B. L. Wexler

14‐ and 16‐μ gasdynamic CO2 lasers

Laser action at 16 μ has been obtained between the (02°0) and (0110) levels as well as between the (10°0) and (0110) levels at 14 μ. A 9‐ or 10‐μ saturating pulse equilibrates the (001) level with either the (02°0) or (10°0) level and creates the transient 14‐ or 16‐μ inversion. Extraction efficiencies of 20% have been achieved on a single pulse. Repetition frequencies of 200 Hz have been achieved using a single Q‐switched cavity.

Measurements of gain, saturation, and line competition in an electron beam pumped high‐pressure Ar/Xe laser

Using a small electron beam device, we have observed time‐dependent competition among the 1.73, 2.03, 2.63, and 2.65 μm lines of the xenon laser in a high‐pressure argon buffer. The small‐signal gain and saturation intensity for each of these lines have also been measured. The maximum specific energy output of the laser was 1.7 J/l  and the efficiency was 2.3%.

Characteristics of the high-pressure Ar-Xe laser pumped by an electron beam and an electron-beam sustained discharge

Mechanisms of the line competition observed among the 1.73-, 2.03-, and 2.65- mu m lines are interpreted based on the gain and saturation data along with some known kinetics. The energy distribution among the lines is also investigated as a function of various operating parameters. An enhancement factor of approximately 10 was readily obtained for both electrical input energy and laser output energy in the e-beam sustained discharged. However, there is a tradeoff between enhancement factors and laser output energy due to a degradation of the laser output observed for discharge power enhancements greater than 5. The maximum output energy obtained was 4 J/l, with an intrinsic efficiency of approximately 3%. >

Electric discharge gas dynamic laser

An electric discharge gas dynamic laser in which excitation of one gas species is obtained in a plenum by use of a dc glow discharge. The gas present in the plenum is then accelerated through an array of supersonic nozzles where the laser species is injected and mixed with the primary flow. Energy transfer and lasing occur in the supersonic region of the flow. Brewster-angle windows which extend from 1 to 28 cm downstream from the nozzle exit plane enables a laser cavity or diagnostic apparatus to be positioned at a variable distance downstream from the injection point. The optics may be mounted on a motor-driven translation table so that continuous scans of the region downstream of the nozzle exit plane may be conveniently made. The present facility may easily be operated with a subsonic cavity, with an RF discharge to augment the dc plenum discharge, with all gases premixed, or with any combination of these configurations.

cw and improved pulsed operation of the 14‐ and 16‐μm CO2 lasers

The performance of the 14‐ and 16‐μm CO2 lasers produced in the electric discharge gasdynamic laser has been significantly improved by the addition of a small percentage of H2 to deactivate the (0110) level. This addition tripled the pulsed output of the laser, and 45 μJ at 14 μm and 25 μJ at 16 μm were observed. cw oscillation was achieved for the first time, with output powers of 0.6 and 0.9 W, respectively. The effect of collisional processes in limiting the CO2 density is discussed.

cw CO‐CS2, CO‐C2H2, and CO‐N2O energy‐transfer lasers

cw laser emission has been observed from CS2 (11.5 μ), C2H2 (8 μ), and N2O (10.6 μ) transitions pumped by energy transfer from vibrationally excited CO in an electric discharge gas‐dynamic laser device. Proposed energy‐transfer pathways for these three lasers are described. Supersonic expansion cooling plays a critical role in depopulating the lower laser levels in the CO‐CS2 and CO‐C2H2 systems. Maximum output powers measured for each of these systems are presented. The dependence of output power on the flow rate of the injected laser species is discussed.

High efficiency, high-energy performance of an X-ray preionized Ar-Xe laser

Improved performance has been obtained from the X-ray preionized argon-xenon laser by using a spiker-sustainer circuit to efficiently pump the discharge. An output of 420 mJ was obtained from a 0.4-L active volume at 2-atm pressure with an overall efficiency of 1%. An efficiency of 4.1% due to the sustainer contribution alone was also realized. >

D2‐CO2 and D2‐N2O electric discharge gas‐dynamic lasers

cw CO2 and N2O lasing has been obtained in a new electric discharge gas‐dynamic laser device. The device consists of a subsonic plenum discharge region where vibrational excitation occurs, a supersonic nozzle array where the laser species is injected, and a supersonic cavity where mixing, energy transfer, and lasing occur. In the present experiments both CO2 and N2O are pumped by energy transfer from D2 excited in the discharge. Comparisons are made for CO2 pumped by both N2 and D2, and N2O and CO2 pumped by D2.

VUV emission from discharge-pumped Ar supersonic jets under high-excitation conditions

The excimer laser potential of Ar supersonic jets excited by an intense pulsed discharge is studied. Excimer emission is recorded during and after the 100 ns discharge. The time-resolved emission is recorded as a function of plenum gas pressure and distance from the nozzle. A simple mechanism is proposed to account for the luminescence data. Model calculations are compared to the experimental data. >

Effects of helium addition to Ar-Xe mixtures in high-pressure atomic-transition xenon lasers

The output energy and spectral distribution of the atomic-transition xenon laser have been investigated with ternary mixtures based on Ar-Xe to explore kinetic issues and to enhance particular lines of the xenon laser pumped by an e-beam and e-beam sustained discharge. Addition of helium into the Ar-Xe mixtures increased the 2.03 mu m line energy by a factor of 3-5 while suppressing the 1.73- mu m line even during single-line oscillation. The maximum output energy obtained at 2.03 mu m was 1.2 J/L and the intrinsic efficiency was approximately 1%. Effects of neon or krypton addition have also been studied with e-beam sustained discharge pumping. >