Using integrated modeling to optimize fusion performance in MANTA, a negative triangularity fusion pilot plant concept*

Plasmas with negative triangularity (NT) can access high confinement and have power-handling characteristics desirable for a fusion pilot plant (FPP). In this work we use the transport solver TGYRO/TGLF to optimize the core operational space of MANTA: a high field, radiative, integrated NT FPP concept extending from the plasma core to the magnet structures [1]. MANTA is designed to have fusion power P_fus = 450 MW with a peak divertor heat flux of only 2.8 MW/m², a tritium breeding ratio of 1.15, and 90 MWe of net electricity with 40 MW of ICRF heating. MANTA utilizes high temperature superconducting magnets and a FliBe blanket, enabling mean magnet lifetimes of over 3110 MW-yrs, and has a projected overnight total cost of $3.4 billion. Informed by NT experiments, boundary conditions that lie between those of traditional L-mode and H-mode plasmas are employed to find multiple NT operating points with plasma fusion gain above 10 given various heating schemes. An NT FPP would not be constrained to maintain P_SOL above the L-H power threshold, allowing us to find the impurity fraction that maximizes P_fus for a given P_SOL < 50 MW.  Radial location scans of a Gaussian particle source reveal that density peaking scaling laws provide a serviceable lower bound on the expected density. The high-field MANTA approach is contextualized within a larger NT FPP operating space that includes high volume, high current scenarios as well as scans of aspect ratio and triangularity. Within this operating space, we adjudicate several distinct paths to an NT FPP that prioritize power-handling, with P_fus comparable to PT H-mode FPP concepts and low P_SOL that alleviates divertor integration challenges. This includes a larger, low field concept and a compact, high field concept both with P_fus > 400 MW while maintaining P_SOL < 50 MW.

[1] The MANTA Collaboration et al. “MANTA: A negative-triangularity NASEM-compliant fusion pilot plant", PPCF (under review)