Numerical modeling of a He-Zn laser with helical hollow cathode

Derzhiev, V. I.; Karelin, A. V.; Sereda, O. V.; Stefanova, M.; Yakovlenko, S. I.

doi:10.1007/bf00329113

Cited by 13 publications

(7 citation statements)

References 8 publications

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“…In some of these sources He + 2 molecular ions play an important role in the discharge processes. Even at relatively low pressures, in the 10-100 mbar range, helium molecular ions are assumed to influence the discharge conditions and/or participate in the pumping mechanism of the He-Cd + laser [1,2] and the He-Zn + laser [3]. He + 2 molecular ions have also been found to be responsible for the excitation in the He-Ar + laser [4,5].…”

Section: Introductionmentioning

confidence: 99%

Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions

Kutasi

Hartmann

2001

J. Phys. D: Appl. Phys.

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Helium glow discharges in the p = 6-60 mbar pressure range have been investigated experimentally and by means of a one-dimensional self-consistent hybrid model. Unlike most of the hybrid models developed previously for noble gas discharges, our model also includes He + 2 molecular ions. The electrical parameters of the discharges, recorded in the experiments, as well as the electron temperature for the different discharge conditions (determined spectroscopically) have been used as input data for the hybrid model. Our studies show that He + 2 ions are present in the discharge even at 6 mbar with a concentration comparable to that of He + ions. Conversion of atomic to molecular ions and the associative ionization process are identified as main sources of molecular ions. At low pressures the He + 2 ions are principally lost at the electrodes, while at higher pressures the recombination processes become their dominant losses. As the rates of recombination processes are strongly pressure-dependent, the optical emission spectrum changes with increasing pressure and shows significant intensity of He 2 molecular bands. The contribution of He + 2 ions to the ion current at the cathode as well as their contribution to maintenance of the discharge is found to be around 10%, even at the lowest pressure of 6 mbar, where He + 2 formation in most of the discharge models is neglected.

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Section: Introductionmentioning

confidence: 99%

Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions

Kutasi

Hartmann

2001

J. Phys. D: Appl. Phys.

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“…However, under the conditions of our experiment the density of the molecular ions is even smaller than that of the atomic ions. Because the rate coefficient of the charge transfer reaction between He + 2 (Ne + 2 ) and Zn do not exceed significantly the rate of the Penning reaction (the same assumption was used in [17]), we can conclude that the effect of molecular ions is not important.…”

Section: The Exponential Decaymentioning

confidence: 87%

“…From the measured slopes f /f = 1 one can estimate the fractional ionization of zinc in the exponentially decreasing part on the base of equation (17). Using these values of together with [Zn] crit we found that the transition between the two different regions of the PC should appear approximately at the place where [Zn + ] equals the total ion density estimated for the pure helium and neon discharges.…”

Section: The Exponential Decaymentioning

confidence: 90%

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Cathaphoretic confinement of Zn evaporated into helium and neon discharges

Bánó

Horváth

Rózsa

2000

J. Phys. D: Appl. Phys.

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Cathaphoresis of Zn evaporated into the positive column of helium and neon discharges was investigated both experimentally and theoretically. The side-light intensity of the Zn-I 518.2 nm transition was recorded along a 4.5 cm long positive column discharge with an inner diameter of 3 mm. The buffer gas pressure was varied between 10 and 25 mbar while discharge currents of 20-60 mA were applied to the tube. Reasonably good agreement was found between the experimental data and the theoretically predicted axial distribution of zinc concentration in the tube. The results can be useful in the design of the cathaphoretic confinement section of the different He-Zn laser tubes and a prospective Ne-Zn laser system, which would operate in the deep ultraviolet region (210 nm).

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“…It was found experimentally that in a HC laser discharge, in the middle of the cathode, the electron density amounts to N e = 5⋅10 13 -10 14 cm -3 , about two order of magnitude larger than that in the positive column of a glow discharge [11]. Different model calculations and measurements are available (see, e.g., [12][13][14]). Gill and Webb [11], however, have found that in noble gas-metal vapor systems N e is about a factor of 2 larger than that in pure noble gas systems.…”

mentioning

confidence: 97%

Influence of spectral line broadening on the mode structure of He-Kr and He-Ar gas lasers

Dimitrijevic

Cšillag

2006

J Appl Spectrosc

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Using the semiclassical perturbation approach, Stark broadening parameters for Kr II 469.4 nm, Ar II 476.5 nm, and Ar II 480.6 nm spectral lines have been determined. The obtained results have been used for the investigation of the role of the Stark broadening mechanism on the mode properties of hollow cathode excited noble gas mixture lasers. It has been found that for the He-KrII 469.4 nm laser broadening by neutral atom collisions is large enough to explain the single-mode operation of this laser, as opposed to the He-ArII 476.5 nm laser where Stark broadening also has to be taken into account to explain this property.Introduction. In this work, the full semiclassical perturbation approach [1, 2] has been applied for the determination of Stark broadening parameters of Kr II 469.4 nm, Ar II 476.5 nm, and Ar II 480.6 nm lines and a joint laser physical application of the results obtained; namely the role of Stark broadening on the mode properties of hollow cathode excited noble gas mixture lasers is discussed.Stark Broadening Parameters Calculation. All details of the semiclassical perturbation approach [1, 2] used here for the Stark broadening parameter calculations are given in [3] and a comparison of the obtained results with existing experimental and theoretical calculations (see [4] and references therein) will be presented elsewhere. We note only that we checked the influence of the missing Kr II 7p levels and found it to be not important. The determined Stark broadening parameters for the Kr II 469.4 nm, Ar II 476.5 nm, and Ar II 480.6 nm lines are shown in Tables 1 and 2.Stark Broadening in Hollow Cathode Laser Discharges. Ionic lines can be effectively excited in a hollow cathode (HC) discharge due to the presence of high-energy electrons. It has been used since 1970 for the excitation of a lot of noble gas-metal vapor and noble gas mixture ion lasers [5].An interesting feature of the HC lasers is that they oscillate usually in a single axial mode without any optical selection. This property has been attributed to the large homogeneous line-width due to the relatively large filling pressures. Recent studies have shown, however, that, in several cases, broadening by collisions with neutral atoms is not large enough to explain single-mode operation [6], and Stark broadening has also to be taken into account [7]. Therefore it seemed to be reasonable to study the role of the Stark effect at the He-Kr + 469.4 nm and He-Ar + 476.5 nm HC lasers [8,9].The HC laser discharge. For laser purposes the discharge inside the cathode is used for the excitation. Different HC geometries are applied, most frequently "longitudinal" or "transversal" systems [10]. The typical pressure in the tube is 10-25 mbar. In a HC discharge the electron energy distribution function has generally a nearly Maxwellian low-energy part with a high-energy tail. The mean energy of the low-energy part amounts to E e = 0.1-1.0 eV, while the high-energy tail can rise up to the cathode voltage, which is commonly several hundred V. For laser exc...

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Numerical modeling of a He-Zn laser with helical hollow cathode

Cited by 13 publications

References 8 publications

Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions

Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions

Cathaphoretic confinement of Zn evaporated into helium and neon discharges

Influence of spectral line broadening on the mode structure of He-Kr and He-Ar gas lasers

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Numerical modeling of a He-Zn laser with helical hollow cathode

Cited by 13 publications

References 8 publications

Self-consistent modelling of helium discharges: investigation of the role of He2+ions

Self-consistent modelling of helium discharges: investigation of the role of He2+ions

Cathaphoretic confinement of Zn evaporated into helium and neon discharges

Influence of spectral line broadening on the mode structure of He-Kr and He-Ar gas lasers

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Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions

Self-consistent modelling of helium discharges: investigation of the role of He₂⁺ions