The rate of generation of O₂(¹(Delta) _g) using the chlorine-basic hydrogen peroxide reaction is a key element to predict the performance of the chemical oxygen iodine laser. O₂(¹(Delta) _g) carries the energy in the laser, thus it is one of the prime determinants of power in the flow. To predict the performance of O₂(¹(Delta) _g) generators requires the prediction of the utilization of chlorine, the yield of excited oxygen, and the concentration of potential contaminants in the chemical exhaust of the generator. This paper is an extension of a previous paper on this same topic. The reader is also referred to a companion paper in this conference which discusses the details of O₂(¹(Delta) _g) production and yield.

A computational study including sensitivity, non-dimensional, and steady-state analyses of the gas phase kinetics associated with chemical oxygen-iodine lasers (COIL) was performed to develop simplified kinetic models and assess kinetic limitations to laser performance. A minimal set of eleven reactions is presented that adequately reproduces the time evolution of the major chemical constituents as described by the standard COIL kinetic model. The impact of poorly determined rate coefficients is assessed through a linear sensitivity analysis. By transforming the rate equations to a non-dimensional form, scaling laws for iodine fraction, singlet oxygen yield, and water content are developed. Finally, an approximate analytic solution to the iodine dissociation problem is established for a broad range of reagent concentrations. The current study is limited in applicability due to the exclusion of chemical heat release, fluid dynamic, and reactive mixing phenomena.

A mathematical model for the production of singlet delta oxygen from the reaction of a gas containing chlorine with the hydroperoxy ion in liquid basic hydrogen peroxide is reviewed. An exact solution for the Cl₂ utilization, O₂(¹(Delta) ) yield, and efficiency of the generator is obtained in the well-stirred limit (WSL) for which the surface concentration of HO₂^- is constant. A universal set of performance curves is presented and the implications when assessing generator performance are discussed. When depletion of the surface concentration of HO₂^- is important, perturbation theory is used to obtain a solution for the generator's utilization, yield, and efficiency which is a generalization of the corresponding WSL solution. A criterion for the validity of the perturbation solution is obtained and it is shown that the performance of a rotogenerator plateaus not too far above the value of disk rotation rate predicted by this criterion. Finally an integral method is used to obtain a simple, but approximate, solution of the utilization-yield equations which applies over a wide range of operating conditions.

A gas-sampling diagnostic has been developed to determine the molecular composition in real time of the gaseous flow emanating from a ¹(Delta) _g oxygen generator. This excited state oxygen is the energy source for a chemical oxygen-iodine laser (COIL). The major constituents in the flow, helium, oxygen, chlorine and water are drawn from the generator and transported to a quadrupole mass spectrometer for analysis. Information derived from this instrument such as chlorine utilization, water vapor content and flow impurities will advance our understanding of the oxygen generator performance. Precise measurements of water content are particularly important because of its energy quenching effect on I^*, the lasing species in a COIL. This diagnostic may also be used to measure the mixing distribution of molecular iodine in the supersonic excited oxygen flow downstream of the nozzles. This paper discusses the criteria for the design of the gas-sampling diagnostic.

An intermediate-size module that will serve as a building block of an advanced high-power HF/DF chemical laser is described. The module is based on an optimized hypersonic, low- temperature (HYLTE) nozzle concept. The primary objective of the program is a high- efficiency, high-power demonstration of HF overtone lasing. The resulting device is called overtone research advanced chemical laser (ORACL). A secondary objective is an improved chemical laser gain generator for HF fundamental and DF lasing.

In order to operate weapon-level chemical lasers, such as DF or COIL, or test articles, such as the Alpha HF chemical laser, in the atmosphere it is necessary to recover as much of the velocity component of the flow and convert it to pressure as possible. This conversion is accomplished through diffusers which decelerate the flow from supersonic to near zero velocities. Subsequent pressure increases to atmospheric levels, if required, are normally accomplished with ejectors. In a size limited carrier vehicle or test area it is desirable to design diffusers which are as small and compact as possible and still maintain optimum performance. One method of reducing the size of supersonic diffusers is to employ vanes to reduce the effective inlet duct dimension (D) and thus the length (L), since L/D equals Constant for a given inlet Mach number. This paper presents a tutorial on diffuser theory as well as experimental results from both TRW and UTRC on vaned diffuser performance. The results emphatically show that vanes are only effective when they reduce the inlet duct dimensions perpendicular to the limiting boundary layer.

This paper describes continued modeling efforts of the Aerospace Corporation's Integral Master Oscillator Power Amplifier (IMOPA) line selection concept for HF and DF chemical lasers. The initial goal was to examine the potential use of the IMOPA for the Mid-Infrared Advanced Chemical Laser (MIRACL), and secondly, to anchor and support modeling efforts on the Aerospace line selection design and experimental efforts.

A promising candidate for a visible-wavelength chemical laser is the NCl molecule in the b¹(Sigma) electronic state, emitting at 665 nm. This state can be generated by purely chemical methods. The energy-pooling reaction, NCl(a¹(Delta) ) + I^*(P_1/2) yields (b¹(Sigma) ), is estimated to have a rate coefficient of 1 X 10¹¹ cm³/sec from a steady-state approximation. Experiments using a high speed flowtube have shown that NCl(a1(Delta) ) is generated in high yield via the reaction of HN3 with chlorine atoms. The measured yield is 65%. Preliminary measurements of gain were initiated employing the cavity ring-down technique. These experiments indicate that gain may be present under the operating conditions used. Confirmatory experiments are in progress.

Kinetic modeling of the reactions that occur when molecular fluorine is mixed with the perfluoroalkyl iodides, RI, where R is methyl, ethyl, or n-propyl has been performed. The model that is utilized indicates that complex formation occurs initially in an extensive series of radical chain reactions. Wall reactions are incorporated into the kinetic mechanism and account in large measure for the formation of perfluoroethane during the reaction with the methyl homolog.

Transient radiation-induced absorption losses in laser materials have been measured using a pulsed nuclear reactor. Reactor pulse widths of 70 to 90 microsecond(s) and absorbed doses of 1 to 7.5 krad have been used. Transmission recovery times and peak absorption coefficients are given. Materials tested include LiNbO₃, GSGG, silica substrates, and filter glasses used in the laser cavity. The filter glasses are tested at discrete wavelengths in the range 440 - 750 nm. Lithium niobate, MgO-doped LiNbO₃, GSGG, and the silica substrates are tested at 1061 nm.

A rectangular laser beam of uniform intensity is very suitable for laser photochemistry. In this paper, we propose a beam-forming system that consists of two deformable mirrors. One of the mirrors changes the beam intensity and the other compensates for phase distortion. We simulate the beam-forming property using a Fresnel equation solved by a Fourier transformation. We reshaped a Gaussian-like He-Ne laser beam into a beam with a more uniform intensity profile by a simple deformable mirror.

The scaling theory is exploited for a cw chain HF laser initiated by a stationary detonation wave. This provides us with a fast and accurate method of estimating the output parameters of the laser at different compositions of the initial mixture. The comparative analysis to numerical simulation is performed and demonstrates a reasonable degree of accuracy using our method.

If a short laser pulse with high intensity is focused on the surface of a target in vacuum, it causes a nearly instantaneous vaporization of a limited volume of material. The rapid expansion of this material vapor produces an impact at the surface. The shock wave propagates and is absorbed in the material. In certain alloys, this causes work hardening, an increase in dislocation density, and phase transformations. While most material is vaporized, some surface melting occurs. The rate of re-solidification of the molten material is such that an almost completely amorphous structure results. The martensitic transformation in the solid target has been confirmed by using optical and transmission electron microscopy and by electromagnetic detection techniques. An iodine photodissociation laser emitting at the wavelength of 1315 nm was used for the experiments. The pulse length was typically 1 ns and the pulse energy could be varied between 1 and 30 Joules. The energy and power density in the focused spot were larger than 3 X 10³ Jcm^-2 and 3 X 10¹² Wcm^-2, respectively. Calculations of impact/momentum, peak pressure, and peak temperature were performed using the finite difference method with moving boundaries. The effects of the iodine laser pulses are compared with those of Q- switched Nd:YAG and ruby laser pulses.

The T-1028A/FPS-85 transmitter is part of the AN/FPS-85 phased-array radar system located at Eglin Air Force Base, Florida. The radar features an electronically steerable beam at a peak radiated power of about 32 MW generated by a 72 X 72 matrix of separate T- 1028A/FPS-85 transmitter elements that are individually rated for a maximum peak power output of 10 kW. The output stage RF amplifier is a cavity design that uses the YU-176 planar triode tube. The signals to modulate the tube cathode are developed within the transmitter. This departs from the original transmitter design philosophy in which all 5184 transmitter units were modulated by single-signal sources that originated from centralized equipment locations and were then fed to the transmitter elements by an extensive network of cables and feed boxes. Recent improvements in technology have made small and inexpensive switching components available which allow for individual pulsed power and modulator circuits. The proposed retrofit of the radar site with the redesigned transmitters will result in the obsolescence of the existing modulator equipment.

The AN/FPS-85 radar is a large, fixed-position, phased-array radar located at Eglin Air Force Base, Florida. The radar has a peak radiated power of about 32 MW generated by a 72 X 72 matrix of separate transmitter elements that are individually rated for a maximum peak power output of 10 kW. All current amplifier and mixer functions on the existing transmitters are performed by tube devices. Southwest Research Institute is currently under contract by the U.S. Air Force to redesign the transmitter units and supply three operational prototypes. The design goals of the program are to extend the performance envelope by increasing pulse width and duty cycle capabilities, and to increase the reliability of the transmitter by using solid-state components where practical. The transmitter prototype redesign is in an advanced state and has involved the design of pulsed-power modulator circuits, energy storage networks, and custom solid-state and tube cavity amplifiers. An industry search for suitable manufacturers of custom RF amplifier modules has resulted in the conclusion that an all-solid-state design is technically viable; however, the expense of the all-solid-state approach has made a combined solid-state/tube design economically attractive.

During the last years a variety of devices for beam diagnostics of high-power CO2 lasers have been developed enabling to measure different parameters like the beam power, the spatial intensity distribution, the state of polarization or different geometrical values such as beam diameter and beam divergence. This paper gives a short overview of the state-of-the-art in CO2 laser beam diagnostics, points out future perspectives and presents two new measuring systems. In search of facilities for a cost-efficient measurement of the beam position and beam diameter in industrial laser beam delivery systems a flexible device for this task has been developed. The apparatus operates with moving thermocouples and is small and rigid. Under aspects of mirror-allgnement and the control of significant beam parameters during processing the system has a modular design with the ability to connect several measuring devices with one central control unit. The investigation of dynamic interactions between the laser beam and the process in case of laser beam welding and cutting reveals the necessity of measuring the intensity profile with a time resolution up to several kHz. Due to the lack of time resolution of available diagnostic systems the development of a high-speed laser beam intensity-profiler based on a room-temperature MCT detector-array and real-time data analysis will be described. By the use of a partially transmitting mirror in the beam delivery system it is possible to perform beam diagnostics during materials processing. Measurements of the intensity profile can be obtained with repetition rates up to 10 kHz and will be analyzed on-line to characterize the temporal stabifity of the laser beam.

The paper reviews the results on excimer- and carbon-dioxide-laser-produced plasma studies. Laser supported detonation waves were studied both experimentally and theoretically. Good agreement was achieved between the results of the computer and real laboratory experiments. The dynamics of LSDW in the moving TEA carbon dioxide laser beam were investigated. The Raleigh-Taylor instability of the 20 nanosecond XeCl laser produced erosion plasma dynamics in the low pressure ambient gas was observed.

The present report is dedicated to a problem o a cnto1 arid a measurement or laser radiation energy parameters The method SOr1O-l 'lt1C IS a iogic'ai oontmuation uf an mterfern aporoacn expained in detail in our article. An essence of the interference approach is a creation of a thermal field in a volume—absorbing medium by the radiation uncier investigation and studying of this field in an interferometer by a probing laser of a visible spectral rarge. iowever phase heterogeneity arised in an absorbing medium as a result of laser radiation propagation may be VisUaliZed not Only by means of the interference methods but also by ug:jn o di fferent mOdifioa t ions o f schi ieren and shadow me thods. Just this version of recording is a subject of the present report.

The experimental and numerical calculation results of nonlinear properties of quasioptical magnetoresonance structure in nonstationary regime are presented. The theoretical analysis has been carried out for the system of planeparal1e1 paramagnetic layers under the electron spin resonance (ESR) conditions at low temperatures (T 4.2 K).Such space is placed between two plane metal mirrors. The experimental results were Obtained by using a two-mirror quasioptical resonator with the paramagnetic layer inside it. Experiments were carried out in 4-mm wavelength range and at radiophysical low and superlow temperatures T< 1 K. Analytic theoretical studying of the development of the process of paramagnetic resonance absorption taking into account the influence of such spin system on the nonlinear properties of the structure under investigation is presented too. The comparison of experimental results with the theoretical date allows to conclude that we have qualitative agreement of the mathematical model and real situation.

Pressure pulsations appear on solid surfaces during the interaction of laser pulses. We use a computer to obtain solutions to the 2D Navier-Stokes equations, representing axisymmetric unsteady jet modeling an erosive plume. We analyze the gas dynamics only, without looking after ionization processes, boiling, and so on. Significant pressure pulsations arise, depending on irradiation conditions and properties of the irradiated substances, and we discuss them in comparison with experimental data.

The results of theoretical investigation of radiation spatial properties for chemical oxygen- iodine laser supplied with an unstable telescopic resonator containing a Gaussian output coupler has been obtained. The calculated field has a smooth profile in cases of practical interest. In the far field, laser radiation is concentrated mostly inside one lobe and its width is near diffraction limit. According to these results it's very probable that such a cavity would form a high-quality beam for other lasers with preliminary excited gas flow active mediums.

The results described in the paper clearly show that a plasma plume produced under conditions typical for laser-assisted materials treatment has a complicated spatial and temporal structure. Numerous 2D processes affected the beam propagation through the plasma leading to spatial and temporal energy redistribution on the target surface which affects both efficiency and quality of material processing at intensity level in the range from 10⁷ to 10¹⁰ W/cm². It is also demonstrated that the `target-plasma-laser' feedback arising during laser processing of metal targets can disturb temporal distribution in the incident laser pulse causing output power modulations at several MHz with perturbation depth more than 50%. The feedback effect proves to be responsible for spatial and temporal distribution of the radiation on the target surface and affects laser beam quality, dynamics, and optical properties of low-threshold low-temperature breakdown plasma with the electron density ranging from 10¹⁷ to 10¹⁹ cm^-3. Experiments were carried out in a wide range of parameters using microsecond pulses of CO₂ and XeCl lasers. Diagnostics used in the experiments provide appropriate spatial and temporal resolution (0.1 mm and 10 ns, respectively). Adequate modeling, self-consistent or combined, is applied to explain and interpret experimental data.

Basic Hydrogen Peroxide (BHP), the principle fuel for Chemical Oxygen-Iodine Lasers, was completely regenerated by the direct addition of potassium superoxide. The researchers successfully returned the reactive hydroperoxide ion, 02H, to its original molarity. This novel regeneration method is compared with a regeneration technique using potassium hydroxide and hydrogen peroxide. The initial generation of BHP using these standard mixing reagents is compared to generation using potassium superoxide with a protic mineral acid.