nan Mainuddin

Diagnostics and Data Acquisition for Chemical Oxygen Iodine Laser

This paper focuses on the implementation of various diagnostics for optimizing chemical oxygen iodine laser. This paper also dwells on the measurement methodologies and instrumentation employed in these diagnostic systems. The prime diagnostics are for the measurement of vital species in form of iodine, singlet oxygen, and chlorine. Iodine concentration measurement (absorption at λ = 499 nm ), chlorine utilization (absorption at λ = 330 nm), and singlet oxygen yield (emission at λ = 1.27 μm) have been implemented based on optical absorption/emission principle. Furthermore, online Mach number determination, which is critical for supersonic gas flows, laser pulse detection (at λ = 1315 nm ), and flow rate measurement and control over wide range, have been carried out. A dedicated diagnostics and data acquisition system (DDAS) customized for parameter monitoring have been developed. The developed DDAS also serves the purpose of precise operation sequencing and parameter control. It is a 168-channel personal-computer-based system with customized interface electronics employing Visual C++ programming language with user-friendly graphical user interfaces. A detailed uncertainty analysis of various critical parameters has been also presented.

Real-time data acquisition and control system for a chemical oxygen–iodine laser

A user-friendly data acquisition and control system (DACS) for a chemical oxygen–iodine laser (COIL) has been developed. The system is capable of handling 117 analogue/digital channels for performing various operations such as on-line acquisition, control, display, safety measures and status indication of various subsystems. These operations are controlled either by control switches configured on a PC while not running or by a pre-determined sequence or timings during the run. The system is capable of real-time acquisition and on-line estimation of important diagnostic parameters for optimization of a COIL. The DACS system has been programmed using Advantech-GeniDAQ software. This software has also been used to convert the acquired data into graphical form. Using this DACS, more than 200 runs were given performed successfully.

Performance comparison of supersonic ejectors with different motive gas injection schemes applicable for flowing medium gas laser

A class of flowing medium gas lasers with low generator pressures employ supersonic flows with low cavity pressure and are primarily categorized as high throughput systems capable of being scaled up to MW class. These include; Chemical Oxygen Iodine Laser (COIL) and Hydrogen (Deuterium) Fluoride (HF/DF). The practicability of such laser systems for various applications is enhanced by exhausting the effluents directly to ambient atmosphere. Consequently, ejector based pressure recovery forms a potent configuration for open cycle operation. Conventionally these gas laser systems require at least two ejector stages with low pressure stage being more critical, since it directly entrains the laser media, and the ensuing perturbation of cavity flow, if any, may affect laser operation. Hence, the choice of plausible motive gas injection schemes viz., peripheral or central is a fluid dynamic issue of interest, and a parametric experimental performance comparison would be beneficial. Thus, the focus is to experimentally characterize the effect of variation in motive gas supply pressure, entrainment ratio, back pressure conditions, nozzle injection position operated together with a COIL device and discern the reasons for the behavior.

Overview of Optical Techniques for Characterization of High-Power Infrared Gas Lasers

High-power lasers typically form a multidisciplinary technological area laced with innumerable challenges in its realization as a practical system. The prime amongst them are infrared gas laser sources, such as carbon dioxide gas dynamic laser, hydrogen fluoride, deuterium fluoride laser, and chemical oxygen iodine laser. Each of these laser systems is associated with a unique as well as complex active medium environment involving intense interaction between lasing and pumping species under specific gas dynamic conditions. The parameters viz., specie concentration of the lasing, pumping mediums and other by-products, medium homogeneity, individual constituent gas flow rate, pressure and temperature at critical locations, and cavity Mach number are very crucial in determining the output of the gas laser system. It is essential to determine these parameters nonintrusively, with necessary precision so as to optimize these lasers especially in case of large-scale systems. Thus, the focus of this paper is to review and discuss the existing applicable optical detection methodologies ranging from the more established methods, such as optical absorption/emission spectroscopy, to very contemporary, such as Raman spectroscopy, cavity ring down spectroscopy, laser-induced fluorescence/planer laser-induced fluorescence, and so on, which are relevant for the diagnostic needs of gas lasers.

Data acquisition system for flowing gas lasers

The present paper describes a dedicated data acquisition system (DAS) for gas lasers in general and for chemical oxygen iodine laser (COIL) in particular. The developed DAS is a PC based 170-channel system using PCI bus and RS 485 serial communication for fast and slow data handling respectively. It comprises of Advantech PCI 1716 multi function data acquisition board and RS 485 based ADAM modules. It also includes custom built interface electronics circuits for sensors/actuators and optical diagnostics for gas concentration measurement. The application software is developed using VC++ programming language with six graphical user interfaces for facilitating single person operation.

Study of Different Nozzle Configurations for Supersonic COIL System

Supersonic chemical oxygen iodine laser (SCOIL) hasrecently proved itscapabilities against projectile targets such as missiles and rockets in the tests performed with ABL system. It is primarily a chemical based gas laser system involving extensive gas dynamics for achieving lasing action. COIL (l= 1.315 mm) is conducive for both defenseand industrial applications and the beam is optical fibre compatible. One of the chief components of a SCOIL device is the supersonic nozzle system which not only produces the desired cavity conditions in terms of Mach number and cavity pressure but is also responsible for efficient mixing of lasing [I2 + N2] and pumping media [O2 (1Dg) + N2]. The supersonic nozzle to a large extent controls the pressure recovery potential of the laser system and thereby the system volume. The present study discusses the performance of three nozzle configurations viz, slit, advanced/ ejector and winglet nozzle. The comparisons have been made in terms.

Development of compact high pressure COIL

An advanced nozzle, also known as ejector nozzle, suitable for a 500 W class COIL employing an active medium flow of nearly 12 gm/s has been developed and used instead of conventional slit nozzle. The nozzle has been tested in both cold as well as hot run conditions of COIL achieving a typical cavity pressure of nearly 10 torr, pitot pressure of ~ 85 torr and a cavity Mach number of ~2.5. The present study details the gas dynamic aspects and detailed numerical studies of this ejector nozzle and highlights its potential as a COIL pressure recovery device. This nozzle in conjunction with a diffuser is capable of achieving pressure recovery of ~ 60 torr, equivalent to the much cumbersome first stage of the pressure recovery system used in case of conventional slit nozzle based system. . Thus use of this nozzle in place of conventional slit nozzle can achieve the atmospheric discharge using single stage ejector system thereby making the pressure recovery system quite compact.