No abstract

ion minority mncentrations in a w e d y ionized hydrogen plasma are determined through the comparison between the measured wavelength of the neutralized ion Bernstein waves and the theoretical one, given by the solution of the complete electrostatic dispersion relation. A simple model based on the resolution of fluid balance equations permits us to explain the presence of a high percentage of H:The presence of ion impurities' in weakly ionized plasmas is important for explaining the results of various nonlinear plasma-wave experiments, such as parametric decay (Ono et a1 1980) and soliton propagation (Pierre ef a1 1985).

This article describes the use of Langmuir probes to measure plasma parameters in low density, low temperature plasmas with a strong applied magnetic field. The experiment has been performed at the Physics Department of Milan’s University on the steady-state toroidal machine “Thorello.” Results have been analyzed by taking into account instrumental and ionic sheath effects. Finally, experimental results have been compared with direct measurements of the electron distribution function in Thorello.

No abstract

AbStiiCt-Elect~ostatic wave propagation transverse to a magnetic field B is analyzed in the range of the ion cyclotron frequency in a toroidal device. The clmtrostatic ion cyclotron waves are excited by means of an electromagnetic signal injected through an antenna system located in the centre of the plasma. For the first time the backward mode is detected in hydrogen and deuterium plasmas. A comparison between the theoretical dispersion relation and the experimental results permits an indirect accurate estimate of the ion temperature, typically in the range 0.054.3 eV.