Appl. Phys. B 50, 439~440 (1990) Applied physics

Physics B "" Chemistry

© Springer-Verlag 1990

Editorial

Laser Diagnostics in Combustion

The drastic increase in the consumption of primary fossil energy has created a situation in which local and global environmental effects such as acid rain and warming of the atmosphere can no longer be neglected. Non-intrusive optical methods for measuring temperature, species concentrations and gas velocity in combustion processes are particularly valuable tools in the effort to improve energy conversion and simultaneously reduce the emission of pollutants in combustion processes. The call for papers for this special issue of Applied Physics B resulted in an overwhelming response, which has made it necessary to distribute the contributions between the present and the following issue (see list of forthcoming papers on next page).

The major part of the material is devoted to the application of laser-induced fluorescence (LIF) and coherent anti-Stokes Raman scattering (CARS). Detailed dis- cussions on the principles, advantages and limitations of these methods have been included as well as reports on a large number of specific applications, ranging from steady low- pressure premixed flames to unsteady high-pressure engine combustion. The reader new to the field will find here an introduction to the major techniques, while the specialist will learn about methods for application in extreme conditions (e. g., 2 500 bar, 3 200 K) and new applications of tunable excimer lasers for Raman scattering or simultaneous nmltispecies single-shot imaging by two-wavelength laser operation. New opportunities for sensitive detection of free radicals by stimulated emission spectroscopy and degenerate four-wave mixing (DFWM), chemical analysis of droplets by stimulated Raman scattering, and multidimensional measurement of gas velocities and temperatures are described. Several contributions investigate the simultaneous use of different methods in order to evaluate their specific advantages and shortcomings.

It is encouraging to see the intensifying worldwide activity in employing sophisticated laser spectroscopic methods in the harsh environment of practical combustion systems. This offers us some hope in dealing with the difficult task of reducing emission into the atmosphere from combustion processes.

I would like to thank all the contributors for their efforts to describe the present state of the art in this field, which will hopefully stimulate further work. It was also a great pleasure for me to work in very efficient collaboration with Dr. A.M. Lahee of Springer- Verlag.

March 1990 J. Wolfrum

440

To appear in Laser Diagnostics in Combustion H (Appl. Phys. B 51/1 1990):

R. Miles, W. Lempert: Two-Dimensional Measurement of Density, Velocity and Temperature in Turbulent High-Speed Air Flows by UV Rayleigh Scattering

W. P. Aeker, A. Serpengiizel, R. K. Chang: Stimulated Raman Scattering of Fuel Droplets: Chemical Concentration and Size Determination

B. Attal-Tr~tout, P. Bouchardy, P. Magre, M. P~alat, J.P. Taran: CARS in Combustion: Prospects and Problems

S. Kr~ll, P.-E. Bengtsson, M. Alden, D. Nilsson: Is Rotational CARS an Alternative to Vibrational CARS for Thermometry

F.M. Porter, D.A. Greenhalgh, P.J. Stopford, D.R. Williams, C.A. Baker: A Study of CARS Nitrogen Thermometry at High Pressure

R.W. Dibble, S.H. Starner, A.R. Masri, R.S. Barlow: An Improved Method of Data Aquisition and Reduction of Laser Raman-Raleigh Scattering from Multispecies

J.A. Shirley: UV Raman Spectroscopy of H2-Air Flames Excited with a Narrowband KrF Laser

W. Ketterle, A. Arnold, M. SchMer: Two-Wavelength Operation of a Tunable KrF Excimer Laser a Promising Technique for Combustion Diagnostics

A. Arnold, W. Ketterle, H. Becker, J. Wolfrum: Simultaneous Single-Shot Imaging of OH and 0 2 using a Two-Wavelength Excimer Laser

G. Marowsky, G. Liipke: CARS-Background Suppression by Phase-Controlled Nonlinear Interferometry

B. Lange, J. Wolfrum: The Impact of Laser Field Statistics in Determination of Temperature and Concentration by Multiplex USED-CARS

R. Bombach, T. Gerber, B. Hemmerlin, W. Hubschmid: Aspects of Hydrogen CARS Thermometry

N. Wenzel, B. Lange, G. Marowsky: High Temperature N2-CARS Thermometry

M.J. Cottereau, F. Grisch, J.J. Marie: CARS Measurements of Temperature and Species Concentration in an IC Engine

G. Zizak, F. Cignoli, S. Bencchi: A Complete Treatment of a Steady-State Four-level Model for the Interpretation of OH Laser Induced Fluorescence Measurements in Flames

A. Leipertz, E. Magens: Flame Diagnostics by Pure Rotational CARS

W. Meienburg, H. Neckel, J. Wolfrum: In Situ Measurement of Ammonia with a 13COz-Waveguide Laser System