Lasers in cardiosurgery: History, problems, promises

This paper gives a retrospective overview of the use of lasers in cardiosurgery and primarily, in laser angioplasty. Despite the spotty character of interest in this problem, the latter has been shown to be still urgent, and the technical approaches found in recent years open up new avenues in this field. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Research Institute of Cardiology, RAMS (Tomsk Scientific Center). Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 73–75, April, 2000.     

Formation and development of laser physics at Tomsk University

The formation of the laser school in the Siberian Physical-Technical Institute at Tomsk State University is considered in historical perspective. The most important achievements and publications are discussed. The role of Siberian Conferences on Spectroscopy held regularly under the supervision of Prof. N.A. Prilezhaeva in the development of laser physics at Tomsk University and in the city of Tomsk is demonstrated. Tomsk State University; the V. D. Kuznetsov Siberian Physical-Technical Institute at Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 4–13, August 1999.     

Investigation of mode coupling in a multimode superconducting cavity to store and extract UHF energy

Nuclear Physics Scientific Research Institute, Tomsk Polytechnical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 7, pp. 868–875, July, 1990.     

Relationship between dielectric strength and the multifractal nature of charge distribution on the surface of an electrode

A study is made of the manner in which the nonuniformity of the charge distribution on the surface of an electrode affects the dependence of mean breakdown lag time on electrode area.Scientific Research Institute for High Voltage, Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 96–99, November, 1993.     

Pulsed breakdown voltages of supercooled rubbers

We present the results of pulsed breakdown voltage experiments on supercooled rubber as a function of sample cooling time and thickness. We also present the volt-second characteristics of rubber and liquid nitrogen. We recommend a method for electric pulse fracturing of supercooled rubbers. High Voltage Scientific Research Institute, Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 86–90, August, 1997.     

Formation of ultrashort microwave pulses in coaxial cavities

We describe shaper cavities for the production of ultrashort microwave pulses with a minimum duration of one period of the high-frequency field and a power of several tens of megawatts. Experimental results are presented.Scientific and Research Insititute for Nuclear Physics at S. M. Kirov Polytechnical Institute, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 12, pp. 1250–1256, December, 1995.     

Radiation of a flow of oscillating electrons in the excitation of parametric oscillations

A study is made of phase modulation of an electron flow and the saturation of coherent radiation in such a flow after parametric excitation in a nonlinear system. Expressions are obtained for the intensity of the radiation of a charged particle and the coherent radiation in a resonator. The dependece of the intensity and frequency of the radiation on the amplitude and frequency of the external source are examined. Scientific Research Institute of Nuclear Physics at Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 103–106, October, 1997.     

Mathematical modeling of nonstationary thermophysical processes in spacecraft onboard-apparatus bays

Propagation of heat due to heat conduction and operation of the low-temperature heat pipes in the structural elements of spacecraft are modeled numerically. The multidimensional nonstationary temperature fields in honeycombed panels with spatially distributed and locally concentrated heat sources were calculated.Scientific-Research Institute of Applied Mathematics and Mechanics at Tomsk State University. Scientific and Industrial Association of Applied Mechanics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 119–128, April, 1993.     

Pseudospark switches for the power supply circuits of pulsed lasers

A family of sealed-off low-pressure spark gap switches developed at the Institute of High Current Electronics (Tomsk) and at the Plasma Scientific Research Institute (Ryazan) with participation of researchers from the Physical Institute of the University of Erlangen (Germany) is described. The devices are of cermet construction, are capable of switching pulsed currents over wide ranges of amplitudes and durations, and have a number of unique characteristics. The principle of operation of the spark gap switches is described and their designs are given. The triggering circuits of the switches are considered. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Plazma Scientific Research Institute of Gas-Discharge Devices. Physical Institute of the University of Erlangen. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 97–105, April, 2000.     

Autoelectronic emission of metallic films induced by picosecond pulses of infrared laser radiation

The well-known defects of the surface of a solid, microscopic projections and spikes, play a decisive role in electron emission induced by an electric field. If there are mobile electrons of holes in the solid, then the electric field is enhanced by a factor of 10–100 at the tip of a microscopic projection. This effect was discovered in electrostatics more than a century ago. In turn, the probability of tunnel emission of an electron from a metal into a vacuum is an exponential function of the electric field strength. Correspondingly the electron emission current density at the tip of a microscopic spike can be larger than that on a smooth surface by an astronomical factor. This effect is particularly strikingly manifested when picosecond pulses of infrared laser radiation of moderate power are used to initiate autoelectronic emission. Relative to a smooth surface, the emission current density is enhanced by hundreds of orders of magnitude. These experimental conditions can be used to scan the surface of a conducting material with a laser beam and to detect all the microscopic projections, in order to male detailed observations with subpicosecond time resolution of the phase transition from autoelectronic emission to explosive emission. Polytechnic University, Tomsk. Institute of Electrophysics, Ural Branch of the Russian Academy of Sciences. French National Scientific Center, Saclay, France. Translated from Izvestiya Vysshikh Uchenbnykh Zavedenii, Fizika, No. 11, pp. 42–44, November, 1997.     

Deflection of an electron beam with a 1.8-MeV energy incident at glancing angles on a dielectric surface

The first results of investigations into the effect of self-deviation of an electron beam with intermediate energy by a dielectric surface, previously discovered by the authors for the interaction of electrons with a glass surface, are presented in the paper. It is shown that optimizing the deflection process and choosing a dielectric target, angles of beam deflection of the order of 5–8° can be obtained and stabilized during subsequent irradiation of the target, which is especially important for applications of this effect to electron-beam optics. Scientific Research Institute of Nuclear Physics at Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 12–17, September, 1999.     

The conductivity of aluminum nitride ceramics

Based on the analysis of the experimental behavior of the conductivity of highly dispersed aluminum nitride ceramics on temperature and frequency, conclusions are drawn about the existence in polycrystalline AIN of electromigration hopping mechanisms. At low temperatures and for high frequencies, the conductivity can be described within the framework of a two-point model, but as the temperature increases, or as the frequency decreases, a transition is observed through multiple jumps. The electromigration activation mechanisms dominate at temperatures higher than 370 K.Scientific Research Institute on High Voltages, Polytechnical University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 122–14, July, 1992.     

Structural and phase transformations in Ni3Fe during high-dose ion implantation

The results are given for experimental studies of the structural-phase state formed in the surface and nearsurface layers of a disordered polycrystalline Ni₃Fe alloy during high-dose ion implantation. The studies used Auger electron spectroscopy, transmission electron microscopy, x-ray structural analysis, and microhardness measurements. The ion implantation was done using the “Raduga” vacuum arc source with a multicomponent cathode of composition Zr (89.5 wt. %)+C+N+O with an acceleration voltage of 50 kV. The implanted ion dose was varied in the range (6.0·10¹⁶–6.0·10¹⁷) ions/cm². It was established that in the surface layer which is alloyed during ion implantation there is amorphization with simulataneous formation of finely dispersed ZrO₂ particles whose dimensions increase with increasing implanted ion dose; this is accompanied by an increased internal mechanical stress. Beyond the ion-implanted layer a sublayer about 10 μm thick with a high dislocation density is formed (the “long-range action” effect). The results of microhardness measurements correlate with the data from structural studies. Institute of the Physics of Strength and Materials Science, Siberian Section, Russian Academy of Science; Tomsk State University—Architectural-Construction University; and Scientific Research Institute for Nuclear Physics at Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 15–24, November, 1998.     

Advances and breakthroughs in metal vapor lasers

Self-terminating metal-vapor laser research and development work performed under the supervision of the author is reviewed. Primary attention is given to lasers with output parameters controlled through the electron component of the repetitively pulsed discharge. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 23–36, August, 1999.     

Relation between the distribution of initiation sites of a discharge and the field nonuniformity at an electrode

The connection between the field nonuniformity at an electrode and the distribution of discharge initiation sites over its surface is described. The results of experiments on the breakdown of transformer oil in the cone-plane system of electrodes is analyzed within the framework of a multifractal model of the charge distribution [1]. The conclusion given in [1] that the regions with the maximum local field strength are not always the most probable sites for initiation of a discharge was experimentally confirmed. We observed the theoretically predicted transition of the discharge initiation sites at sharp points on the surface of a cone. For electrodes of stainless steel and transformer oil a value of the index relates the probability of initiation of a discharge to the local field strength was determined.Scientific — Research Institute of High Voltages at Tomsk Polytechnic Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 32–35, April, 1995.     

Initiation of heterogeneous photocondensation processes by laser radiation

A physical model of heterogeneous photocondensation processes initiated in a saturated-vapor atmosphere by intense laser radiation is proposed. Several mechanisms of induction of nonlinear supersaturation in the medium are examined. The concentration and maximum radius of the formed drops for a prescribed nonlinear supersaturation are calculated. It is shown that the laser-flash energy introduced initially into the medium and ensuring the transfer of the condensation nuclei across the forbidden radius gap is capable of initiating a much more energetic macroprocess of drop generation from supersaturated vapor.Part of this work was reported at the Regional Applied Science Conference, Tomsk, Oct. 27–30, 1977. Proceedings of Physicotechnical Section. Tomsk State Univ., p. 81.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 80–84, June, 1979.     

Diagnostics of nonlinearities using scattered field disturbances

We formulated an integral equation for finding the field in an arbitrary nonlinear medium. In the case of a localized nonlinearity, this equation is effectively solved using the iteration technique. It is shown that the inverse problem of recovering current-voltage characteristics of arbitrary nonlinearities by scattered field disturbances can be solved on this basis. Tomsk State University, Tomsk, Russia Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 7, pp. 645–651, July, 2000.     

Semibounded symmetry operator transformation of nonrelativistic free-particle coherent states

Coherent-state systems are considered that are obtained by applying symmetry operators to free-particle coherent states. Existence and uniqueness are proved for measures providing the expansion of a unit operator in terms of those states. Integral equations are given for determining the corresponding measures. Tomsk State University and Tomsk State Pedagogic University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. 2, pp. 12–18, February, 1999.     

Structural and electrophysical characteristics of YBCO films on sapphire

We present experimental results for the structural and electrophysical characteristics of YBCO films deposited on sapphire substrates without an interface layer. The films were deposited by laser sputtering of a target. We establish certain relationships between the structural and electrophysical characteristics of the films. We show the films’ electrophysical parameters are determined by the number of "defective" blocks whose [010] axes are at random angles relative to the [100] axis of the substrate. V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk University. Translated from Izvestiya Vysshikh Uchebnykh Zaved, Fizika, No. 5, pp. 75–78, May, 1998.