Hydrogen Balmer beta: The separation between line peaks for plasma electron density diagnostics and self-absorption test. (March 2015)

• Record Type: Journal Article
• Authors: Ivković, Milivoje; Konjević, Nikola; Pavlović, Zoran
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 154(2015:Apr.)
• Page Start: 1
• Page End: 8
• Publication Date: 2015-03
• Subjects: Optical emission spectroscopy -- Stark broadening -- Hydrogen -- Plasma diagnostics -- Electron number density; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2014.11.014
• Languages: English
• ISSNs: 0022-4073

Abstract

Abstract: We propose a diagnostic technique for the measurement of plasma electron number density, N e, based on the wavelength separation between peaks, Δ λ PS, of hydrogen Balmer beta line, Hβ . In favor of the proposed diagnostic technique we demonstrate high sensitivity of Δ λ PS on N e and low sensitivity on plasma elementary processes and plasma parameters that may distort the line profile. These properties of Δ λ PS enable reliable N e plasma diagnostics in the presence of considerable self-absorption. On the basis of available theoretical data tables for the Hβ line profiles, simple N e = f (Δ λ PS ) formulas are proposed. Their validity is experimentally confirmed in a low initial pressure pulsed discharge for the N e range of (0.2–7)⁎10 23 m −3 . The agreement of the proposed formulas with another diagnostic technique is well within 10%. In addition, the difference in N e values obtained from peak separation and from the Hβ line width is successfully used as a self-absorption test for line profile. Highlights: Separation between peaks of Hβ line proposed for electron density diagnostics. Derived formulas for peak separations versus electron density. Formulas tested in high electron density low pressure pulsed arc. Applications of formulas in optically thick plasmas proven. Method for hydrogen Balmer beta line self-absorption testing proposed.