H.F. INSTABILITIES IN THE HETEROGENEOUS PLASMA OF A PENNING DISCHARGE ION SOURCE WITH A HOLLOW CATHODE V.P. Gerasimov, S.A. Karev, V.A. Obukhov et G.G. Shishkin J. Phys. Colloques, 40 C7 (1979) C7-647-C7-648 DOI: 10.1051/jphyscol:19797314