Construction and operation of high power gas lasers

In the present paper some typical gas laser construction and their performances will be described. Aspects of transition selective systems and high pressure operation will be treated

Saturation studies of the E-beam sustained discharge atomic xenon laser

In an electron beam sustained discharge xenon laser the discharge energy deposition has been varied in order to investigate the saturation effect on the xenon laser. The current density of the electron beam is varied separately in the range of 0.1-2.7 A/cm2 to obtain optimized discharge excitation conditions as a function of electron beam current density and gas pressure. An optimal fractional ionization f=3.5-4×10-5 is found, independent of the electron beam parameters. The synergy of electron beam and discharge excitation has resulted in a maximum specific energy of 15 J/l at a total gas pressure of 9 ba

Tunable sealed-off CW CO laser at room temperature

Starting from a sealed-off CO laser with a long-life output of 29 W/m in multiline operation, we developed a tunable version of this device. The system described has a discharge length of 97 cm. It was made transition-selective by using a three-mirror configuration. In this way we were able to tune the laser to more than 70 oscillating vibrational-rotational transitions of the CO molecule

Near infrared lasing transitions in Ar, Kr, and Xe atoms pumped by a coaxial e-beam

Optimizations of gas composition and input energy were performed for gas mixtures containing a buffer gas and either Ar, Kr or Xe as the lasing gas. The total gas pressure was varied between 1 and 14 bar and the input energy from 0.03 to 0.7 J/cm3. The excitation source was a small coaxial electron beam with a pumping length of 20 cm and a pulse length of 30 ns (FWHM). From an active volume of 13.3 cm3 a maximum output energy of 12 mJ was obtained from a gas mixture containing 0.3% Xe in Ar at a total gas pressure of 10 bar. The intrinsic efficiency was 0.9%

A study of the electron quenching of excimers in a KrF* laser excited by a coaxial electron beam

Measurements of the output energy, the optical pulse length and the build-up time of the laser pulse, obtained with a coaxially e-beam pumped KrF* laser, were performed varying the total gas fill pressure, the F2 content and the e-beam current from 1–5 bar, 0.1–0.8% and 13.3–26.6 kA, respectively. The maximum specific extraction energy amounts to 64 J/l. The large range of measurements, especially at low F2 concentrations, reveals the necessity to extend the kinetics of the F2 chain in the usual computer model. With the introduction of electron quenching of KrF* and ArF* by dissociative attachment the predictions are also for low F2 concentration in agreement with experiments

The optimization of the multi-atmospheric Ar-Xe laser

The quasi-steady-state conditions of the multi-atmospheric e-beam sustained Ar-Xe laser are investigated. It is observed that the duration of the stationary period depends on the e-beam current, discharge power deposition, and gas pressure. The laser efficiency can be as high as 8%. Beyond the stationary period the efficiency drops. The pulse energy with optimum efficiency depends strongly on the gas pressure. The maximum discharge efficiency of 5%-6% is at high pressure not sensitive to the input power. The best results are obtained for 4 bar with a discharge input power of 8 MW/l. The pulse duration with corresponding output energies is 12 ¿s with 10 J/l and 16 ¿s with 16 J/l for e-beam currents of 0.4 and 0.9 A/cm2, respectively. An analysis of the quasi-steady-state conditions that include the effects of electron collision mixing and atomic quenching is presented. The effects of output power saturation by the fractional ionization and atomic collisions are in agreement with the observations. The analysis clarifies the optimum performance condition

IR Recombination Lasers

The present study contributes to a better understanding of the atomic Xe laser as a powerful IR source. Several important phenomena like the dependence of both the observed optimized input power and maximum output power on the square of the gas density and also the constant fractional ionization are reported and verified theoretically. The insight in the kinetics of this system has also lead to the realization of small-size continuous systems with output powers in the range of watts. The results of the present study can be used to predict the performance of the atomic Xe laser under different operating conditions

The physics and technology of CW RF-excited Ar-He-Xe laser with output power density of 0.5 W/cm2

Research interest in the Ar-Xe laser has been strengthened considerably because this laser now produces output powers at the level of Watts and is becoming the most promising light source in the wavelength region of a few microns. The lasing occurs on the IR transitions (1.73-3.51 ¿m) between the 5d-6d manifolds of atomic xenon. Our breakthrough in this type of laser came when our results obtained with the electron beam sustained technology showed the beneficial effect of operating at high gas densities. From these observations and the accompanying modeling, the idea was supported to consider the dissociative recombination of ArXe+ or Xe2 + molecular ions with electrons as the primary channel for filling the upper laser level. Apart from this recombination process by three body collisions the increased density leads to homogeneous line broadening which has also a favourable effect on the power and efficiency. However, a homogeneous inversion density requires a homogeneous discharge in a high-density gas. This is from a technical point of view a great challenge. For continuous operation the waveguide structure with RF excitation has shown so far the best prospects for maintaining a homogeneous discharge at high densities, say above 100 Torr. The RF discharges are characterized by thin positively charged layers (sheaths) near the electrodes. They play an important role in the stabilisation of the discharge. At increasing current density the discharge switches from ¿- to ¿-mod

Gas-discharge XeF* (B→X) laser with high specific output energy

The discharge characteristics of the XeF* (B→X) laser are investigated. The NF3 and Xe partial pressure of the laser gas mixture and the total gas pressure have been varied. A highest specific output energy of 4.7 J/l with an efficiency of 0.5% was obtained from a X-ray preionized Ne/Xe/NF3 gas mixture at 6 bar with single-pulse excitation through a multichannel spark gap

Intrinsic efficiency and critical power deposition in the e-beam sustained Ar:Xe laser

Experimental investigations on an e-beam sustained near infrared Ar:Xe laser have been carried out to determine the intrinsic efficiency at optimized conditions. A parametric study at different sustainer currents reveals a maximum output energy depending on current density. Up to 8 bar the optimized laser output power per unit volume increases linearly with 1.1MW/1 bar. Intrinsic efficiencies of up to about 8% are feasible