Laser-Induced Plasma Spectroscopy of Hydrogen Balmer Series in Laboratory Air

Abstract

Stark-broadened emission profiles for the hydrogen alpha and beta Balmer series lines in plasma are measured to characterize electron density and temperature. Plasma is generated using a typical laser-induced breakdown spectroscopy (LIBS) arrangement that employs a focused Q-switched neodymium-doped yttrium aluminum garnet (Nd : YAG) laser, operating at the fundamental wavelength of 1064 nm. The temporal evolution of the hydrogen Balmer series lines is explored using LIBS. Spectra from the plasma are measured following laser-induced optical breakdown in laboratory air. The electron density is primarily inferred from the Stark-broadened experimental data collected at various time delays. Due to the presence of nitrogen and oxygen in air, the hydrogen alpha and beta lines become clearly discernible from background radiation for time delays of 0.4 and 1.4 μs, respectively.

Electron Density from Balmer Series Hydrogen Lines and Ionization Temperatures in Inductively Coupled Argon Plasma Supplied by Aerosol and Volatile Species

“…For helium atmospheric pressure microwave induced plasma, the similar values of the electron density were obtained from the H and H lines [28]. Recently, many works are devoted to determination of from various hydrogen lines in laser-induced plasma [27,[30][31][32] due to very dynamic expansion and applications of such plasma. Pardini et al [27] evaluated the plasma electron density through the measurements of the Stark broadening of the first-five members of the hydrogen Balmer series and compared experimental results with the predictions of three theories that described laser-induced breakdown plasma.…”

“…In the last years, attention has been paid to the use of other than H hydrogen lines for the electron density determination [19,[22][23][24][25][26][27][28][29][30][31][32] in various plasma. Konjević et al [23] discussed difficulties appearing during experimental line profile analysis for higher members of Balmer series and compared theory versus experiments for low plasma diagnostics.…”