Oxygen assisted iodine atoms production in an RF discharge for a cw oxygen-iodine laser

Influence of molecular oxygen on iodine atoms production in an RF discharge

“…In mixtures with Ar, at 200 W discharge power input, corresp onding to a power density of 6.5 W cm −3 , an addition of 0.1 mmol s −1 O 2 had a profound effect, increasing [I] up to 25% and leading to almost 100% extraction of iodine from CH 3 I. A further increase in discharge power up to 300 W had almost no effect for mixtures with oxygen, because complete iodine extraction had already occurred at 200 W. For mixtures without oxygen at 300 W larger [I] were observed at large CH 3 I flow rates, but a fraction of discharge power spent on iodine extraction-η was smaller than at 200 W, where it amounted to 16% [14]. η was calculated as the ratio between the power needed to break the CH 3 -I bonds (bond strength-234 kJ mol −1 ), obtained as the product of the bond strength and iodine atoms flow rate at the discharge output, and the discharge power.…”

“…About 80% of iodine contained in CH 3 I was extracted at small flow rates and 40% at large flow rates. More detailed analysis of the experiments with Ar has been published in [14].…”

“…The photographs of the discharge reproduced from [14] in figure 2 illustrate the change in chemical composition of the gas mixture along the flow which at a small CH 3 I flow rate revealed itself as a change of color along the plasma column. At a larger CH 3 I flow rate all the discharge became bluish-violet in color and its size along the flow decreased.…”

“…Although active resistance of the matching circuit at 40 MHz was estimated to be less than 0.1 Ω, for further analysis it was assumed that a 10% loss was present between the power meter and the discharge. A more detailed description of the discharge setup was published in [14].…”

“…A similar model was described briefly in [11,14], where the influence of oxygen addition to Ar : He : CH 2 , where D-diffusion coefficient, r-tube radius) for I, O atoms and CH 3 radicals in Ar mixtures were equal to ~300, 800 and 630 s −1 , and in He-900, 1600 and 1400 s −1 , correspondingly. The probability of surface recombination for I atoms, CH 3 and O was chosen to be 1, although there are indications that on a clean surface for I atoms it might be considerably smaller [46] down to 10 −3 ÷ 10 −4 .…”