Dynamics of electron-cascade formation in a pulsed discharge

The dynamics of the velocity distribution function of the electrons in a pulsed discharge is analyzed, taking account of the initial stage of electron heating within the framework of the BGK model integral. It is assumed that the basic contribution to the relaxation of the electron distribution function comes from elastic collisions with neutral particles. The dynamic distribution function obtained is used to determine the ionization coefficient and study the dynamics of electron-cascade development.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 70–75, May, 1984.In conclusion, Prof. V. B. Krasovitskit must be thanked for fruitful discussion and constant interest in the work.     

Synthesis of nanoparticles using a pulsed electrical discharge in a liquid

We used a pulsed electrical discharge in a liquid to obtain Cu-, WC-, and ZnO-containing nanoparticles. The effect of the discharge current and pulse duration on the morphology and phase composition of the synthesized material was studied by spectrophotometry, transmission electron microscopy, and x-ray diffraction analysis. We discuss possible mechanisms for nanoparticle formation in a discharge submerged in a liquid. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 111–120, January–February, 2008.     

On the initial stage of a subnanosecond pulsed breakdown of high-pressure gas discharge gaps

The model of background electron multiplication is used for deriving the time dependence of ionization, which correctly describes experiments on initiation of a homogeneous high-voltage subnanosecond pulsed breakdown under a gas pressure on the order of ten atmospheres in a discharge gap ～1 mm.     

Laser-induced modification of composite Cu-C nanosized particles synthesized using a pulsed electrical discharge in a liquid

Composite copper-containing carbon nanosized structures were synthesized in the plasma of a pulsed electrical discharge, initiated between two graphite electrodes in an aqueous copper chloride solution. We studied the effect of laser radiation on the morphology of the nanoparticles formed, whose properties we studied by optical absorption spectroscopy and transmission electron microscopy. We discuss the mechanisms for nanoparticle formation in a discharge submerged in a liquid, and the possibilities for laser-induced modification of the nanoparticles. We estimated the temperature of the nanoparticles when exposed to laser radiation pulses. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 372–378, May–June, 2008.     

脉冲气体放电管特性测量实验

用TDS210型存贮示波器测量了脉冲气体放电管(闪光灯)的放电特性，同时用PIN型硅光电池测量脉冲光的波形，测量了它们之间的延迟，并计算了脉冲气体放电管的动态电阻，讨论了放电过程从触发到结束的物理图象．     

Influence of liquid resistance on the propagation rate of a pulsed discharge above it

The results of experimental and theoretical studies on the propagation rate of pulsed discharge in air at atmospheric pressure above liquids with different conductivities are presented.     

Emission characteristics of a pulsed discharge in xenon

Emission characteristics of a high-current pulsed discharge in xenon are studied experimentally. The study is aimed at developing a source of spontaneous UV radiation (with λ ≤ 250 nm) for controlling highvoltage crystalline diamond switches.     

A time-resolved study of the u-v radiation produced in the initial time period of a pulsed argon discharge

The time development of the integral intensity of ultra-violet radiation from the positive column of a pulsed discharge was studied and the results compared with those for visible light. The measurements were made at various pressures in the range 0·3–4·8 torr. We found that at a pressure about 4 torr the maxima of intensity of the u-v and the visible light occurred at nearly the same time after the initiation of the discharge. On the other hand, at a pressures of about 0·5 torr the positions of the maxima were different.     

CARS study of the vibrational kinetics of nitrogen molecules in the burning and afterglow stages of a pulsed discharge

The vibrational kinetics of the nitrogen molecule in the ground state X ¹Σ _g ⁺ in the burning and afterglow stages of a pulsed discharge are investigated by coherent anti-Stokes Raman spectroscopy (CARS). The total cross section for vibrational excitation of the nitrogen molecule by electron impact to the first eight vibrational levels is determined. The rate constant for the associative ionization reaction involving nitrogen atoms in the metastable states ² P and ² D is estimated. It is found that the best agreement between the calculated and measured populations of the nitrogen molecules in the ground state X ¹Σ _g ⁺ in the afterglow stage of a pulsed discharge is obtained when the rate constant for VV exchange K ₀₁ ¹⁰ has the value predicted by the quantum-classical Billing-Fisher model. Zh. Tekh. Fiz. 67, 34–42 (May 1997)     

Exciton absorption at the initial stages of the formation of the CuCl phase in a glass

The fundamental absorption spectra of CuCl nanocrystals in glass samples are investigated in the energy range 3–4 eV at a temperature of 300 K with the aim of elucidating the kinetics of the initial stage of the formation of the CuCl phase in the glass. The CuCl phase is grown in the glass under stepwise annealing at temperatures of 500, 615, and 707°C. The kinetics of variation in the intensity and the shift of the maximum in the exciton absorption spectra of CuCl nanocrystals are studied in the course of annealing of the glass samples. It is established that, for all the temperatures under investigation, the formation of the CuCl phase begins with the transient stage that involves the fluctuation formation of supercritical nuclei of the CuCl nanomelt. At a temperature of 500°C, the transient stage gives way to the stage of a rapid increase in the number of supercritical nuclei of the CuCl phase. At temperatures of 615 and 707°C, the transient stage gives way to the stage of an intensive growth of nuclei without a considerable increase in their number. The number of nuclei formed during the transient stage at 707°C is smaller than that observed after the transient stage at 500°C by a factor of 24. However, the sizes of the nuclei formed at 707°C are larger than those observed after the transient stage at 500°C. This difference is explained by the fact that the diffusion length of Cu⁺ ions controlling the formation of the CuCl phase increases with increasing temperature. The experimental data on the kinetics of the formation of the new phase in the glass are in good agreement with the Zel’dovich-Frenkel classical theory of the formation of a new phase, which accounts for the stage of the formation of critical nuclei.     

Spectral characteristics of a high-current pulsed discharge in xenon

The radiation characteristics of a pulsed discharge xenon lamp are experimentally and theoretically studied. The data on radiation spectra are obtained for various compositions and pressures of working medium, energies and time profiles of excitation pulse, discharge gap configurations, etc. Electron temperature and mean spectroscopic symbol of emitting ions are estimated. It is demonstrated that cw radiation (continuum) results from the photorecombination transitions.     

Producing pulsed luminescence of a high-frequency ring discharge

The results of a study of luminescence from an electrodeless high-frequency (2-Mc) ring discharge in air (0.02–10 mm Hg) are described. The discharge luminescence was pulsed. The pulse height varied within time intervals equal to the period of the external field. The qualitative effect of the constant internal electric field on pulse height is discussed.