Linear gyrokinetic stability of a high β non-inductive spherical tokamak. (6th December 2021)

• Record Type: Journal Article
• Authors: Patel, B.S.; Dickinson, D.; Roach, C.M.; Wilson, H.R.
• Is Part Of: Nuclear fusion. Volume 62:Number 1(2022)
• Publication Date: 2021-12-06
• Subjects: gyrokinetics -- spherical tokamak -- electromagnetic -- turbulence -- kinetic ballooning mode -- micro tearing mode -- high β; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ac359c
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Spherical tokamaks (STs) have been shown to possess properties desirable for a fusion power plant such as achieving high plasma β and having increased vertical stability. To understand the confinement properties that might be expected in the conceptual design for a high β ST fusion reactor, a 1 GW ST plasma equilibrium was analysed using local linear gyrokinetics to determine the type of micro-instabilities that arise. Kinetic ballooning modes and micro-tearing modes are found to be the dominant instabilities. The parametric dependence of these linear modes was determined and, from the insights gained, the equilibrium was tuned to find a regime marginally stable to all micro-instabilities at θ 0 = 0.0. This work identifies the most important micro-instabilities expected to generate turbulent transport in high β STs. The impact of such modes must be faithfully captured in first-principles-based reduced models of anomalous transport that are needed for predictive simulations.