Emission Intensity Enhancement of DC Arc Plasma Induced by External Oscillating Magnetic Field

Abstract

Key words DC arc plasma with aerosol supply, optical emission spectroscopy, plasma/magnetic field interaction. PACS 52.50.Dg Direct current (dc) arc plasma with continuous aerosol supply was coupled with an external oscillating magnetic field of a few tens of mT and a frequency of up to 1 kHz. Such configuration was used to alter the plasma-related radiative properties. The magnetic field was oriented perpendicularly to the electric field in the plasma and forced the arc column to oscillate as a whole with respect to the surrounding atmosphere. The magnitude of the applied magnetic field controls the amplitude of the oscillatory motion. Several parameters that can contribute to the radiative properties of the plasma were investigated (arc current, composition of aerosol introduced into the plasma, amplitude and frequency of the magnetic field applied). Spectral emission from different zones of the plasma column was measured by optical emission spectroscopy (OES). In comparison to steady-state plasma, the applied magnetic field induces an intensity enhancement of emission of the most analytes considered. The intensity enhancement is strongly affected by the amplitude and frequency of plasma column oscillations, i.e. by plasma column velocity. Also, intensity enhancement depends on the plasma zone observed.

Monochromatic imaging technique used to study dc arc plasma under the influence of a transverse magnetic field

“…The results presented in figure 7 are consistent with those described and explained previously [7,8]. In those papers, however, all the measurements were performed at axial positions of 1 and 8 mm and with different optical arrangements, with no data on intensity changes at other axial positions.…”

“…In that work, however, plasma was observed during longitudinal oscillations and at fixed lateral and axial positions. More recently, it was confirmed, with the same arc plasma source, that the emission intensity enhancement of various atoms and ions occurs mostly in distinctive plasma zones, but no explanation for such performance has been proposed [8].…”

Delayed responses of analyte emission in a pulse-modulated direct-current argon arc at atmospheric pressure

“…A preliminary investigation of the influence of easily ionized elements on the delayed responses of analyte spectral lines was also done [19]. We have recently published results concerning the possibility of improving analytical characteristics of this arc device, using the benefit of modulated plasma conditions that arise when an oscillating magnetic field is applied [20,21]. The aim of this work was to investigate delayed responses of analyte spectral lines that follow abrupt current change in order to get a better understanding of the processes that occur in the arc plasma, and also to investigate the possible use of power modulation to improve the analytical characteristics of the used arc device.…”