Impurity Modes and Signature of the I-Regime

The excitation of an impurity 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 ``knee'' at the edge but no density ``knee'' 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. {\bf 17}, 377 (1966).\\[0pt] [2] B. Coppi and T. Zhou, Phys. Lett. A {\bf 375}, 2916 (2011); PoP {\bf 18} (2011)(in press) and MIT-LNS Report HEP 09/04 (2009).\\[0pt] [3] A. Hubbard, et al., PoP {\bf 18}, 056115 (2011).\\[0pt] [4] I. Cziegler(2010).[5]B. Coppi, Nucl. Fusion {\bf 42}, 1 (2002).