Speaker: Prof. Hiroyuki Yamaguchi, National Institute for Fusion Studies
Abstract: As a candidate for the post-Large Helical Device at National Institute for Fusion Science (NIFS), Japan, our research group has been designing a new stellarator-type experiment device, Variable Symmetry Torus (VAST). To study the effect of particle motion on the collective phenomena in plasma, such as micro-turbulences, magnetic flexibility is emphasized in designing VAST: both quasi-axisymmetric (QA) and quasi-isodynamic (QI)-like magnetic configurations can be realized in a single device. With the basic design for modular and auxiliary coils being almost fixed, the physics design of VAST has made substantial progress in the last year. Both QA and QI-like modes have been confirmed to have finite-beta MHD equilibria with good magnetic surfaces. Gyrokinetic simulations have shown clear differences in ion-temperature-gradient driven turbulence and associated zonal flows between these configurations. Recent attempts to predict plasma performances and heating scenarios by integrated simulation will also be presented.