Description and properties of an r.f. plasma used for the study of parametric interaction of a strong E-M field with plasma

A type of r.f. discharge is described for which the resonant operating process gives an r.f. electric field in the plasma intense enough that the oscillation amplitude of the electron in that field is equal to or larger than the electron Debye length. This meets the conditions necessary to produce r.f. strong field instabilities, such as those predicted by Silin (1966). Moreover, the experimental set-up allows a precise measurement, in the strong field region, of the average electron frequency, f pe , and it is thus possible to know the ratio f pe /f 0 , (f 0 is the external r.f. field frequency) which plays an essential role in the study of electron parametric phenomena. Lastly, this plasma possesses an extremely low level of electron density fluctuation ( delta f pe /f pe approximately=10 -5 ) which enables one to study under the best of conditions the various instabilities resulting from electron parametric interaction. This plasma is self-sustained over the Dipolar resonance or the Tonks-Dattner resonances (also known as main and secondary resonances) and new data concerning operation on such resonances are being presented here, for example: pressure influence (collisions), dielectric permittivity and coupling factor.