In this paper, an atmospheric pressure argon plasma plume generated by sinusoidal power input of moderate frequency (kHz range) and designed with dual-power electrodes is characterized and studied. Particularly, the effect of driving frequency in the 60–130 kHz range on the argon plasma discharge characteristics is investigated based on a detailed electrical and spectroscopic diagnostics. And, temporal and spatial optical emission spectroscopy is used to measure the plasma parameters, of which the excitation electron temperature is determined by the Boltzmann’s plot method whereas the electron density is estimated using the stark broadening of the hydrogen Balmer Hβ line. It is shown that at constant applied voltage and gas flow rate, the increase of driving frequency in the range of 60–100 kHz exerts no significant influences on discharge parameters. While once the driving frequency exceeds a certain value of about 100 kHz, the discharge becomes intense abruptly and the corresponding discharge parameters increase drastically with the driving frequency. Detailed analysis about the effect of driving frequency on discharge characteristics is presented and two different dominant electron loss mechanisms, namely transport-dominated loss and diffusion-dominated loss, are proposed to account for the distinct effects of the driving frequency on argon discharge characteristics.
Optical emission of the plasma generated on metal hydride target by pulsed laser beam from an Nd:YAG laser was used to investigate the temporal evolution of the line relative intensity, ion (electron) temperature (Te) and electron density (Ne). From relative emission intensities of the atomic and ionic species, the ion temperature using Saha- Boltzmann plots were evaluated. The electron density was determined utilizing the Stark broadening of the Hα-line at 656.27 nm. It was found that numerous lines of double-charged metal ion were visible only at the first 200 ns, and the single-charged metal ion reached the line intensity maximum. The relative intensities of ion line decrease with the increasing time, as opposite to atomic line became more intensive after 1 μs. The max electron density and ion temperature was between 400 ns and 600 ns, then ion temperature decreased from 1.3 eV down to 0.9 eV at the following 4 μs, but the electron density varied so irregularly that further investigation was required in furture.