A Pulsed-Periodic, Low-Pressure Volume Discharge in Chlorine and in a Xenon/Chlorine Mixture

The electrical and optical characteristics of a self-initiated, low-pressure, pulsed-periodic discharge in chlorine and in a xenon/chlorine mixture are investigated. A volume discharge not bounded by dielectric walls was triggered in a spherical anode–plane cathode system of electrodes on supply of a constant positive-polarity voltage to the anode. The discharge existed in the form of a unit domain. The spatial, spectral (in the range 150–350 nm), and time characteristics (voltage, current, and photocurrent of total radiation of plasma in the spectral range 200–700 nm) of the volume discharge are investigated. Optimization of the pressure and of the structure of the working medium is carried out to obtain the maximum brightness of UV–VUV radiation of the bands of the Cl₂(D–A), Cl₂ ^**, and XeCl(D, B–X) molecules. The results obtained are of interest for being used in a pulsed-periodic, excimer-halogen low-pressure lamp.     

Production of a large-volume plasma by a hot-cathode arc

Probe measurements reveal that the plasma produced by a hot-cathode arc contains two groups of electrons, with temperatures 4 and 10 eV, with a density of 10¹⁰–10¹¹ cm^–3. These electrons are distributed uniformly over a volume of 0.2 m³. The discharge voltage is found as a function of the gas pressure and the heater current. Low-temperature regimes of the deposition of TiN coatings on metals and insulators after a plasma processing of the articles are described. The design of the discharge system is discussed.Institute of High-Current Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 115–120, March, 1994.     

Reflection of narrow light beams by a scattering medium

A calculation is made of the doubly back scattered radiation from the intersection volume and the close-range volume. A comparison of the results for singly and doubly scattered radiation with experimental data enables the limits of applicability of the equations to be determined. It is shown that for scattering coefficients in fog of < 0.06 m^–1 the scattered radiation field is caused by single scattering but when increases to 0.6 m^–1 only the doubly scattered radiation from the intersection and close-range volumes need be considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 95–100, April, 1974.     

Scaling and performance of CO2 lasers at supra-atmospheric pressure

The performance of a compact uv photo-preionized TE laser is studied in the pressure range 1–5 bar. As the pressure is increased, the laser pulse shape is little altered, but both the peak power and the total output pulse energy increase significantly with pressure, even for constant input electrical energy. For various gas mixtures and excitation source capacitors the measurements suggest approximate output energy scaling with the product of the source charge per unit electrode area [C.m^–2] and the molecular partial pressure [CO₂+N₂+CO]. This is explained in terms of the pressure-dependent discharge impedance. An input-energy-related discharge instability limits the optimum laser pressure to 1.5–2.5 bar, and we show that, at constant input energy, the instability boundary depends on the molecular partial pressure alone. The pre-ionization photo-electron yield varies negligibly with pressure, but the discharge tolerance to added oxygen decreases asp ^–3 top ^–4, dependent on gas mixture. Nevertheless sealed operation for >10⁵ shots has been obtained with a 5% CO₂5% CO3% N₂2% H₂85% He gas mixture at a total pressure of 5 bar.     

The role of dislocations in radiation strenghtening of alkali halide crystals

The dependence of activation volume and dislocation start stress in sodium and calcium chloride crystals on-radiation dosage (in the range 10⁴–10⁹rad) is studied. It is established that these functions indicate that the hardening of crystals subjected to radiation is of a dislocation nature. Analysis of data from the literature leads to the conclusion that in the medium and high radiation dose region planar precipitates and surrounding dislocations formed by halogen molecules are responsible for hardening.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 99–103, June, 1976.     

Effect of the Radiation Power Density on the Sensitivity of a Diamond Detector

This paper presents the results of an experimental study of the sensitivity of a detector made of natural diamond of the IIa type as a function of the power density of the radiation of a pulsed xenon lamp. It has been shown that the sensitivity of the detector depends on the power density of the xenon lamp radiation and equals about (1–6)·10^–4 A/W. A monotonic decrease in sensitivity of the detector during a radiation pulse has been detected. The minimum resistance of the diamond crystal with an irradiated face of area 3 mm², placed 7 mm away from the axis of the xenon lamp, was 300 , which corresponds to a specific conductivity of 2.2 ^–1·m^–1.     

Orthogonality and Boundary Conditions in Quantum Mechanics

One-dimensional particle states are constructed according to orthogonality conditions, without requiring boundary conditions. Free particle states are constructed using Dirac's delta function orthogonality conditions. The states (doublets) depend on two quantum numbers: energy and parity (+ or —). With the aid of projection operators the particles are confined to a constrained region, in a way similar to the action of an infinite well potential. From the resulting overcomplete basis, only the mutually orthogonal states are selected. Four solutions are found, corresponding to different non-commuting Hamiltonians. Their energy eigenstates are labeled with the main quantum number n and parity + or —. The energy eigenvalues are functions of n only. The four cases correspond to different boundary conditions: (I) The wave function vanishes on the boundary (energy levels: l⁺,2^–,3⁺,4^–,...), (II) the derivative of the wavefunction vanishes on the boundary (energy levels 0⁺,l^–,2⁺,3^–,...), (III) periodic boundary conditions (energy levels: 0⁺,2⁺,2^–,4⁺,4^–6⁺,6^–,...), (IV) periodic boundary conditions (energy levels: l⁺,1^–,3⁺,3^–,5⁺,5^–,...). Among the four cases, only solution (III) forms a complete basis in the sense that any function in the constrained region, can be expanded with it. By extending the boundaries of the constrained region to infinity, only solution (III) converges uniformly to the free particle states. Orthogonality seems to be a more basic requirement than boundary conditions. By using projection operators, confinement of the particle to a definite region can be achieved in a conceptually simple and unambiguous way, and physical operators can be written so that they act only in the confined region.     

Hollow-Cathode Low-Pressure Arc Discharges and Their Application in Plasma Generators and Charged-Particle Sources

This paper presents the results of a study of hollow-cathode arc discharges which generate gas-discharge plasmas of densities 10¹⁰–10¹² cm^–3 in large volumes (1 m³) at low pressures (10^–2–1 Pa) and at discharge currents of up to 200 A. Consideration is given to the design and peculiarities of hot-cathode and cold-cathode discharge systems. The parameters of plasma generators and charged-particle sources where use is made of arc discharges are cited and the problems of the most efficient application of such systems in technological processes of solid surface modification are discussed.     

Generation of picosecond pulses in solid-state lasers using new active media

Results are reported of investigations aimed at generating nanosecond radiation pulses in solid-state lasers using new active media having broad gain lines. Passive mode locking is accomplished for the first time in a BeLa:Nd³⁺ laser at a wavelength 1.354 m, and in a YAG:Nd³⁺ laser on a 1.32–m transition. The free lasing and mode-locking regimes were investigated in an alexandrite (BeAl²O₄:Cr³⁺) laser in the 0.72–0.78–m range and in a synchronously pumped laser on F 2- centers in LiF in the 1.12–1.24–m region. The features of nonlinear perception of IR radiation by the eye, using a developed picosecond laser on F₂ ^– centers, are investigated for the first time.Translated from Lazernye Sistemy, pp. 67–86, 1982.     

Radiation of the Plasma of a Transverse Discharge in a Helium–Krypton–Elegas Mixture

We carried out a spectroscopic investigation of the degradation of the active medium of a pulsed-periodic KrF emitter based on a He/Kr/SF₆ mixture (P = 10–150 kPa) with pumping by a transverse volumetric discharge. The plasma radiation spectra in the range 200–620 nm at different stages of degradation of the working mixture and the dynamics of the radiation of inert gases as well as of the products of decomposition of SF₆ molecules in the plasma are studied. It is shown that since the number of discharge pulses is 10⁴, rather effective formation of excited sulfur molecules is observed which decompose with emission in the spectral range 260–550 nm. This can be employed for developing a wideband lamp based on the system of KrF(B–X; D–X), S₂(B–X), and S₂(f–a) bands.     

Impulsive-discharge formation in water

This paper reports on research on an impulsive electrical discharge in deionized water (=2 × 10⁴ · m) in the voltage range 17–50 kV. The research showed that the discharge proceeds through the development of subsonic (U=17–22 kV) or supersonic (U=25–50 kV) streamers, depending on the electric-field strength at the surface of the tip. When voltage impulses having an amplitude of 20–25 kV are unleashed, the development of both types of streamers is observed in the discharge gap. The experiments carried out by the authors do not confirm the hydrodynamic origin of the disturbances at the initiating electrode that give rise to the discharge's development. The authors hypothesize that streamer development is due to the ionization of water molecules. The energy expenditures to ionize the molecules in the streamer channel are estimated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 88–92, January, 1989.     

Intensity distribution in the rotational structure of the electron-vibrational bands of nitrogen

The intensity distribution was measured for the rotational lines of the N₂ molecule in the radiation of a glow discharge in the pure gas, at pressure 0.1–5 torr, or with argon, at a total pressure of 2 torr, at a current of 40 mA. The distribution found lags behind a Boltzmann distribution in the 0–3 band (corresponding to the C³-B³ transition; the second positive system) over the pressure range 0.1–2 torr and in the 1–4 band (the C³-B³ transition; second positive system) at a pressure of 0.1 torr. In the N₂ + Ar mixture there is selective amplification of the J=25, 26 rotational lines.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 17–21, September, 1970.     

Special features of the operation of an electron-ionization CO2-laser at high pressures

A study was made of the excitation of the working medium of a CO₂-laser at a pressure of up to 8 atm by an electron beam of duration 15 · 10^–9 sec. Results are given of the energy dissipation in a CO₂:N₂-13 gas medium in the whole range of pressures with E₀/p = (18–38) V /cm · mm Hg. The dependences of the time of appearance of the stimulated radiation with respect to the current pulse are given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 40–44, April, 1976.     

Emission of Concentrated Solutions of Organic Compounds Excited with High-Power Laser Radiation

Specific features of emission of concentrated (C 1.2·10¹⁹ cm^–3) solutions of organic molecules (rhodamine 6G, rhodamine C, phenalemine 512, and substituted paraterphenyl (LOC-1)) are investigated as functions of the exciting photon energy (at _exc = 308 and 532 nm) and power density of exciting radiation (up to 1 GW/cm²). One of the observed emission types – band emission – is studied. The intensity of band emission (its short- and long-wavelength maxima) is investigated versus the exciting radiation power density, and its time and polarization characteristics are also analyzed. The results obtained together with the specific features of the emission spectrum of concentrated rhodamine-C solution, measured after passage of sounding radiation with maximum at the wavelength equal to that of the short-wavelength maximum of band emission, demonstrate that the band emission is simply superfluorescence.     

A Compact Pulsed HF Laser Based on an Auto-Wave Photon-Branched Chain Reaction

Huge energy gain is detected theoretically in a pulsed chemical laser-amplifier based on a photon-branched chain reaction initiating in a gaseous disperse medium composed of H₂–F₂–O₂–He and Al particles by focused external infrared radiation. It is shown that this effect is observed due to the other optical effect of diffractive multifocal focusing of the input radiation on a certain type of bicomponent optical system coupled structurally with the input mirror of an unstable telescopic laser cavity. Such a relatively simple bicomponent diffraction system, consisting of two plane screens with circular apertures on a given optical axis, enables one to focus the input beam without using classical refraction elements such as lenses and prisms. The focusing of the input signal ensures the minimization of the initially excited volume of the laser active medium and the appropriate sharp lowering of the necessary energy of the input pulse up to 10^-6 J. This enables the laser system to reach a high value of the energy gain of 10⁹. The huge laser energy gain allows us to use a master oscillator in the form of a small microjoule laser powered by an accumulator, and consequently makes it possible to construct a completely self-contained compact pulsed chemical HF-laser.     

A repetitively pulsed sealed-TE CO2 laser using an oxygen tolerant discharge scheme

A repetitively pulsed (40 Hz) TE CO₂ laser using an oxygen tolerant discharge scheme is described. Long lived (>10⁵ shots) stable discharges at high pump energy density (200 J.l^–1 atm^–1) have been achieved both with and without the use of additive gases.     

Coordinate-dependent 3+1 formulation of the general relativity equations for a perfect fluid

This paper defines mass, momentum, and energy densities for a perfect fluid, and derives a coordinate-dependent 3+1 decomposition of the equation of motion in terms of a scalar potential c ² [(–g _g44) 1/2 –1] and a vector potentialA _i cg _4i /(–g ₄₄)^1/2. The momentum equation has the form of the Euler equation except there is an additional force proportional to the vector potential and the rate of change of kinetic energy per unit volume. The momentum and energy equations are integrated to obtain the equations previously derived for a particle. The momentum equation is solved for the total acceleration of a fluid element. The equations are exact and do not depend on the choice of coordinate system.     

Field effect in CdSe single-crystal films

The surface conductivity and effective mobility were studied as functions of the surface potential on CdSe single-crystal films having a conductivity of 1–10^–5 .cm^–1. The surface potential was varied by a constant external field. The formation of a conducting channel at the film surface is governed primarily by the change in the trapping factor as volume traps near the surface are filled. Field-effect data are used to evaluate the parameters of the exponential distribution of volume traps with respect to energy, the effective concentration of small donors, and the absolute values of the surface potential.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 3, pp.43–47, March, 1971.     

On the Possible Mechanisms of Activation Changes of Enzymes under Pulsed Irradiation

Classical radiation biology, radiation treatment of patients, and pulsed radiation chemistry usually deal with weak beams of radiation and operate in terms of dose (D). In this case, only the absolute number of ionizing particles or photons interacting with the object independently of one another is important. In this work, we resume our previous investigations of enzyme activation/inactivation produced by pulsed ionizing radiation from a dense plasma focus (DPF) device at a very short and intense irradiation process, when the concentrations of spurs and blobs are sufficiently dense to allow the micro-volumes to overlap each other. The time interval is small compared with the corresponding biochemical process. It is shown that the irradiation of biological objects for a few nanoseconds by beams of x-ray photons with a low dose (D 10^-6–10^-3 Gy) but at a high dose power (D/10³–10⁵ Gy/s) may be of a collective nature and result in synergetic effects. In particular, it was found that a remarkable activation/inactivation of enzymes (horseradish peroxidase, angiotensin-converting-enzyme) takes place at low doses in these regimes. The results of irradiating the above-mentioned enzymes in vitro with x-rays of nanosecond pulse duration coming from a dense plasma focus are presented here. Neutrons (2.5 MeV, 10³–10⁵ n/cm² and x-ray photons of different energy ranges (7–9 keV and 20–200 keV) together with dose power factors are analyzed as possible reasons for the activation/inactivation of enzymes in various dose ranges. Our results are compared to those of the same experiments conducted with continuous x-ray sources based on a classical x-ray tube and on a ¹³⁷Cs-isotope source (D10^-3–10² Gy).     

Distinctive Features of the Absorption Spectra of Titanium and Iron Ions in α‐Al2O3:Ti,Fe Crystals

In the UV and visible radiation regions, the absorption spectra of Al₂O₃:Ti,Fe single crystals grown under oxidizing conditions by the Verneuil method are investigated. A considerable residual absorption in the regions 200–300 and 400–600 nm is revealed, which depends strongly on the conditions of growing (the growth rate and temperature drops) and which is caused by transitions in an impurityvacancy complex with charge transfer (IVC CT) O^2––Ti⁴⁺...Fe³⁺ and by conversion of the state of titanium ions Ti⁴⁺ Ti³⁺. The reversible conversion of the state of titanium ions Ti³⁺ Ti⁴⁺ on bending strain of specimens is established.