Valentina Khomich | Friedrich-Schiller-Universität Jena (original) (raw)

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Papers by Valentina Khomich

Research paper thumbnail of Utilization of Ultraviolet Radiation of Cold Hollow Cathode Glow Discharge Plasma for Water Disinfection

In this proceeding the results of experimental studies of peculiarities of Escherichia coli water... more In this proceeding the results of experimental studies of peculiarities of Escherichia coli water suspension inactivation by ultraviolet radiation of hollow cathode discharge plasma in different gaseous media are presented. It is shown that efficiency of the inactivation by the discharges on oxygen, mixtures of oxygen with deuterium, and water vapor is essentially higher than that by the discharge on air, as well as the discharges of low and medium pressure mercury lamps.

Research paper thumbnail of Features of sterilization using low-pressure DC-discharge hydrogen-peroxide plasma

IEEE Transactions on Plasma Science, 2002

This investigation studies the theoretical and practical features of sterilization using glow dis... more This investigation studies the theoretical and practical features of sterilization using glow discharge plasma in hydrogen peroxide vapor. It is determined that, in such a system, most sterilization is performed by active particles formed in the plasma, rather than by ultraviolet (UV) radiation (as is the case in gas discharges like air and oxygen). This study shows that sterilization by discharge plasma in hydrogen peroxide vapor is more efficient than sterilization by plasma of the discharge in gases: sterilization time is 2-3 times shorter in open surfaces and 10 times shorter in packed articles. This study's calculations indicate that this enhanced efficiency might be due to fact that concentrations of the main biologically active particles, such as atomic oxygen and oxygen molecules excited to lower metastable states, reach values of ~10 14 -10 15 cm -3 , which is 2-3 order of magnitude higher than that in oxygen plasma at the same parameters of the discharge.

Research paper thumbnail of XV International School on Spectroscopy of Molecules and Crystals

This report presents both the results of experimental investigation of the features of sterilizat... more This report presents both the results of experimental investigation of the features of sterilization by plasma DC glow discharge: a) dependencies of the efficiency of plasma sterilization on discharge parameters; b) ratio between main sterilization factors, and the results of numerical simulation of component composition.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Research paper thumbnail of Peculiarities of Uv Radiation From Hollow Cathode Discharge Plasma Used for Sterilization of Medical Articles

Research paper thumbnail of Apparatus and process for dry sterilization of medical and dental devices and materials

Research paper thumbnail of Sterilization of medical productsin low-pressure glow discharges

Plasma Physics Reports, 2000

Results are presented from experimental and theoretical studies of the sterilization of medical p... more Results are presented from experimental and theoretical studies of the sterilization of medical products by the plasmas of dc glow discharges in different gas media. The sterilization efficiency is obtained as a function of discharge parameters. The plasma composition in discharges in N 2 and O 2 is investigated under the operating conditions of a plasma sterilizer. It is shown that free surfaces of medical products are sterilized primarily by UV radiation from the discharge plasma, while an important role in sterilization of products with complicated shapes is played by such chemically active particles as oxygen atoms and electronically excited O 2 molecules. © 2000 MAIK "Nauka/Interperiodica".

Research paper thumbnail of Comparative Research of Efficiency of Water Decontamination by UV Radiation of Cold Hollow Cathode Discharge Plasma Versus That of Low- and Medium-Pressure Mercury Lamps

IEEE Transactions on Plasma Science, 2000

In this paper, the results of experimental studies of peculiarities of Escherichia coli water sus... more In this paper, the results of experimental studies of peculiarities of Escherichia coli water suspension inactivation by ultraviolet radiation of hollow cathode discharge plasma in different gaseous media are presented. It is shown that efficiency of the inactivation by the discharges on oxygen, mixtures of oxygen with deuterium, and water vapor is essentially higher than that by the discharge on air, as well as the discharges of low-and medium-pressure mercury lamps.

Research paper thumbnail of Investigation of the electron energy distribution function in hollow-cathode glow discharges in nitrogen and oxygen

Plasma Physics Reports, 2001

The mechanism for the formation of the inverse electron distribution function is proposed and rea... more The mechanism for the formation of the inverse electron distribution function is proposed and realized experimentally in a nitrogen plasma of a hollow-cathode glow discharge. It is shown theoretically and experimentally that, for a broad range of the parameters of an N 2 discharge, it is possible to form a significant dip in the profile of the electron distribution function in the energy range ε = 2-4 eV and, accordingly, to produce the inverse distribution with df ( ε )/ d ε > 0. The formation of a dip is associated with both the vibrational excitation of N 2 molecules and the characteristic features of a hollow-cathode glow discharge. In such a discharge, the applied voltage drops preferentially across a narrow cathode sheath. In the main discharge region, the electric field E is weak ( E < 0.1 V/cm at a pressure of about p ~ 0.1 torr) and does not heat the discharge plasma. The gas is ionized and the ionization-produced electrons are heated by a beam of fast electrons (with an energy of about 400 eV) emitted from the cathode. A high-energy electron beam plays an important role in the formation of a dip in the profile of the electron distribution function in the energy range in which the cross section for the vibrational excitation of nitrogen molecules is maximum. A plasma with an inverted electron distribution function can be used to create a population inversion in which more impurity molecules and atoms will exist in electronically excited states. © 2001 MAIK "Nauka/Interperiodica".

Research paper thumbnail of Utilization of Ultraviolet Radiation of Cold Hollow Cathode Glow Discharge Plasma for Water Disinfection

In this proceeding the results of experimental studies of peculiarities of Escherichia coli water... more In this proceeding the results of experimental studies of peculiarities of Escherichia coli water suspension inactivation by ultraviolet radiation of hollow cathode discharge plasma in different gaseous media are presented. It is shown that efficiency of the inactivation by the discharges on oxygen, mixtures of oxygen with deuterium, and water vapor is essentially higher than that by the discharge on air, as well as the discharges of low and medium pressure mercury lamps.

Research paper thumbnail of Features of sterilization using low-pressure DC-discharge hydrogen-peroxide plasma

IEEE Transactions on Plasma Science, 2002

This investigation studies the theoretical and practical features of sterilization using glow dis... more This investigation studies the theoretical and practical features of sterilization using glow discharge plasma in hydrogen peroxide vapor. It is determined that, in such a system, most sterilization is performed by active particles formed in the plasma, rather than by ultraviolet (UV) radiation (as is the case in gas discharges like air and oxygen). This study shows that sterilization by discharge plasma in hydrogen peroxide vapor is more efficient than sterilization by plasma of the discharge in gases: sterilization time is 2-3 times shorter in open surfaces and 10 times shorter in packed articles. This study's calculations indicate that this enhanced efficiency might be due to fact that concentrations of the main biologically active particles, such as atomic oxygen and oxygen molecules excited to lower metastable states, reach values of ~10 14 -10 15 cm -3 , which is 2-3 order of magnitude higher than that in oxygen plasma at the same parameters of the discharge.

Research paper thumbnail of XV International School on Spectroscopy of Molecules and Crystals

This report presents both the results of experimental investigation of the features of sterilizat... more This report presents both the results of experimental investigation of the features of sterilization by plasma DC glow discharge: a) dependencies of the efficiency of plasma sterilization on discharge parameters; b) ratio between main sterilization factors, and the results of numerical simulation of component composition.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Research paper thumbnail of Peculiarities of Uv Radiation From Hollow Cathode Discharge Plasma Used for Sterilization of Medical Articles

Research paper thumbnail of Apparatus and process for dry sterilization of medical and dental devices and materials

Research paper thumbnail of Sterilization of medical productsin low-pressure glow discharges

Plasma Physics Reports, 2000

Results are presented from experimental and theoretical studies of the sterilization of medical p... more Results are presented from experimental and theoretical studies of the sterilization of medical products by the plasmas of dc glow discharges in different gas media. The sterilization efficiency is obtained as a function of discharge parameters. The plasma composition in discharges in N 2 and O 2 is investigated under the operating conditions of a plasma sterilizer. It is shown that free surfaces of medical products are sterilized primarily by UV radiation from the discharge plasma, while an important role in sterilization of products with complicated shapes is played by such chemically active particles as oxygen atoms and electronically excited O 2 molecules. © 2000 MAIK "Nauka/Interperiodica".

Research paper thumbnail of Comparative Research of Efficiency of Water Decontamination by UV Radiation of Cold Hollow Cathode Discharge Plasma Versus That of Low- and Medium-Pressure Mercury Lamps

IEEE Transactions on Plasma Science, 2000

In this paper, the results of experimental studies of peculiarities of Escherichia coli water sus... more In this paper, the results of experimental studies of peculiarities of Escherichia coli water suspension inactivation by ultraviolet radiation of hollow cathode discharge plasma in different gaseous media are presented. It is shown that efficiency of the inactivation by the discharges on oxygen, mixtures of oxygen with deuterium, and water vapor is essentially higher than that by the discharge on air, as well as the discharges of low-and medium-pressure mercury lamps.

Research paper thumbnail of Investigation of the electron energy distribution function in hollow-cathode glow discharges in nitrogen and oxygen

Plasma Physics Reports, 2001

The mechanism for the formation of the inverse electron distribution function is proposed and rea... more The mechanism for the formation of the inverse electron distribution function is proposed and realized experimentally in a nitrogen plasma of a hollow-cathode glow discharge. It is shown theoretically and experimentally that, for a broad range of the parameters of an N 2 discharge, it is possible to form a significant dip in the profile of the electron distribution function in the energy range ε = 2-4 eV and, accordingly, to produce the inverse distribution with df ( ε )/ d ε > 0. The formation of a dip is associated with both the vibrational excitation of N 2 molecules and the characteristic features of a hollow-cathode glow discharge. In such a discharge, the applied voltage drops preferentially across a narrow cathode sheath. In the main discharge region, the electric field E is weak ( E < 0.1 V/cm at a pressure of about p ~ 0.1 torr) and does not heat the discharge plasma. The gas is ionized and the ionization-produced electrons are heated by a beam of fast electrons (with an energy of about 400 eV) emitted from the cathode. A high-energy electron beam plays an important role in the formation of a dip in the profile of the electron distribution function in the energy range in which the cross section for the vibrational excitation of nitrogen molecules is maximum. A plasma with an inverted electron distribution function can be used to create a population inversion in which more impurity molecules and atoms will exist in electronically excited states. © 2001 MAIK "Nauka/Interperiodica".