Fluctuation-phase relation between positive and negative ions on pair-plasma electrostatic waves

摘要

Three kinds of electrostatic modes are experimentally observed to propagatealong magnetic-field lines for the first time in the pair-ion plasma consistingof only positive and negative fullerene ions with an equal mass. It is foundthat phase lags between the density fluctuations of positive and negative ionsvary from 0 to $\pi$ depending on the frequency and is fixed at $\pi$ in thecases of ion acoustic and ion plasma waves, respectively. In addition, a newmode with the phase lag about $\pi$ appears in an intermediate-frequency bandbetween the acoustic and plasma waves.