Multidimensional modeling of transverse avalanche laser discharges: Applications to the HgBr laser

Abstract

Articles you may be interested inOptogalvanic signal in the BX system of HgBr: Effect of discharge voltage and laser power AIP Conf.A kinetic model of the sustained discharge HgBr laser Geometrical considerations are important with respect to the stability and efficiency of avalanche electric discharge lasers. Parameters such as the electrode contours and the distribution of preionization electrons affect excitation rates through the relative values of the local electric field, local depletion of initial species, and through the response of the discharge circuitry to spatially dependent conditions within the plasma. Constriction of the discharge and subsequent impedance mismatch of the discharge to the pulse forming line result from these spatial nonuniformities. In this paper geometrical effects in the mercury bromide electric discharge laser are examined by comparing the results from a multidimensional discharge and kinetics model with experimental observations. The code models electron and heavy particle kinetics and laser intensity in time and one spatial dimension: parallel to the electrodes and perpendicular to the optical axis. Quantities whose spatial dependence is perpendicular to this dimension, such as the contours of the electrodes, are accounted for through their impact on the local electric field. HgBr laser efficiency and spatial characteristics are examined as a function of stored electrical energy, the impedance of the pulse-forming circuitry, electrode contours, and profile of the preionization electron density. Parasitic discharges within the gas, but exterior to the optical cavity, are examined as a mechanism through which the magnitude of the preionization density can effect laser efficiency.

Simple model of halogen depletion in XeCl discharge pumped lasers

“…To view the consequences of a preionization non-uniformity on the homogeneity of plasma and its influence on the electric and kinetic characteristics of the discharge [24,29], we represented the plasma by 21 elements in parallels for the same conditions as in Figure 1, with a gas mixture of Ne(99.30%)-Xe(0.5%)-HCl(0.20%), for an applied voltage of 20 kV, and for the transverse non-uniformity of the preionization density shown in Figure 2. The preionization, in this case, has a transverse non-uniformity centered at the center of plasma.…”

Theoretical investigations of the influence of low-current preliminary discharge on the characteristics of a discharge-pumped XeCl*laser

“…The ratio SHC1(i) assumes values in the range from 0 to 1, where SHC1(i)=0 denotes no and HC1(i)1 complete depletion of HC1 in region i. The laser output energy density is determined according to EL (i) hv -E_ ln(i)S N (t)dt, (2) where hv is the energy of the laser photon, c the speed of light, and N1(t) the time-dependent photon density in discharge region 1, 1 the cavity length of the optical resonator, R the reflectivity of the output mirror. The maximum current density, the high-current discharge pulse duration, and the HC1 depletion degree give information about the effects of inhomogeneities on the discharge plasma.…”

“…In the frame of the model a parallel resistor description of the discharge plasma [2] has been adopted. In this kind of the model the total discharge region is divided into N layers, which are parallel to the discharge current and to the optical axis of a resonator cavity.…”

Observation and Measurement of Emission Cross-section of B2∑+1/2→ X2∑+1/2band of HgBr at 502 nm

“…Mercury bromide lasers meet most of the requirements needed for ocean optics . Efficient laser action has been observed in HgBr (B, v'= 0; X, v" = 22) at 502 nm during electrical or optical pumping of HgBr 2 vapour [2][3][4][5][6][7][8][9][10] . Since the laser transitions terminate to the high vibrational levels of the ground state, collisional quenching of these levels by foreign gases such as N 2 , Ar, He and Ne has been proposed to improve the performance of mercury bromide lasers [11] .…”