EXPERIMENTAL STUDIES OF MULTIMODE HELICON PLASMA-WAVES

Helicon waves were excited by a Nagoya type III antenna in a steady st ate argon magnetized plasma column with Dc magnetic field B-o = 400-50 0 G, electron density 10(12)-10(13) cm(-3) and neutral species pressur e about 20 mTorr. Wavelength measurements made with B-dot probes at th e edge of the plasma column show the presence of multimode standing he licon waves. Azimuthal mode numbers m = +1, 0 and -1 were detected wit h m = +1 dominant. Radial density profiles were measured with Langmuir probes. The wavelength measurements are shown to agree with theoretic al calculations of helicon waves in radially non-uniform plasma.