RESONANT DAMPING OF HELICON WAVES IN POTASSIUM

A comprehensive experimental study of resonant or collisionless damping of helicon waves has been performed in high-purity potassium. Four different resonant damping effects were studied: cyclotron damping, Landau damping, giant quantum oscillations in the Landau damping, and damping due to helicon-acoustic-wave interaction. All effects were studied under stronger nonlocal conditions than in previous work by employing specimens having electron mean free paths of 0.3 mm and utilizing experimental frequencies up to 170 MHz. An abrupt cyclotron damping edge and giant quantum oscillations were observed for the first time. The observations are in close agreement with predictions based on the free-electron model. © 1969 The American Physical Society.