, R0 = 1.85 m, tokamak that is presently under construction in Devens, MA, led by Commonwealth Fusion Systems. It will be used to de-risk the high-field tokamak path to a fusion power plant and demonstrate the commercial viability of fusion energy.

Development of the neutral gas diagnostic system for neutral pressure measurements and gas analysis on the SPARC tokamak.

A suite of plasma diagnostics will be installed on the SPARC tokamak to allow for real-time plasma control, an investigation of high-field tokamak physics, and to de-risk the design of ARC, a compact fusion power plant with the aim to supply electricity to the grid. Among these diagnostics is the neutral gas diagnostics system (NTGS), a set of pressure sensors and gas analyzers used to monitor neutral pressure and gas composition for plasma control, optimization of wall conditioning, and helium ash removal, among other measurement functions linked to operational and scientific research needs. While reliable measurements of neutral pressure and gas composition have been fielded on existing magnetic-confinement fusion devices, SPARC represents a step increase in challenge due to its larger power density, higher field, high vacuum vessel bake temperatures, and higher neutron flux environment, as well as a step decrease in the accessibility for maintenance of in-vessel sensors.

Development of a bolometry diagnostic for SPARC.

To control and optimize the power of the SPARC tokamak, we require information on the total radiated power of the plasma and its 2D and 3D spatial distribution. The SPARC bolometry diagnostic is being designed and built to measure the radiated power for controlling power balance, investigating the dissipation capabilities of various divertor concepts, and measuring the efficacy of the disruption thermal load mitigation. Proven resistive bolometer sensor technology will be used, with 248 lines of sight integrated into pinhole cameras in 20 different locations.