Heavy Particle Modes and I-mode Plasmas

The excitation of a heavy particle mode [1,2] at the plasma edge is considered as the signature of the I-Regime [3]. The mode phase velocity, predicted in the electron diamagnetic velocity direction, was confirmed by the experiments [4]. The outward impurity transport produced by this mode is consistent with the observation that impurities accumulate at the edge in the I-Regime, a feature not present in the EDA or Elmy H-Regime. The plasma spontaneous rotation in the ion diamagnetic velocity direction is also consistent with the mode phase velocity direction, according to the Accretion Theory [5] of this phenomenon. In accordance with our theory, the I-Regime exhibits a temperature pedestal at the edge but no density pedestal as the mode excitation involves large values of $d\ln T_i/d\ln n_i$. A correlation of the values of the observed poloidal magnetic field fluctuations with those of the derived density fluctuations is provided by the same theory.\\[4pt] [1] B. Coppi et al., Phys. Rev. Lett. 17, 377 (1966).\\[0pt] [2] B. Coppi and T. Zhou, Phys. Lett. A 375, 2916 (2011); PoP 19, 012302 (2012).\\[0pt] [3] A. Hubbard et al., PoP 18, 056115 (2011).\\[0pt] [4] I. Cziegler (2010).\\[0pt] [5] B. Coppi, Nucl. Fusion 42, 1 (2002).