The energy confinement time of net current-free plasmas in the Large Helical Device (LHD) is comparable to ELMy H-mode with q = 4.5 on the scale of IPB98(y,2). Broad temperature with high edge pressure, which is of robust nature in LHD, recalls the pedestal structure in tokamak H-mode. Basic parameter dependence is, however, weak gyro-Bohm in both edge and core regions. This suggests that one physical model could explain the observed profile. The edge temperature is proportional to the square root of heating power and inversely proportional to the square root of edge density. This means that edge pressure and its gradient are not limited and can be increased by heating power.
Edge localized modes and edge pedestal in NBI and ICRF heated H, D and T plasmas in JET