Universal instability in a potassium plasma

We have discovered oscillations in a highly ionized potassium plasma of non-uniform density in a magnetic field of an intensity of 600–1600 Oe and observed three or four harmonics with a fundamental frequency of ∼5–10kHz. The oscillations represent an azimuthal wave having a component along the magnetic field. Oscillation frequency is inversely proportional to the magnetic field strength. Oscillations are observed both in a dilute ( n = 10 8 –10 9 cm –3 ), and in a dense plasma ( n = 10 10 –5 × 10 11 cm –3 ). Oscillation excitation is not related to the presence of electric layers on the plasma boundary. It is shown that the observed oscillations are the development of "universal" instability of a plasma of non-uniform density.