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Lu X.,Huazhong University of Science and Technology | Naidis G.V.,RAS Joint Institute for High Temperatures | Laroussi M.,Old Dominion University | Ostrikov K.,CSIRO | Ostrikov K.,University of Sydney
Physics Reports | Year: 2014

This review focuses on one of the fundamental phenomena that occur upon application of sufficiently strong electric fields to gases, namely the formation and propagation of ionization waves-streamers. The dynamics of streamers is controlled by strongly nonlinear coupling, in localized streamer tip regions, between enhanced (due to charge separation) electric field and ionization and transport of charged species in the enhanced field. Streamers appear in nature (as initial stages of sparks and lightning, as huge structures-sprites above thunderclouds), and are also found in numerous technological applications of electrical discharges. Here we discuss the fundamental physics of the guided streamer-like structures-plasma bullets which are produced in cold atmospheric-pressure plasma jets. Plasma bullets are guided ionization waves moving in a thin column of a jet of plasma forming gases (e.g.,He or Ar) expanding into ambient air. In contrast to streamers in a free (unbounded) space that propagate in a stochastic manner and often branch, guided ionization waves are repetitive and highly-reproducible and propagate along the same path-the jet axis. This property of guided streamers, in comparison with streamers in a free space, enables many advanced time-resolved experimental studies of ionization waves with nanosecond precision. In particular, experimental studies on manipulation of streamers by external electric fields and streamer interactions are critically examined. This review also introduces the basic theories and recent advances on the experimental and computational studies of guided streamers, in particular related to the propagation dynamics of ionization waves and the various parameters of relevance to plasma streamers. This knowledge is very useful to optimize the efficacy of applications of plasma streamer discharges in various fields ranging from health care and medicine to materials science and nanotechnology. © 2014 Elsevier B.V. Source


Kanel G.I.,RAS Joint Institute for High Temperatures
International Journal of Fracture | Year: 2010

The dynamic tensile strength of materials at load durations of a few microseconds or less is studied by analyzing the spall phenomena under shock pulse loading. The paper is devoted to discussing the methodology and capabilities of the technique to measure spall strength, its error sources, spall fracture of materials of different classes and the factors governing the high-rate fracture of metals and alloys under such conditions. © 2010 Springer Science+Business Media B.V. Source


Varaksin A.Yu.,RAS Joint Institute for High Temperatures
High Temperature | Year: 2013

The problem and specific aspects of studying two-phase flows laden with solid particles, droplets, and bubbles are considered. The main characteristics of two-phase flows and methods for their modeling are reported. The results of experimental and computation-theoretical investigations of two-phase flows of different types are described. © 2013 Pleiades Publishing, Ltd. Source


Eremin A.V.,RAS Joint Institute for High Temperatures
Progress in Energy and Combustion Science | Year: 2012

This review deals with the most recent achievements in experimental investigations of the process of carbon nanoparticle formation, at pyrolysis of various carbon bearing species behind shock waves. The diverse diagnostic methods of these processes are described; special attention is given to new methods for measuring the current sizes and optical properties of particles and the temperature of the reacting mixture using time resolved laser-induced incandescence (LII), and IR emission-absorption spectroscopy. The main part of the review provides critical analysis of the numerous results of the kinetics of particle formation at various temperatures, pressures and concentrations of carbon. Particular emphasis is placed on the results obtained by pyrolysis of hydrogen free precursors. It is shown that recent measurements of size dependence of the optical properties of particles, actual temperature of the mixture during pyrolysis of initial substances, and the subsequent growth of nanoparticles require a serious revision of current conceptions regarding the temperature dependence of particle yield and growth rate. Based on this analysis, unified regularities in these processes, with various temperatures and types of initial substances, are suggested. The last section of the paper contains a short review of the methods for modeling the processes of carbon nanoparticle formation in shock waves. Emphasis is placed on the necessity for the elaboration of more general models describing the detailed changes in particle properties during the growth process and the unified regularities of particle growth from hydrocarbons and hydrogen-free precursors as determined in experiments. © 2011 Elsevier Ltd. All rights reserved. Source


Naidis G.V.,RAS Joint Institute for High Temperatures
Applied Physics Letters | Year: 2011

Results of modeling of streamer propagation along helium jets for both positive and negative polarities of applied voltage are presented. Obtained patterns of streamer dynamics and structure in these two cases are similar to those observed in experiments with plasma jets. © 2011 American Institute of Physics. Source

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