Effect of iodine dissociation in an auxiliary discharge on gain in a pulser-sustainer discharge excited oxygen–iodine laser

Abstract

The paper presents the results of iodine vapour dissociation measurements in a high voltage, nanosecond pulse duration, repetitively pulsed discharge, used as an auxiliary (‘side’) discharge in an electric discharge excited oxygen–iodine laser. The side discharge, sustained in a high-pressure iodine vapour/helium mixture remained stable in the entire range of experimental conditions. Iodine dissociation fraction generated in the side discharge and measured in the laser cavity is up to 50%. However, the experiments showed that additional iodine dissociation generated in the side discharge only moderately increases laser gain, by 10–15%. Parametric gain optimization by varying main discharge pressure, O2 and NO fractions in the flow, I2 flow rate, pulsed discharge frequency and sustainer discharge power, with the side discharge in operation produces gain up to 0.08% cm−1. Two parameters that critically affect gain are the energy loading per molecule in the discharge and the NO flow rate controlling the O atom concentration in the flow. In particular, operation at the main discharge pressure of 60 Torr results in significantly higher gain than at 100 Torr, 0.080% cm−1 versus 0.043% cm−1, due to higher discharge energy loading per molecule at the lower pressure. Laser output power measured at the gain optimized conditions is 1.4 W.

Kinetics of Active Oxygen Species with Implications for Atmospheric Ozone Chemistry

“…The O 2 a 1 Δ‐X 3 Σ − (1.27 µm) and O 2 b 1 Σ ‐X 3 Σ − (0.76 µm) electronic transitions and the 10‐µm airglow emission from vibrationally excited ozone (designated by O 3 (υ) in the following) have been used to derive ozone densities in the atmosphere . Excited O 2 and O 3 molecules have an impact on atmospheric chemistry , and they are key species in the kinetics of chemical and energy transfer processes in oxygen‐containing plasmas .…”

Recent advances in the development of discharge‐pumped oxygen‐iodine lasers

“…Three different groups have investigated DOIL's that employ pulser-sustainer discharges [29,34,[45][46][47][48][49][50][51][52][53]. This approach permits the application of non-self sustained discharges with low ratios.…”

“…Predissociation of I or an alternative I atom donor using a discharge is a simpler approach, as it does not introduce chemical complications in the lasing medium [4,50,72,[78][79][80][81]. The primary challenge is to minimize I recombination during transport and injection.…”

Heterogeneous losses of externally generated I atoms for OIL

“…Electric-discharge [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and chemical [18][19][20] generators have been proposed as a source of iodine atoms for the use in OIL. Dissociation of iodine-containing molecules in electric-discharge plasmas had been proved to be useful for external production of iodine atoms.…”