Abstract
The SMall Aspect Ratio Tokamak (SMART) device is a new compact (plasma major radius Rgeo≥0.40 m, minor radius a≥0.20 m, aspect ratio A≥1.7) spherical tokamak, currently in development at the University of Seville. The SMART device has been designed to achieve a magnetic field at the plasma center of up to Bϕ=1.0 T with plasma currents up to Ip=500 kA and a pulse length up to τft=500 ms. A wide range of plasma shaping configurations are envisaged, including triangularities between −0.50≤δ≤0.50 and elongations of κ≤2.25. Control of plasma shaping is achieved through four axially variable poloidal field coils (PF), and four fixed divertor (Div) coils, nominally allowing operation in lower-single null, upper-single null and double-null configurations. This work examines phase 2 of the SMART device, presenting a baseline reference equilibrium and two highly-shaped triangular equilibria. The relevant PF and Div coil current waveforms are also presented. Equilibria are obtained via an axisymmetric Grad-Shafranov force balance solver (Fiesta), in combination with a circuit equation rigid current displacement model (RZIp) to obtain time-resolved vessel and plasma currents.
Highlights
Spherical tokamaks (ST) are a sub-class of magnetic fusion devices notable for their narrow radial extent, reduced aspect ratios, and represent a promising economic path to commercial fusion due to their compact form, cost-effectiveness and high power density [1,2,3]
This paper presents an outline of the SMall Aspect Ratio Tokamak (SMART) device and key target parameters of developmental phases 1–3, before focusing on the modelling of three high-shaped equilibria, including an analysis of the breakdown thresholds and associated coil current waveforms for each scenario
This work focuses on SMART phase 2 and addresses the start-up procedure, plasma breakdown criteria and degree of achievable plasma shaping
Summary
Spherical tokamaks (ST) are a sub-class of magnetic fusion devices notable for their narrow radial extent, reduced aspect ratios, and represent a promising economic path to commercial fusion due to their compact form, cost-effectiveness and high power density [1,2,3]. The aggregated findings from these, and other ST devices have shown encouraging re sults including; high bootstrap current fractions [1,5], enhanced sta bility to pressure driven instabilities [2] and reduced particle-driven instabilities [27] as compared to traditional high-aspect ratio designs. These benefits are typically attributed to an enhanced plasma-β, and are thought to arise from strong toroidal flow and flow shear present in such low aspect ratio plasmas [28,29].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
