Core-Pedestal Plasma Configurations in Advanced Tokamaks

Several configurations for the core and pedestal plasma are examined for a predefined tokamak design by implementing multiple heating/current drive (H/CD) sources to achieve an optimum configuration of high fusion power in a noninductive operation while maintaining an ideally magnetohydrodynamic (MHD) stable core plasma using the IPS-FASTRAN framework. IPS-FASTRAN is a component-based lightweight coupled simulation framework that is used to simulate magnetically confined plasma by integrating a set of high-fidelity codes to construct the plasma equilibrium (EFIT, TOQ, and CHEASE), calculate the turbulent heat and particle transport fluxes (TGLF), model various H/CD systems (TORIC, TORAY, GENRAY, and NUBEAM), model the pedestal pressure and width (EPED), and estimate the ideal MHD stability (DCON). The TGLF core transport model and EPED pedestal model are used to self-consistently predict plasma profiles consistent with ideal MHD stability and H/CD (and bootstrap) current sources. In order to evaluate the achievable and sustainable plasma beta, varying configurations are produced ranging from the no-wall stability to with-wall stability regimes, simultaneously subject to the self-consistent TGLF, EPED, and H/CD source profile predictions that optimize configuration performance. The pedestal density, plasma current, and total injected power are scanned to explore their impact on the target plasma configuration, fusion power, and confinement quality. A set of fully noninductive scenarios are achieved by employing ion-cyclotron, neutral beam injection, helicon, and lower-hybrid H/CDs to provide a broad profile for the total current drive in the core region for a predefined tokamak design. These noninductive scenarios are characterized by high fusion gain (Q similar to 4) and power (P-fus similar to 600 MW), optimum confinement quality (H-98 similar to 1.1), and high bootstrap current fraction (f(BS) similar to 0.7) for Greenwald fraction below unity. The broad current profile configurations identified are stable to low-n kink modes either because the normalized pressure beta(N) is below the no-wall limit or a wall is present.

Automated summary

This study examines different configurations for the core and pedestal plasma of a predefined tokamak design utilizing multiple heating/current drive sources to achieve high fusion power and maintain ideal MHD stability. The IPS-FASTRAN framework is used to simulate the plasma equilibrium, turbulent transport fluxes, H/CD systems, pedestal pressure and width, and ideal MHD stability. Various configurations are produced and evaluated for their impact on plasma configuration, fusion power, and confinement quality. Fully noninductive scenarios are achieved with high fusion gain and power, optimal confinement quality, and high bootstrap current fraction.