Quantitative measurement of atomic hydrogen in low-pressure methane flames using two-photon LIF calibrated by krypton

Evaluation of LIF thermometry technique using Krypton as a tracer: Impact of laser lineshape and collisional bandwidth

“…It is to be noted that the density of Kr in a helicon plasma was previously determined by TPLIF [15]. Among the possible Kr transitions from the ground state, we propose the 5p ' 1 D2 (2×204 nm) to take advantage of the proximity to the H-atom line for further detection by TPLIF [16,17] Hence the objective of this work is to evaluate the performance of TPLIF thermometry based on Kr density by analyzing both the effect of laser lineshape and collisional bandwidth. The first aspect was achieved by using a ns-laser (0.2 cm -1 FWHM) and a femtosecond (fs) laser (bandwidth of approx.…”

“…Details about the burners and the gas supply are given in Ref. [17,4,19] for B1, B2, and B3, respectively. At low pressure, three flames were selected (F1, F2, F3) because the temperature profiles as a function of height-above-the-burner (HAB) have previously been measured using LIF thermometry (OH or NO) [20][21][22] and will serve as reference T profiles.…”

“…The laser bandwidth of the doubled dye laser output was determined to be 0.16 cm −1 at 305 nm from previous work, and the 204.13-nm bandwidth is estimated to be around 0.15-0.2 cm −1 . The experimental set-up is identical to the one described in [17], except that a fast photomultiplier tube (PMT) (Hamamatsu, H11625-20-NF, 0.5 ns rise time) was used. Each measurement represents an accumulation of 600 laser shots, and profiles along HAB or radial distance (r) were repeated at least three times.…”

“…According to Refs [17,23], the time-integrated TPLIF signal of Kr, SKr, that is T-dependent, can be expressed as a function of the Kr density [Kr] as follows:…”

“…The LIF decay rate is extracted using a deconvolution method described in [17]. Rayleigh scattering signal at 615 nm was measured with the PMT used during this work.…”