Experimental observation of parametrically excited relaxation oscillations

Excitation of relaxation oscillations caused by the development of parametric instabilities in UHF-discharge plasma has been investigated experimentally. The instabilities occur in discrete narrow intervals of density because of the finite length of the plasma column. The experimental results are in satisfactory agreement with the theory of purely growing instability excitation. The observed parametric decay instabilities are due to local effects in the inhomogeneous layers at the ends of the column. (author)