[en] A plasma generator comprises a metallic tube of small diameter inside which can circulate a gas such as argon at a small flow rate, which is discharged at the front end of the tube. The tube is coupled with an energizing structure which can comprise a frequency generator supplying electromagnetic microwaves, via a coaxial connection, a coupling structure allowing the transfer of the energy of the generator to the front portion of the metallic tube. In the absence of a gas current in the tube, the front portion radiates the energy transmitted to it in the manner of an antenna. When a gas is discharged at the end of the tube, said energy allows maintaining a plasma in front of the latter. This plasma generator device is usable in many applications, such as a blowtorch a light source or torch usable in spectrography, a plasma motor or an ion source

[en] Experimental evidence of parametric excitation, by an intense external H.F. field, of an electron surface mode and an ion wave is presented. The pumping electromagnetic energy density is equal to or slightly larger than the thermal energy density of the electrons. The value of fsub(pe)/f₀ (electron plasma frequency/external field frequency) is that for an electron surface wave. Depending on the pressure and field intensity, this decay instability can lead to three types of low frequency oscillations, with frequencies close to the ion plasma frequency. Two of these are described by ALIEV and SILIN's intense field theory: one is the volume ion plasma oscillation and the other a surface ion plasma oscillation. The third corresponds to no known ion eigenmode. Several other features of the theory by ALIEV and co-workers are also confirmed experimentally, such as the harmonic excitation of the instability (nf₀ approximately fsub(pe)/√2, where n is an integer), the instability amplitude as a function of fsub(pe)/f₀ (above threshold conditions), the value of the mismatch parameter as a function of field strength and ion mass, and the existence of a fine structure corresponding to the symmetric and antisymmetric electron surface oscillations. Even at high pump field strengths, the decay products are nearly monochromatic i.e. the plasma does not become turbulent. (author)

[en] The case of a travelling surface wave sustaining a plasma column acting as the propagating medium is considered. The axial electron density distribution is investigated and the energy balance of the electron gas is established. The effective collision frequency for each experimental condition is determined

[en] In this report we investigate photon interferences in order to determine the wavelength distribution as a function of the position in the interference field.