Novel xenon calibration scheme for two-photon absorption laser induced fluorescence of hydrogen

Abstract

Two photon absorption laser induced fluorescence (TALIF) measurements of neutral hydrogen and its isotopes are typically calibrated by performing TALIF measurements on krypton with the same diagnostic system and using the known ratio of the absorption cross sections [K. Niemi et al., J. Phys. D 34, 2330 (2001)]. Here we present the measurements of a new calibration method based on a ground state xenon scheme for which the fluorescent emission wavelength is nearly identical to that of hydrogen, thereby eliminating chromatic effects in the collection optics and simplifying detector calibration. We determine that the ratio of the TALIF cross sections of xenon and hydrogen is 0.024 ± 0.001.

Two-photon LIF on the HIT-SI3 experiment: Absolute density and temperature measurements of deuterium neutrals

“…A calibration scheme employing a xenon transition solves this and is described in another manuscript in this issue. 12…”

“…The widths of Kr spectra were anomalously wide due to isotopic broadening, as reported by Magee, so the widths of those velocity distributions do not correspond to the temperature of the neutral gas. 12 For each measurement location, a new Kr calibration was performed. The signal-to-noise ratio (SNR) of the Kr measurements were excellent.…”

Two Photon Absorption Laser Induced Fluorescence for Fusion Class Plasmas

“…This absorption spectrum, generated by the TALIF diagnostic, was used to measure the velocity distribution of hydrogen isotope neutrals with high spatial and temporal resolution [34]. By performing a TALIF measurement with the same laser on a known density of a calibration gas, absolute calibration of the density can be derived through these measurements [30], [31], [35].…”

“…The temperatures drop by a factor of two, and the spectra are plotted using the UV wavelengths rather than the fundamental dye wavelengths to coincide with the conventions used in previous WVU TALIF works [31], [60], [66]. The method for temperature calculation is described in section 2.4, and corresponds to a one dimensional velocity distribution which is proportional to nm [35].…”

“…For krypton and hydrogen, the relative absorption cross section has been reported in the literature[30]. For xenon and hydrogen, the relative absorption cross section was recently determined at WVU[35]. The absorption cross section is the same for both hydrogen and deuterium.Each term in Equation (3.2) marked with an "H" is related to hydrogen and each term related to the calibration gas is marked with a "C." Sx terms refer to the integrated signal from Equation (3.1) and nx terms refer to density from Equation (3.1).…”