Parametric study of a highly efficient chemical oxygen-iodine laser with supersonic mixing of iodine and oxygen

Abstract

We report on a detailed parametric study of the extremely efficient supersonic chemical oxygen-iodine laser recently developed in our laboratory [V. Rybalkin, A. Katz, B. D. Barmashenko, and S. Rosenwaks, Appl. Phys. Lett. 85, 5851 (2004)]. At the early stage of operation, 40.0% efficiency was measured for 1 s followed by a sustained 35.5% chemical efficiency for 20 s. The power and spatial distributions of the gain and temperature across the flow were measured for different supersonic nozzles with both staggered and nonstaggered iodine injection holes, different injection locations along the flow and nozzle throat heights. The effects of the partial pressure of O2 and the residence time of the flow in the generator, as well as the heating of the nozzle, are discussed and shown to be crucial in attaining this high efficiency. By carefully studying and optimizing the operation of the chemical generator, 0.73 yield of singlet oxygen was obtained for conditions corresponding to the highest efficiency.

Comparing modeling and measurements of the output power in chemical oxygen-iodine lasers: A stringent test of I2 dissociation mechanisms

“…Since the distance between the mirrors in Ref. 19 is about four times larger than in our experiments 14 we assume that our diffraction losses are about two times smaller than in Ref. 19.…”

“…For the first nozzle a record-breaking ϳ40% efficiency was measured which is the highest reported chemical efficiency of any supersonic COIL; 2,14 for the second nozzle also a rather high, ϳ38% efficiency was achieved. 14 The high pressure supersonic ejector COIL 15,17 uses a special nozzle bank ͑one section is shown in Fig. 2͒ where a transonic O 2 ͑a͒ / O 2 ͑X͒ flow of the Mach number M = 1 enters the cavity mixing chamber through a series of slots and mixes with supersonic ͑M =3-4͒ high momentum primary N 2 flow entering the chamber through a series of cylindrical nozzles.…”

<title>Lasing in supersonic chemical oxygen-iodine lasers: recent modeling and comparison with experiment</title>

“…is the saturation parameter, ], k f = 7.8x10 -11 cm 3 /s is the forward rate constant for reaction (1) , K e = 0.75 exp(402/T) is the equilibrium constant for reaction (1) and T is the gas temperature. The intensity I is multiplied by 2 in Eqns.…”

“…High optical extraction efficiency achieved for these resonators made it possible to get high values of the chemical efficiency ~30-40%. 1 On the other hand COILs with stable resonators usually have large Fresnel numbers; hence many transverse modes oscillate, resulting in poor quality and large divergence of the extracted beam. To improve the beam quality, COILs with different kinds of unstable resonators were recently tested.…”

Improving COIL Efficiency By Iodine Pre-Dissociation Via Corona Discharge In The Transonic Section Of The Secondary Flow

“…The gain enhancement observed for small nI 2 can be explained by Heidner's mechanism of I 2 dissociation. For this mechanism iodine dissociation is an autocatalytic chain reaction accelerated by I* formed in reaction (1). Hence the dissociation rate is proportional to [I] and for small nI 2 formation of I atoms caused by electrical discharge results in much faster dissociation and larger values of the gain than in the absence of the discharge.…”