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Microwave Discharges for Ozone Hole Study

#0900


Study of Nanosecond Microwave Discharges in Wave Beams and Modeling their Effect on the Atmosphere in the Region of Ozone "Holes"

Tech Area / Field

  • ENV-EHS/Environmental Health and Safety/Environment

Status
3 Approved without Funding

Registration date
19.03.1997

Leading Institute
Russian Academy of Sciences / Institute of Applied Physics, Russia, N. Novgorod reg., N. Novgorod

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Yamanashi University / Dept.of Mechanical System Engineering, Japan, Kofu\nChalmers University of Technology / Institute for Electromagnatic Field Theory and Plasma Physics, Sweden, Gothenburg\nURA 0073/Universite Paris-Sud / Laboratoire de Physique dez Gaz et des Plasmas, France, Orsay\nUniversity of Maryland / Department of Astronomy, USA, MD, College Park

Project summary

The object of the project proposed is investigation of kinetic and plasma chemical processes running is nanosecond microwave discharges produced by wave beams at pressures and air temperatures that correspond to the conditions of upper atmosphere, and a study of prospects of application of such discharges for replenishment of ozone density in the region of local ozone "holes" and for purification of the atmosphere from pollution.

Depletion the atmospheric ozone is one of the very important problems that have arisen recently. Appearance с of ozone "holes" (regions with ozone content 20-50% lower than the usual level) has become & regular event in Antarctic and Arctic regions, and over large industrial centers.

The project deals with the plasma chemical method of artificial replenishment of the ozone layer by means of ionization with powerful microwave radiation. In the ionized region electrons dissociate oxygen molecules, then oxygen atoms are converted into ozone. The most promising way of ozone production in the Earth atmosphere seems to be the way of using an artificial ionized layer (AIL) produced by crossing beams of electromagnetic waves generated by ground-based antenna complexes. Advantages of this scheme of AIL creation are high efficiency of energy transmission, ease of localization of the breakdown region and the possibility to sweep the discharge in the region of the ozone "hole". On the other hand, application of nanosecond pulses makes it possible to make energy cost of ozone molecule formation lower.

The LAP RAS research team has developed an experimental complex for laboratory modeling of plasma chemical processes hi the AIL produced by nanosecond wave beams hi the upper atmosphere- The experiments performed on the complex demonstrated the possibility to efficiently generate ozone in microwave discharges for the first time and revealed optimal regimes of ozone generation in air at low energy cost of molecule formation (20-50 eV per molecule). It was shown that in principle it is possible to replenish ozone in local ozone "holes" by microwave radiation with nanosecond duration in two crossing wave beams.

In order to pass over to field experiments one has to solve a series of principal problems that require preliminary analyses and experimental investigation. The project aims at solving the most important of them, namely:


(1) study of the dynamics of regenerated ozone in an artificial ionized layer taking into account photo-chemical processes (influence of the Sun);
(2) investigation of life time of the regenerated ozone layer with account for real gas composition in the region of the ozone "hole";
(3) determination of the efficiency of destruction of chlorofluorocarbons in a nanosecond microwave discharge;
(4) development of a method for remote diagnostics of minor components of the atmosphere basing on the analysis of emission spectra of the particles excited in the microwave discharge plasma.

It is planned to use in the course of project implementation the experimental set-up available at IAP RAS now having included into the set-up more powerful microwave generators and a distributed source of UV radiation developed at the Russian Scientific-Research Institute of Experimental Physics (RSRIEP). Combination of efforts of the both institutes is absolutely necessary to provide performance of experiments at the conditions most adequate to the conditions of the real atmosphere.

The proposed research series will make it possible to formulate proposals on application of the nanosecond microwave discharge in crossing wave beams in field experiments. The study of photo-chemical and plasma chemical processes will result in construction of a kinetic model describing ozone dynamics in the region of local ozone "holes", and determination of parameters of microwave radiation for generation of ozone at a minimal energy cost and size of ozone "holes", in which regeneration of ozone can be done by means of one microwave set-up. Basing on experimental data, the potential of application of the microwave discharge for remote diagnostics of minor atmospheric components will be determinated for emission spectra of particles excited in plasma. When a nanosecond microwave discharge is used to replenish ozone destruction and to purify the atmosphere from chlorofluorocarbons, this method may be considered as a way to monitor variations of the chemical compositions of the atmosphere produced by the discharge. It is supposed to collaborate with foreign scientists at all stages of carrying out the project.


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