A review of recent developments in high-pressure pulsed molecular lasers is presented. Included are some experimental results on TEA lasers, E-beam lasers, and lasers using Blumlein excitation. Discussions of the kinetic modeling, the parametric behavior, and the characteristics of uniform discharges in the high-pressure pulsed CO 2 laser are given. Recent results on pulse-initiated chemical lasers, extremely high-pressure lasers, and high-repetition-rate TEA lasers are also discussed. Efforts to control and use the output from these devices are described, and an extensive list of references is given.

High-pressure pulsed molecular lasers

The addition of several Torr hydrogen to a transversely excited pulsed high‐pressure CO2 laser using continuous shaped electrodes has been found to suppress the formation of bright arcs and lead to better pulse‐to‐pulse reproducibility. The hydrogen increases the threshold energy for arc formation and leads to as much as a factor of 2 increase in the power output of the laser. The gain of the laser is also increased by the addition of hydrogen.

Effect of Hydrogen on CO2 TEA Lasers

The volume−discharge and arc−formation characteristics of a double−discharge self−sustaining TEA CO2 laser have been studied. The results indicate that the discharge is a form of high−pressure glow of limited stability. An experimental study of arc formation indicates that this may be a result of ionization and attachment instabilities which are predicted to grow in the transient discharge. A simple technique based on the experimental steady−state discharge characteristic has been used to maximize the stable energy density in a 7.5−cm gap system operating at atmospheric pressure.

Electrical characteristics of a double−discharge TEA CO2 laser

Laser action at 10. 6 μm has been achieved in CO2–N2–He gas mixtures at all pressures up to atmospheric by means of fast electrical discharges transverse to the laser axis. The atmospheric pressure of operation is very promising as the laser energy per pulse increases with pressure and the average power per unit volume is proportional to the square of the operating pressure. A brief description of a simple laser of this type, operating at atmospheric pressure is given along with some of the major achievements to date using this technique.

Transversely excited atmospheric pressure CO2 lasers

Fur die Anregung von Hochdruck-Gaslasern werden schnelle transversale Entladungen benutzt, die eine Art quasi-stabiler Glimmentladungen darstellen. Wir schlagen ein sehr vereinfachtes Modell vor, das solche Entladungen auf Grund einer Leistungsbilanz erklart. Die durch das angelegte elektrische Feld an das Elektronengas gelieferte Leistung mus der durch Stose mit den Gasmolekulen verlorenen Leistung der Elektronen gleich sein. An Hand einer numerischen Berechnung zeigen wir, das dieses Modell eine akzeptable erste Naherung darstellt, das es aber nicht zulassig ist, eine Maxwell-Boltzmann-Verteilung fur die Elektronenenergie anzunehmen. Der wahrscheinliche Grund dieser Glimmphase wird auch kurz besprochen, und wir konnen damit zeigen, warum es auserst wichtig ist, das die Anstiegszeit der angelegten Spannung auf einem Minimum gehalten wird.

B. Adam

Papers

Voltage-current characteristics of fast discharges in a HeCo2 gas mixture