Characteristics of an electric circulation module for pulse-periodic ArF*, KrF*, and XeF* molecular lasers

The characteristics of an electric circulation module for a miniature, pulse-periodic, inert-gas fluoride laser utilizing He/(Ar, Kr, Xe)/F₂ mixtures at a pressure of 100–350 kPa have been investigated and results are presented. It is shown that a positive dc voltage is optimum for supplying the electric circulation module. The lasing zone of a negative corona discharge is of interest for developing simple high-pressure excimer lamps with a self-circulating active medium. Pis’ma Zh. Tekh. Fiz. 23, 49–55 (July 26, 1997)     

Characteristics of a submicrosecond transverse discharge in mixtures of helium with N2 and CO molecules and xenon atoms

An investigation is made of the electrical and optical characteristics of a moderate-pressure transverse discharge in typical active media of infrared CO lasers. The discharge was ignited in a system of unprofiled “ grid-plane” electrodes with automatic ultraviolet preionization by a corona discharge and had a 2×3 cm aperture. The pulse repetition frequency was 1–10 Hz, the current pulse length was ≤0.5 μs, and the pressure of the working mixtures was 10–100 kPa. Studies were made of the transverse discharge current voltage pulses, and also the spectral and temporal characteristics of the plasma radiation in N₂:CO, He:N₂:CO, and He: N₂:CO:Xe mixtures in the ultraviolet and visible ranges. Pis’ma Zh. Tekh. Fiz. 23, 71–76 (October 12, 1997)     

Characteristics of transverse volume discharge in Cf2Cl2 and in Ar/Cf2Cl2 mixture

The conditions of ignition and the characteristics are given for a nanosecond transverse volume discharge in Freon-12 (CF₂C1₂) and in an Ar/CF₂C1₂ mixture. It is shown that, in the ultraviolet and visible ultraviolet spectral region, a plasma based on CF₂C1₂ molecules is a source of radiation of excited carbon atoms and Cl₂ molecules. The volumetric stage of the discharge exists atU _charge ≤ 12 kV and [CF₂C1₂] = 0.1–3 kPa, and the current and voltage oscillograms are similar to the respective characteristics of a transverse discharge with prior-to-prebreakdown electron multiplication in He(Ne)/SF6(F2) mixtures. A plasma of an Ar/CF2C12 mixture is a source of radiation of the λ = 258 nm bands for Cl ₂ ^* , 193 nm for ArF, and 175 nm for ArCl. Such sources may be used in short-wave pulse photometry, microelectronics, and photo- and biochemistry.     

A planar excimer-halogen radiation source pumped by transverse RF discharge

We present the characteristics of a planar source of wideband shortwave radiation pumped by transverse RF (f=1.76 MHz) discharge in a Kr/Xe/Cl₂ mixture (P≤500 Pa). The spectral characteristics of the plasma emission were studied in the wavelength interval of 130–600 nm. The oscillograms of the voltage, current, and output radiation intensity and the diagrams of the output power depending on the gas pressure, partial composition of the working gas mixture, and discharge power are presented. It is established that the source produces emission predominantly in the spectral interval of 170–330 nm, representing a system of the molecular emission bands XeCl(D, B-X), KrCl(B-X), Cl₂(D′-A′), and Cl₂**. For a maximum output power in the UV-VUV range, the optimum working gas mixture is Kr/Xe/Cl₂ with the partial pressures P(Kr)/P(Xe)/P(Cl₂)=150–200/150–200/20–40 Pa. The maximum power irradiated within a solid angle of 4π via two output holes with a total area of S≤ 100 cm² reaches 30–40 W. In the region of a threshold with respect to the transverse discharge initiation, there are narrow peaks of plasma emission that are probably related to the jumps in the density of electrons and the positive and negative ions at the boundary between the plasma and the RF discharge layer.     

Excitation of low-frequency oscillations on water surface in electrostatic field

The behavior of a dielectric liquid in the interelectrode gap with an electric charge induced on one of the two electrodes has been experimentally studied. The effect of an electrostatic field on the immobile water surface has been determined for an applied voltage within 1000 V ≤ U ≤ 12 000 V. The formation of cone-shaped protrusions on the liquid surface is limited by plasma discharge, which induces cyclic oscillations in the liquid at a constant frequency f. A further increase in the applied potential leads to stepwise changes in the oscillation frequency. Initial variation of the potential within 500–900 V is not accompanied by any significant change in f, but the subsequent increase in U within a narrow interval (20–40 V) leads to a resonant change in the oscillation frequency.     

A pulsed-periodic low-pressure volume discharge in a krypton-chlorine gas mixture

The initiation conditions and characteristics of a volume discharge in a krypton-chlorine mixture at low pressures (P≤1.0 kPa) were studied. It is shown that a constant voltage of U _ch 1.0 kV applied to a spherical anode-flat cathode system gives rise to a pulsed-periodic discharge with a pulse repetition rate of 1–50 kHz. The current-voltage characteristics of the discharge, the spectra of emission in a wavelength interval of Δ λ=130–350 nm, and oscillograms of the current and the total output emission intensity were studied as dependent on the partial composition and pressure of the krypton-chlorine mixture. It is shown that the discharge is a selective source of emission in the electronic-vibrational bands with λ=257 nm [Cl₂(D′-A′)], 222 nm [KrCl(B-X)], and 200 nm [C1₂**]. The volume discharge in the Kr-Cl₂ mixture can be used for the development of pulsed-periodic low-pressure excimer-halogen lamps.     

Estimating the energy of electric breakdown in air gap between electrolyte and metal electrode

The influence of induced electric charge (localized on the surface of a suspended copper rod) on the formation of a protrusion (Taylor cone) on the inducing liquid (aqueous solution) surface is considered. At an applied voltage of U ≤ 12 kV, the protrusion height in the interval of pre-breakdown voltages (U < U _P) is limited by the electric field strength. At U > U _P, the growth of protrusion is terminated by an electric discharge, which drives the liquid to oscillate in a broad range of applied voltages U at almost constant multiple frequencies f = f ₀ n, which are resonantly switched at certain fixed U values. By measuring the amount of evaporated liquid, the energy (27.8 × 10⁻³ J) and current (64.9 A) of single discharge were evaluated and the electric capacitance (7.6 × 10⁻¹⁰ F) of a system comprising the water surface and suspended copper electrode was estimated. Serial connection of an additional capacitor (100 μF) to the copper electrode with induced electric charge leads to a threefold increase in these parameters.     

Atomic near-infrared noble gas scintillations I: Optical spectra

Particle beam excited emission spectra from Ne, Ar, Kr and Xe in the wavelength range 350–930 nm and in the pressure range 20–200 kPa are studied. Ar, Kr and Xe show dominant emission from neutral atoms in the near-infrared region. For Ne this emission extends from the visible to the near-infrared region.To study the emission spectra of electrostatic field enhanced scintillations a wire was inserted into the chamber and spectra from Ne, Ar, Kr and Xe were recorded with positive and negative wire potentials. The same dominant emission from neutral atoms is present in these spectra. Due to contamination of N₂ in the Ne gas strong emission of N₂ bands are seen in the electrostatic field enhanced scintillation Ne spectra.     

Characteristics and plasma parameters of a short-wavelength low-pressure discharge lamp

We have studied the working optical characteristics and electron kinetic coefficients of a short-wavelength, electric discharge exciplex-halogen UV-VUV lamp employing a mixture of argon and chlorine with a total pressure of P = 0.5–10 kPa. The lamp operates on a system of broadened electron-vibrational bands of ArCl (175 nm) and chlorine (200, 258 nm) molecules, which overlap to form a continuum in the spectral range of 160–260 nm. It is established that the optimum mixtures are those with p(Ar) − p(Cl₂) = (2–4)−(0.15–0.30) kPa. The average output power of the short-wavelength radiation is 1–2 W at an efficiency of ∼5%. The electron energy distribution functions (EDFs) and the discharge plasma parameters have been calculated by solving the Boltzmann equation for a gas mixture with the experimentally determined optimum composition in the range of E/P values from 1 to 200 V/(cm Torr), where E is the electric field strength and P is the total gas pressure. Using the obtained EDFs, the electron transport characteristics, specific discharge power losses for the main elementary processes, and rate constants of electron processes are determined.     

Impedance studies of polycrystalline tin oxide

Polycrystalline SnO₂ samples prepared in the laboratory were irradiated with 2 MeV He ions having doses of 3.62 × 10¹⁵ ion/cm². The ac small-signal electrical data acquired for the polycrystalline SnO₂ in the frequency (f) range 100 Hz ≤ f ≤ 1 MHz and temperature (T) range 26°C ≤ T ≤ 100°C revealed one semicircular relaxation in the impedance plane for the He implanted sample. However, two semicircular relaxations were obtained in the same plane for the samples without He implantation. The He implantation indicated enhancement in the donor density in the polycrystalline SnO₂ as depicted via terminal conductance (or resistance). An erratum to this article can be found at     

Using open atmospheric electric discharge for water purification from surface contamination with oil products

The characteristics of open atmospheric dc discharge between a liquid nonmetal cathode (tap water layer) and a metal anode have been studied. The effect of discharge on a layer of oil products (diesel fuel, lubricant oils) contaminating the liquid cathode surface was determined. The discharge current-voltage characteristics and the dependence of the cathode current density on the discharge current I were measured in the interval 20 mA ≤ I ≤ 300 mA for the discharge gap width varied within h = 2–10 mm. For h ≥ 4 mm and I ≥ 120 mA, the cathode current density and the interelectrode voltage are independent of the discharge current, which is characteristic of the normal glow discharge. Under the action of discharge, oil products in the contamination layer on the liquid cathode surface are partly decomposed and partly converted, after which the conversion products can be readily removed from the surface by mechanical methods. The efficiency of contaminant removal can reach 98%. Analysis of the conversion products showed that they are composed of polymer chains with variable length and structure involving oxygen-containing groups.     

Getter pumping to allow economical sputtering with xenon

Increases in sputter rate, under equivalent commercial operating conditions, can often be achieved by using inert gases heavier than Ar. High atomic weight targets and high sputter voltages result in Kr and Xe having higher sputter yields than Ar. The larger ionization cross sections of Kr and Xe also result in a plasma enhancement. The high consumption rate of sputter gas has previously prevented the economical utilization of Kr and Xe. A d.c.-powered Ti sputter target was added to an r.f. planar diode sputtering system. The sputtered titanium was deposited directly on the vacuum chamber walls to form a large room temperature getter pumping surface. Calculations showed an increase of two orders of magnitude in the pumping speeds of O₂, N₂, H₂O and H₂ over that of a conventional throttled 10 cm diffusion pump. This pumping speed allowed improved sputter cleaning of substrates and the deposition of higher purity films. Operating the Ti getter pump with the diffusion pump closed allowed sputtering with very little inert gas consumption. R.f. sputtering of a Ti target with 750 W at 8 mTorr gas pressure resulted in a sputter gas consumption rate of 3 × 10^-3 cm³ min^-1 for both Ar and Xe. This consumption rate corresponds to a Xe cost of less than 1 ¢ h^-1.     

Electrical and Magnetic Properties of Zr4+ and Ni2+ Ions Substituted Mn–Cu Spinel Ferrites

The Mn–Cu nanoferrites of composition Mn_0.5Cu_0.5Fe_2−2x Ni _x Zr _x O₄ (0.00≤x≤0.80) were synthesized by incorporating dopant Zr⁴⁺ and Ni²⁺ cations via a chemical coprecipitation technique. The single phase of the prepared spinel nanoferrites with particle sizes 15–31 nm was confirmed by XRD. Both electrical and magnetic properties are found to depend on the x contents and explained by considering the Zr⁴⁺ and Ni²⁺ cations distribution, displacement of the Fe³⁺ ions by dopants, changes in magnetic moment at tetrahedral A site and octahedral B site, Fe³⁺(A)–O₂–Fe³⁺ [B] linkages and extent of the primary superexchange interactions (A)–O–[B] of the Fe³⁺ ions on the A and B-sites. DC resistivity, saturation magnetization (M _s), remanence (M _r) and Bohr magneton (n _B) are observed to increase up to x≤0.40, while these parameters fall at relatively higher value of x≥0.60.     

Orientation and temperature dependence of superelasticity caused by reversible γ-α′ martensitic transformations in FeNiCoAlTa single crystals

Reversible thermoelastic γ-α′ martensite transformations (MTs) have been studied in Fe-28%Ni-17%Co-11.5%Al-2.5%Ta (at. %) single crystals under cooling/heating and loading conditions. It is established that the precipitation of dispersed γ′ phase particles with an average size of d ≤ 5 nm leads to thermoelastic γ-α′ MTs with a small temperature hysteresis (ΔT = 20 K). The [001] oriented crystals favor the attaining of maximum superelasticity (SE) ɛ_SE = 6.8%, minimum mechanical hysteresis Δσ = 130 MPa, and large SE temperature interval ΔT _SE = 130 K. In contrast, in the [111] oriented crystals, small values of ɛ_SE = 2.0%, high values of Δσ = 350–400 MPa and narrow SE interval ΔT _SE = 55 K are found.     

Molecular Dynamics Study on the Anisotropic Thermal Conductivity of Helium–Xenon Binary Nanocrystal Superlattices

The anisotropic thermal conductivity of helium–xenon binary nanocrystal superlattices (BNSLs), which are stoichiometric solid structures Xe(He)₂ and Xe(He)₁₃, at high pressure and room temperature (T = 300 K), respectively, has been calculated by equilibrium molecular dynamics (EMD) simulation using the Green–Kubo formalism and the exponential-6 intermolecular potential under periodic boundary conditions (PBC). The pressures obtained from EMD agree very well with those from an independent study, to within 5 %. Nonequilibrium molecular dynamics (NEMD) simulation is also carried out for comparison. The thermal conductivities predicted by NEMD are of the same order of magnitude as the results predicted by EMD. The anisotropic thermal conductivities of stoichiometric solid structures (Xe(He)₂ and Xe(He)₁₃) with different molar volume and atomic number are investigated, and results show that the thermal conductivities of Xe(He)₂ are more strongly anisotropic than those of Xe(He)₁₃, whereas the averaged thermal conductivities of Xe(He)₂ are around one tenth (1/10) of those of Xe(He)₁₃, indicating that the thermal conductivities of helium–xenon BNSLs (Xe(He)₂ and Xe(He)₁₃) significantly depend on the molecular structure in both magnitude and anisotropy. The results also show that both the magnitude and anisotropy of the thermal conductivity of helium–xenon BNSLs (Xe(He)₂ and Xe(He)₁₃) slightly depend on the atomic number and molar volume of the simulation system, with finite-size effects existing in the nanoscale system.     

Emissive characteristics of mesa-stripe lasers (λ=3.0–3.6 μm) made from InGaAsSb/InAsSbP double heterostructures

The directional patterns, current-voltage characteristics, and spectral characteristics of mesastripe lasers with InGaAsSb active layers, emitting at λ=3.0–3.6 μm (77 K) and having threshold currents ≥15 mA (j _th≥200 A/cm²), are investigated. The maximum output power is 1.4 mW (λ∼3.3 μm), the differential quantum efficiency ∼3%(τ=5–30 μs, f=500 Hz) for lasing in a longitudinal mode with beam divergences ΔΘ∥∼15° and ΔΘ ⊥ ∼30°. The relationship of the differential quantum efficiency to the order of the spatial mode of the lasing is demonstrated. A single-mode, current-tunable (−30 cm⁻¹/A) laser is used to measure the transmission of methane in the region of the ν ₃ absorption band. Pis’ma Zh. Tekh. Fiz. 24, 40–45 (June 26, 1998)     

Determination of the content of <Superscript>85</Superscript>Kr and <Superscript>133</Superscript>Xe in air using a krypton-xenon mixture

A procedure was developed for determining radioactive isotopes of Kr and Xe in air using a krypton-xenon mixture (KXM) produced at air separation plants. The procedure allows determination of background volume concentrations of Kr and Xe at long distances from sites of their injection using common spectrometric apparatus. The results of monitoring volume concentrations of ⁸⁵Kr and ¹³³Xe in Cherepovets in 2006–2008 are presented.     

Adiabatic compressibility of solid gases

Adiabatic compressibilities of solidCO (20–67 K) and NH₃ and ND₃ (90–190 K) have been determined with an ultrasonic method. The temperature dependence of adiabatic compressibility is discussed for two groups of molecular crystals: solid inert gases (Ar, Kr, Xe, Ne) and a number of simple molecular crystals with nonspherical particles (CO, CO₂, NH₃, ND₃). The effect of orientational disordering processes on molecular crystal compressibilities has been considered.     

The formation of excited chlorine atoms in a low-pressure transverse volume discharge

The characteristics of a transverse volume discharge (TVD) in chlorine at low pressures (P(Cl₂)=0.1–1.5 kPa) were studied. The excited chlorine atoms were formed in a 18×2.2× (0.5–1.0) cm volume using relatively low values of the capacitor bank charging voltage (U _ch ≤ 10 kV) in the pulsed discharge voltage source. The optical emission from plasma was studied in a spectral range from 500 to 900 nm. Homogeneous TVD pulses of short duration (τ; ≤ 100 ns) obtained under these conditions are of interest for use in UV-VUV lamps employed in pulsed plasmachemical reactors for dry etching of thin films. The density of excited atomic chlorine radicals can be monitored on medium-resolution spectrometers using the ClI emission lines with λ=725, 754, and 821 (2) nm.     

The solubility of inert gases in liquid-metal heat-transfer agents

In the case of neutron irradiation of some metals, many of the nuclear reactions (n, p), (n, α), and (n, 2n) lead to the formation of inert gases [1]. The formation of isotopes of helium in these reactions, as well as of isotopes of xenon¹³³Xe and krypton⁸⁵Kr, as the products of fission of fuel in fast neutron reactors has a considerable effect on the heat-transfer and hydrodynamic characteristics of the heat-transfer agents (for example, alkali metals and alloys on their basis), this necessitating the investigation of the solubility of inert gases in liquid metals [2]. In addition, note the considerable effect of dissolved inert gases on the thermal properties of liquid metals at high temperatures, especially, in the critical point region. The paper presents the results of calculation of the solubility of inert gases (helium, argon, krypton, xenon) in liquid alkali metals atT=600 K andP = 0.1MPa.