Electron density fluctuations in a cylindrical magnetized plasma are investigated using a new simplified CO2 laser forward scattering technique. A He plasma with electron density and temperature of ne=4*1018 m-3 and Te=6 eV is confined in an axial magnetic field of B0=0.2 T. Scattering measurements perpendicular and parallel to the magnetic field have been made over several chords in one section of the plasma cylinder. Self-excited density fluctuations n(K, omega ) have been recorded in the parameter range of 3 cm-1<or=K<or=30 cm-1 and 20 kHz<or= omega /2 pi <or=500 kHz. Frequency spectra show maximum amplitude around nu pk approximately=60 kHz while the wave number maximum Kmax peaks at 4 cm-1. Wave number as well as frequency power spectra decay as K- alpha and f- beta with values for alpha and beta in the range between 4 and 6. Two different fluctuation modes, one quasicoherent and another fully turbulent, have been investigated. Striking similarities to turbulence measurements on Tokamaks could be observed.
Far-forward scattering of CO2-laser radiation by density fluctuations in a hollow cathode arc