Spectroscopic investigation of the plasma of a high-current diffuse discharge in He/Ar/CF2Cl2(CCl4) mixtures

Survey emission spectra in the region of 190–600 nm and time and service-life characteristics of a transverse nanosecond discharge in He/Ar/CF₂Cl₂(CCl₄) mixtures at a pressure of 10–100 kPa are investigated. In the emission spectra, excited products of the decomposition of freons—C₂(A−X), CN(B−X), Cl ₂ ^* , C^*, Cl^*, and Cl^+*— and the emission of ArF at λ=193 nm are revealed. The emissions of Cl ₂ ^* at λ=258 nm and ArF at λ=193 nm were the most intense. The discharge in the He/Ar/CF₂Cl₂ mixture is a multiwave emission source with λ=258 nm Cl ₂ ^* 193 nm ArF, and probably, 175 nm Arcl. It is of interest for applications in UV-VUV-range pulse photometry. The duration of the emission on Cl ₂ ^* , ArF, ArI, ClI, and ClII transitions in the discharge in the Ar/CF₂Cl₂ mixture (P=10–20 kPa) was 200–300 nsec. With adding He and increasing pressure to 100 kPa the duration of the emission decreased by a factor of 1.5–2. The basic mechanisms of the formation of Cl₂, ArF, and CN(B) molecules in the transverse-discharge plasma are considered. Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal. Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 241–246, March–April, 1999.     

First lasers created at the Institute of High Current Electronics of the Russian Academy of Sciences (Siberian Division)

This paper presents the designs and radiation characteristics for lasers operating by self-limited transitions of nitrogen (λ=337.1 nm) and neon (λ=614.3 nm) and pumped by a pulsed longitudinal discharge, and for atmosphericCO ₂ lasers (λ=10.6 μm) pumped by a transverse electron-beam-initiated discharge or by a transverse discharge with uv preionization. These lasers were put into operation at IHCE in 1969 (the nitrogen and neon lasers), in 1971 (theCO ₂ laser pumped by an electron-beam-initiated discharge), and in 1972 (theCO ₂ laser pumped by a transverse discharge with uv preionization). Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 14–17, August, 1999.     

Emissivity of the pulsed capacitive discharge in helium-iodine and neon-iodine mixtures

The emission parameters of a pulsed capacitive discharge initiated in helium-iodine and neon-iodine mixtures are reported. The discharge plasma emits at wavelengths of 183.0 and 206.2 nm, which correspond to iodine atom spectral lines. The capacitive discharge is initiated in a cylindrical quartz tube with an electrode distance of 10 cm. The discharge radiation is optimized in exciting pulse repetition rate and helium and neon pressures in He(Ne)-I₂ mixtures. The optimal pressures of helium, neon, and iodine vapor fall into the ranges 0.8–2.0 kPa, 0.5–1.0 Pa, and ≤60 Pa, respectively.     

Transverse discharge with prebreakdown ionization multiplication of electrons in the working media of N2- and HF-lasers

Results of an investigation of the characteristics of a transverse discharge with prebreakdown ionization multiplication of electrons in the working media of N₂(C-B)-and SF₆/H₂ chemical HF-lasers are reported. The conditions of initiation of a stable volume discharge in the discharge gap with low homogeneity of the electrical-field distribution are investigated. A quasisteady plasma based on N₂ molecules with a radiation duration of ≤0.5 μsec at transitions of the 2⁺-system and a homogeneous discharge in a SF₆/H₂=(3–7)/(1–2) kPa mixture, which is of interest for preionization of the working medium of an HF-laser by the predischarge method, are obtained. Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 412–415, May–June, 1999.     

Multiwave excimer lamps using XeF/XeCl/KrF/KrCl molecules

Results are presented of an investigation of the spectral and temporal characteristics of an electricdischarge excimer lamp emitting simultaneously on the 351 nm XeF, 308 nm XeCl, 249 nm KrF, and 222 nm KrCl transitions. The He/Kr/Xe/SF₆/HCl working mixtures were excited in a transverse discharge with ultraviolet spark preionization at a total pressure of 25–100 kPa. In order to obtain the same brightness the concentration ratio [Kr]/[Xe] for the excimer molecular transitions was 8/0.8 kPa, and that for the halogen-containing molecules was [SF₆]/[HCl][=[0.06–0.12]/[0.08–0.16] kPa. The duration of the radiation pulses for the excimer molecular transitions at atmospheric pressure was 100–200 ns and when the total mixture pressure was reduced to 250 kPa, this was doubled or trebled. The service life of the spontaneous radiation for B-X transitions in excimer molecules was 10⁵ pulses. Zh. Tekh. Fiz. 68, 64–67 (December 1998)     

Mercury-free emitter pumped by a krypton fluoride molecule pulse-periodic barrier discharge

The characteristics of a pulsed-periodic short-barrier-discharge emitter operating at wavelength λ = 248 nm KrF(X-B) are investigated. The operating mixtures of the UV lamp are low-aggressive krypton-sulfur hexafluoride (SF6) mixtures at a total pressure in the range 1–50 kPa and a SF₆ partial pressure of 0.1–0.4 kPa. The spectral characteristics of the plasma are studied, and the 248 nm KrF(X-B) band luminosity is optimized in terms of the operating mixture composition, pump voltage, and pulse repetition rate. The mean power of UV emission from the lateral surface of the cylindrical lamp is estimated.     

Multiwave electric-discharge radiator for the 175–258-nm region

The radiation spectra of plasma in the region of 130–350 nm and the intensities of the 175-nm ArCl, 193-nm ArF, and 258-nm Cl₂ bands produced in the transverse volume discharge on a mixture of Ar/CF₂Cl₂ = (1–15)/(0.008–0.150) kPa are investigated. The discharge is shown to be a multiwave source of UV-VUV radiation on transitions of ArCl, ArF, and Cl₂ molecules. The optimum content of Freon-12 molecules is 0.008–0.010 kPa and that of argon atoms 10–15 kPa. The ratio of the intensities of the ArCl (B-X) and ArF (B-X) bands is 10, which is approximately equal to the ratio of concentrations of [Cl⁻] and [F⁻] ions, which are formed in the reaction of dissociative electron attachment to CF₂Cl₂ molecules. The service life of a radiator with λ = 175 nm of ArCl on one mixture in a gas-static mode is not greater than 5·10³ pulses. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 3, pp. 407–408, May–June, 2000.     

Optical characteristics of the plasma of a transverse volume discharge in Cl2 and He/Cl2 mixtures

Results are presented from a study of UV and VUV emission from the plasma of a transverse volume discharge in chlorine and a He/Cl₂ mixture. In the wavelength range Δλ=140–300 nm, the Cl₂(D′-A′) band with an edge at 258 nm and the Cl ₂ ^* band with edge at λ=195 nm are found to be dominant. It is shown that, in the pressure range [Cl₂]=0.1–2.0 kPa, the intensity of emission with λ≤195 nm is higher than the intensity of the Cl₂(D′-A′) band. At [Cl₂]≥2 kPa, emission in the 258-nm band is dominant.     

Characteristics of negative corona discharge in the working media of atmospheric-pressure nitrogen lasers

We present the results of investigations of the electrical and optical characteristics of a negative-polarity corona discharge excited in systems of “pins-mesh” and “pins-plane” electrodes in a He/N₂ mixture at atmospheric pressure. In order that such a corona discharge could be applied in systems of electric pumping of the working medium of atmospheric-pressure N₂-lasers, the optimum conditions should be: the total pressure of the mixture ≤150 kPa and the nitrogen pressure ≤5 kPa. Uzhgorod State University, 46, Pidgirna St., Uzhgorod, 290000, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 837–840, November–December, 1997.     

Electron-beam-pumped infrared and visible lasers

This paper presents the results of investigations of lasing by electronic transitions of xenon, krypton, and neon atoms, cadmium and zinc ions, and nitrogen molecules and by oscillatory transitions of HF molecules. The processes responsible for the efficiency of each of the lasers have been studied. The maximum radiation energies achieved are as follows: up to 200 J at λ∼2.8 μm for a mixture of H₂−SF₆, up to 100 J at λ-1.73 μm and up to 50 J at λ=2.03 μm for xenon, up to 3 J at λ=358 nm for a mixture of Ar−N₂, and up to 0.5 J at λ=585.5 nm for neon. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 34–44, April, 2000.     

Radiative characteristics and kinetics of processes in low-pressure gas-discharge lamps based on a mixture of helium and iodine vapors

The UV radiation of glow- and capacitive-discharge lamps based on mixtures of inert gases with iodine vapors are optimized in the spectral range of 175–360 nm, in which working helium-iodine mixtures of different compositions are used. The most intense spectral lines in the bactericidal region of the spectrum were the atomic lines of iodine (183.0, 206.2 nm), and in the region of 320–360 nm, emission of the spectral band of an iodine molecule prevailed with a maximum at λ = 342 nm. For a capacitive lamp with a casing opaque in the spectral range λ < 250 nm, the main part of the plasma emission power is concentrated in the A′-D′ band of an iodine molecule with a maximum at 342 nm. The emission brightness of this lamp is optimized in iodine molecule transitions depending on the partial helium pressure. We present the results of simulating the kinetics of processes in a glow-discharge plasma in mixtures of He, Xe, and iodine vapors. We establish the dependence of the main part of the emission intensity of the 206.2 nm spectral line of an iodine atom and the 342 nm band of an iodine molecule on the helium pressure in a glow-discharge lamp operating on a He-I₂ mixture.     

Source of far and vacuum ultraviolet radiation based on a transverse high-frequency discharge

We present the results of an investigation of a short-wavelength radiation source (Δλ = 130–350 nm) with excitation by a transverse high-frequency (f = 1.76 MHz) discharge based on a mixture of argon and chlorine (p = 100–500 Pa). We have studied the spectral characteristics of the plasma, the oscilloscope traces of the voltage, the current and emission of the discharge, the dependence of the power of the emission on the electrical power of the discharge, and also the pressure and partial composition of the Ar/Cl₂ mixture. The UV-VUV source emits in a system of broadened and overlapping ArCl(B/X), Cl₂(D′/A′), and Cl**₂ molecular bands. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 648–651, September–October, 2007.     

RF exciplex halogen source of UV radiation on an argon-xenon-chlorine mixture

An exciplex halogen source of UV radiation that is excited by an rf transverse discharge is studied experimentally. The active medium of the source is an Ar-Xe-Cl₂ mixture kept at a low pressure (100–1000 Pa), and its working spectral range is 220–450 nm. The radiation spectrum contains 235 nm XeCl(D-X), 257 nm Cl₂(D′-A′), 306 nm XeCl(B-X), 390 nm XeCl(C-A), and 430 nm XeCl(B-A) lines. The results of optimization of the UV power as a function of the pressure, Ar-Xe-Cl₂ mixture composition, and excitation power are reported.     

Parametrical conversion of the frequency of organic lasers into the middle-IR range of the spectrum

The possibility of parametrical conversion of visible radiation of solid-state organic lasers into the middle-IR range of the spectrum in nonlinear GaSe_1–x S _x (x = 0‒0.13) crystals is investigated. Generation at the difference frequency (wavelength λ₃ = 9.43 μm) of induced oxazine-1 (at λ₁ = 740 nm) and rhodamine-800 (λ₂ = 803.4 nm) radiation is excited. The conversion efficiency is estimated, and prospects for its further increase are demonstrated.     

Anomalous light-induced drift of lithium atoms in a mixture of noble gases

This paper is a theoretical study of the spectral features of the velocity of light-induced drift (LID) of lithium atoms (⁷Li and ⁶Li) in a binary mixture of noble gases: Ne + Ar, Ne + Kr, and Ne + Xe. The spectral shape of the LID signal is predicted to depend strongly on the fraction ξ of neon in the buffer mixture in the range ξ≈0.8–0.9 (ξ=N _Ne/N _b, where N _Ne is the neon concentration, and N _b is the total concentration of the buffer particles). When the velocity of anomalous LID is treated as a function of the radiation frequency, it is found to have one, three, five, or seven zeros and to differ substantially from the dispersion-curve-like behavior with one zero predicted by the standard LID theory with velocity-independent transport collision rates. The reason for these additional zeros of the drift velocity is the alternating-sign dependence on the lithium-atom velocity of the relative difference of transport rates of collisions between buffer particles and excited and unexcited atoms. What is also established is that the anomalous LID of lithium atoms can be observed at almost all temperatures, depending on the value of ξ. At a fixed temperature, anomalous LID can be observed only in a narrow range of values of the fraction of neon in the buffer mixture, Δξ≈0.02. The results make possible highly precise testing in the LID experiments of the interatomic potentials used in calculations of the velocity spectrum of anomalous LID. Zh. éksp. Teor. Fiz. 116, 1587–1600 (November 1999)     

Spatiotemporal spectroscopic diagnostics of a pulse-periodic strontium vapor laser

Results of spectroscopic investigations into plasma of a pulse-periodic strontium vapor laser operating in the superradiance mode on the infrared transition at λ = 6.45 μm are presented. The method of determining the electron temperature and concentration as well as the gas temperature – T _e , n _e , and T _g – based on measuring the absolute intensities of some SrI and SrII and buffer gas (helium or neon) spectral lines is used. Time dependences of the line intensities during a current pulse (τ = 150 ns) and near afterglow (up to 3 μs) are obtained under conditions of non-equilibrium plasma ionization and recombination. The optical system collects radiation from the entire length of the plasma column by means of separating radial volume zones, includingthe central zone and the zone closer to the walls, with the monochromator slit. The results obtained allow us not only to calculate T _e , n _e , and T _g values, but also to trace the spatiotemporal plasma evolution.     

Emission properties of a pulsed-periodic barrier discharge initiated in helium-iodine and argon-iodine mixtures

The subject of investigation is the emission properties of a pulsed-periodic barrier discharge initiated by submicrosecond pulses (f = 40–1000 Hz) in He-I₂ and Ar-I₂ mixtures. The investigation is carried out in the spectral range 200–400 nm at a pressure of the working medium of 1–100 kPa and an iodine partial pressure of 130–200 Pa. The dependence of UV emission from the plasma of the barrier discharge at the 342 nm I₂(D′ → A′) band and the iodine atom spectral line at 206.2 nm on the argon and helium partial pressures, excitation pulses repetition rate, and charging voltage of the capacitor of a short high-voltage pulse modulator is optimized. The contribution of the 206.2 nm I* spectral line to the UV emission of the barrier discharge is estimated.     

Emission characteristics of a discharge iodine vapor plasma in the spectral region of the main absorption maximum of DNA molecules

Radiation of glow and capacitive discharges in inert gas-iodine vapor mixtures is studied in the spectral range 150–210 nm, which coincides with the main absorption maximum of the DNA molecules. Iodine atomic spectral lines at 150.7, 161.8, 170.2, 183.0, and 206.2 nm are observed in the spectra. The emission intensity of the iodine spectral lines is optimized by varying the glow discharge current, capacitive discharge frequency, as well as pressure and composition of the gas mixtures. The glow and capacitive discharges are ignited in cylindrical quartz tubes with interelectrode gaps of 10 and 6 cm. Helium and neon are found to be the most effective buffer gases. The optimum partial pressures of the light inert gases and iodine vapor in the glow discharge are within 0.4–0.6 kPa and 100–150 Pa, respectively. In the capacitive discharge in He(Ne)-I₂ mixtures, the optimum partial helium, neon, and iodine vapor pressures are within 0.8–2.0 kPa, 0.5–1.0 kPa, and ≤ 60 Pa, respectively. It is demonstrated that pulsed bactericidal radiation sources with light pulse lengths of 400–500 ns and continuous radiation sources emitting within the spectral range 150–207 nm can be designed on the basis of low-density iodine vapor plasma.     

Low-Noise single-frequency He-Ne laser with stable output power at a wavelength of 1.52 µm

The results of investigation of the energy and spectral characteristics of a He-Ne laser (λ_rad=1.52 μm) with transverse microwave discharge are presented. A single-frequency generation mode at a pressure above 6.0 mm Hg was obtained with radiation power 7.0 mW and low level of amplitude noise (10⁻⁵ Hz^−1/2). Active stabilization of the laser power was carried out, which allows reduction in radiation intensity fluctuations from 1–5 to 0.1 %. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 127–128, January–February, 2000.     

Continuous frequency up-conversion in a double-Λ scheme of Na2

 In a double-Λ level configuration of Na₂ molecules, involving rotational–vibrational levels of the X, A and B bands, continuous resonant frequency mixing ω₄=ω₁−ω₂+ω₃ is demonstrated. A DCM dye laser at 661 nm (λ₁) pumps a molecular Raman laser at 746 nm (λ₂) in a sodium heatpipe, which is used to generate the molecular vapour. In the same heatpipe, both fields are mixed with the radiation of an argon-ion laser at 514 nm (λ₃) to generate up-converted laser radiation at 473 nm (λ₄). For laser powers of 200 mW (λ₁), 700 mW (λ₂, internal power) and 140 mW (λ₃), an output power of 120 μW (λ₄) has been achieved. Dependences of the generated radiation on the pump fields (powers and detunings) and polarization features are presented; influences of coherent coupling and population transfer mechanisms are discussed. Received: 7 October 1996