The SMall Aspect Ratio Tokamak - SMART

Spherical tokamaks (STs) [1,2] constitute an attractive path to a fusion reactor or volumetric neutron source due to their high-power densities at relatively modest costs and dimensions. The high-power densities achievable in STs pose, however, even more severe constraints on their plasma facing components (PFCs) than those observed in conventional tokamaks. Alternative power and particle exhaust techniques are, thus, mandatory for a ST-based fusion power plant (FPP) [3].

Recent experiments at the TCV and DIII-D conventional tokamaks have shown that Negative Triangularity (NT) shaped L-mode plasmas can feature H-mode like confinement factors with attractive power exhaust properties [4]–[10]. Interestingly, in conventional tokamaks, NT shaped L-mode plasmas show H-mode like confinement factors with:

  • Enhanced core thermal plasma confinement
  • No edge pedestal and thus, no edge localised modes (ELMs)
  • Broadening of escaping power and particle channel, i.e. wider exhaust footprint and reduced peak power on PFCs
  • Divertor naturally placed at larger radii
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Mission

The SMall Aspect Ratio Tokamak (SMART), with R=0.4m, a=0.2m, Ip=500 kA, Bt<1T, pulse lengths up to 500 ms and neutral beam injection power of 1MW [11], aims at exploring high confinement NT-shaped plasmas in low aspect ratio tokamaks. The unique SMART plasma shaping capabilities makes this experiment a first-of-a-kind that will certainly break new ground on the road to a ST-based FPP [12]–[14].

To achieve this, the Plasma Science and Fusion Technology (PSFT) team of the University of Seville operates the SMART tokamak with the following goals:

  • High confinement regimes in negative and positive triangularity plasmas. A first-of-a-kind in STs.
  • Energetic particles and magnetohydrodynamic (MHD) stability.
  • Edge physics and plasma wall interaction.
  • Innovative power exhaust techniques.
  • Advanced real time control techniques.
  • Training of fusion engineers and physicists.
  • Contribute to key scientific and technological challenges towards a fusion
    power plant.
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