Page 71 - High Power Laser Handbook

CHAPTER 3

Chemical Lasers

Charles Clendening
Technical Fellow, Northrop Grumman Aerospace Systems,
Redondo Beach, California

H. Wilhelm Behrens
Fluid and Thermophysics Department Manager, Northrop
Grumman Aerospace Systems, Redondo Beach, California

3.1 Introduction
Some chemical reactions are known to produce reactants whose nascent
energy-level distribution is not in equilibrium in nature. Such chemical
reactions could potentially provide a convenient energy source to pro-
duce the population inversions necessary to achieve lasing.
One important reason for the interest in chemical lasers is their
use in mobile high-average-power systems. The most successful
candidates have been the hydrogen halides, especially hydrogen
fluoride (HF) and deuterium fluoride (DF), and the chemical oxygen
iodine laser (COIL) devices. Both premixed and flowing mixing
concepts have been developed. Megawatt-class continuous wave
(CW) devices based on supersonic laser cavity gas flows have been
demonstrated. There are also premixed devices that rely on electrically
or photolytically driven initiation approaches; however, the initiators
require power comparable to or greater than the laser output. Discus-
sion of such primarily electrically initiated devices is very limited in
this chapter.
There are several reasons for the interest in gas flow chemical
lasers for use in high-energy laser (HEL) devices:
1. Chemical reactions supply the energy source.
2. Heat is removed continuously from the gain medium by the
gas flow.

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