Overview of the SPARC tokamak

TLDR

The SPARC tokamak is a critical next step toward commercial fusion energy, continuing the high‑field Alcator path with rare‑earth barium copper oxide superconducting magnets to achieve high performance in a compact device. SPARC is designed as a high‑field, compact superconducting D‑T tokamak to achieve fusion gain Q > 2, and this work presents its role in the path to commercial fusion, its parameters, current design status, and the basis for performance projections. SPARC employs a 12.2 T, 1.85 m major‑radius, 0.57 m minor‑radius superconducting D‑T tokamak using rare‑earth barium copper oxide HTS magnets, with conservative physics assumptions (H98,y2 = 0.7) projecting Q≈11 and 140 MW fusion power. With conservative assumptions Q > 2 is achievable, and with nominal assumptions Q≈11 and 140 MW fusion power are projected, making SPARC a unique platform for burning‑plasma physics with high density, temperature, and power density relevant.

Abstract

The SPARC tokamak is a critical next step towards commercial fusion energy. SPARC is designed as a high-field ( $B_0 = 12.2$ T), compact ( $R_0 = 1.85$ m, $a = 0.57$ m), superconducting, D-T tokamak with the goal of producing fusion gain $Q>2$ from a magnetically confined fusion plasma for the first time. Currently under design, SPARC will continue the high-field path of the Alcator series of tokamaks, utilizing new magnets based on rare earth barium copper oxide high-temperature superconductors to achieve high performance in a compact device. The goal of $Q>2$ is achievable with conservative physics assumptions ( $H_{98,y2} = 0.7$ ) and, with the nominal assumption of $H_{98,y2} = 1$ , SPARC is projected to attain $Q \approx 11$ and $P_{\textrm {fusion}} \approx 140$ MW. SPARC will therefore constitute a unique platform for burning plasma physics research with high density ( $\langle n_{e} \rangle \approx 3 \times 10^{20}\ \textrm {m}^{-3}$ ), high temperature ( $\langle T_e \rangle \approx 7$ keV) and high power density ( $P_{\textrm {fusion}}/V_{\textrm {plasma}} \approx 7\ \textrm {MW}\,\textrm {m}^{-3}$ ) relevant to fusion power plants. SPARC's place in the path to commercial fusion energy, its parameters and the current status of SPARC design work are presented. This work also describes the basis for global performance projections and summarizes some of the physics analysis that is presented in greater detail in the companion articles of this collection.