@article{oai:repo.qst.go.jp:00082718,
 author = {Beeke, Oliver and Barnes, Michael and Romanelli, Michele and Nakata, Motoki and Maiko, Yoshida and Maiko, Yoshida},
 issue = {6},
 journal = {Nuclear Fusion},
 month = {Apr},
 note = {We have used the local-δf gyrokinetic code GS2 to perform studies of the effect of flux-surface shaping on two highly-shaped, low- and high-β JT-60SA-relevant equilibria, including a successful benchmark with the GKV code. We find that for a high-performance plasma, i.e. one with high plasma beta and steep pressure gradients, the turbulent outwards radial fluxes may be reduced by minimizing the elongation. We explain the results as a competition between the local magnetic shear and finite-Larmor-radius (FLR) stabilization. Electromagnetic studies indicate that kinetic ballooning modes are stabilized by increased shaping due to an increased sensitivity to FLR effects, relative to the ion-temperature-gradient instability. Nevertheless, at high enough β, increased elongation degrades the local magnetic shear stabilization that enables access to the region of ballooning second-stability.},
 title = {Impact of shaping on microstability in high-performance tokamak plasmas},
 volume = {61},
 year = {2021}
}