Modified Fowler–Milne method for the spectroscopic determination of thermal plasma temperature without the measurement of continuum radiation

Abstract

A technique based on the Fowler-Milne method for the spectroscopic determination of thermal plasma temperatures without measuring continuum radiation is presented. This technique avoids the influence of continuum radiation with the combined line and continuum emission coefficients to derive the plasma temperatures. The amount of continuum emission coefficient is estimated by using an expression related to the Biberman factors. Parameters that affect the accuracy of the proposed technique and errors in the measured plasma temperatures are analyzed. It is shown that, by using the Ar I 696.5 nm line with a bandwidth of 3.27 nm without taking into account the continuum radiation, the plasma temperature measured will be lower on the order of up to 1000-3000 K for temperatures from 20,000 to 24,000 K. The theoretically predicted temperature errors are in good agreement with the experimental results, indicating that the proposed technique is reliable for plasma temperature measurement.

Shielding‐gas‐controlled atmospheric pressure plasma jets: Optical emission, reactive oxygen species, and the effect on cancer cells

“…The intensity of the continuum radiation depends linearly on the electron, ion, and neutral densities and is also a function of the emission wavelength, electron temperature, momentum transfer cross section (for electron‐neutral), and correction factors (for electron‐ion, called Biberman factors) . It has been reported for argon APPJs that, due to low ionization fractions, scattering with neutrals produces the majority of the emission, whereas for hot thermal argon plasmas, the interaction with ions is more important …”

Temperature measurement of asymmetrical pulsed TIG arc plasma by multidirectional monochromatic imaging method

“…However, we neglected this effect mainly due to the experimental complexity. It has been estimated by S. Ma et al that the effect of continuum radiation is at most 500 K for temperatures below 17,000 K and 1000 K for 20,000 K [19]. Although this study neglected the effect of continuum radiation, the effect in our experiment must be smaller than that in their experiment, because the FWHM of their filter is 3.24 nm which is wider than ours.…”

Pulsed arc light monitoring and temperature reconstruction with arc welding

“…The novel method was proposed to predict arc light noise in order to develop the accuracy of arc vision [13]. Narrow band filters (with 696.5 and 794.8 nm) were usually used for Ar-I monitoring when the welding arc temperature distributions were studied with Fowler-Milne [14][15][16]. The different arc light energy distribution could also reflect the typical charged particles and certain charged status [17].…”