Time of flight studies of propagating electrostatic longitudinal waves in an homogeneous plasma

Abstract

Describes an experimental measurement of the time of flight of a high frequency electrostatic longitudinal sine wave burst through a hot, homogeneous and isotropic plasma. The group velocity of the pulse was measured with a good accuracy for frequencies higher than 1.2 times the plasma frequency (fp). For frequencies between fp and 1.2 fp (in this range the plasma is a high dispersive medium), and for small distances of propagation, up to 2 wavelengths the pulse maximum travels with a velocity lower than the group velocity, in good agreement with numerical calculation. For larger distances of propagation, the sine wave burst splits into 2 pulses: the first pulse seems to be due to the propagation of electron-ballistic waves, while the second one is characteristic of the principal Landau poles.