Projections of H-mode access and edge pedestal in the SPARC tokamak. (October 2020)

• Record Type: Journal Article
• Authors: Hughes, J. W.; Howard, N. T.; Rodriguez-Fernandez, P.; Creely, A. J.; Kuang, A. Q.; Snyder, P. B.; Wilks, T. M.; Sweeney, R.; Greenwald, M.
• Is Part Of: Journal of plasma physics. Volume 86:Number 5(2020)
• Publication Date: 2020-10
• Subjects: fusion plasma, -- plasma confinement; Plasma (Ionized gases) -- Periodicals; 530.4405
• DOI: 10.1017/S0022377820001300
• Languages: English
• ISSNs: 0022-3778

Abstract

Abstract : In order to inform core performance projections and divertor design, the baseline SPARC tokamak plasma discharge is evaluated for its expected H-mode access, pedestal pressure and edge-localized mode (ELM) characteristics. A clear window for H-mode access is predicted for full field DT plasmas, with the available 25 MW of design auxiliary power. Additional alpha heating is likely needed for H-mode sustainment. Pressure pedestal predictions in the developed H-mode are surveyed using the EPED model. The projected SPARC pedestal would be limited dominantly by peeling modes and may achieve pressures in excess of 0.3 MPa at a density of approximately 3 × 10 20 m −3 . High pedestal pressure is partially enabled by strong equilibrium shaping, which has been increased as part of recent design iterations. Edge-localized modes (ELMs) with >1 MJ of energy are projected, and approaches for reducing the ELM size, and thus the peak energy fluence to divertor surfaces, are under consideration. The high pedestal predicted for SPARC provides ample margin to satisfy its high fusion gain ( Q ) mission, so that even if ELM mitigation techniques result in a 2× reduction of the pedestal pressure, Q > 2 is still predicted.