| Abstract: | Two wide spreaded methods for the measurement of plasma fluctuations are investigated both theoretically and experimentally. In limited regions of frequency and wave number, the fluctuation amplitudes obtained by probes and optical line radiation show sufficient good agreement; in general, however, different effects must be eliminated in order to obtain quantitative values. As an application, a transition from isothermal ion acoustic turbulence to a hybrid turbulent state including temperature fluctuations in a low pressure d.c. plasma has been discovered. |
