The presence of a beam in a toroidal plasma will affect the flow of impurity ions. By choosing an appropriate energy and direction of the beam, the impurity may be pumped out.
The high frequency electric field was applied to the mercury plasma produced in the glass tube perpendiculary to the longitudinal magnetic field. Avobe certain thresholds the high and the low frequency oscillations were excited when the applied r.f. frequency was near the lower hybrid resonance frequency. The matching condition of the frequency and the wavenumber was confirmed. The low frequency oscillation was identified to be the ion acoustic wave of (1, 1) mode.