Abstract. Electric field enhanced corona plasma discharge in ozone generator diode of axial symmetry has been investigated and characterized in theory. The cathode K of diode is made of a large number of sharpened nozzles arranged on various radial planes on the axial mast and pervaded in oxygen gas inside the anode cup A, produces high fields over MV/m and aids in the formation of a corona plume of dense ozone cloud over the cathode surface. An r-z finite difference scheme has been devised and employed to numerically determine the potential and electric field distributions inside the diode. The analyses of cathode emissions revealed a field emission domain conformed to modified ChildLangmuir diode-current. Passage of higher currents (over µA) in shorter A-K gaps d gave rise to cathode heated plasma extending from the corona to Saha regimes depending on local temperature. Plasma densities of order 10 2 -10 6 m -3 are predicted in these. For larger d however, currents are smaller and heating negligible and a negative corona favoring ozone formation is attained. High ozone yields about 20 per cent of oxygen input is predicted in this domain. The generator so developed will be applied to various important applications such as, purification of ambient air /drinking water, ozone therapy, and so on.
Abstract. Engineering details of a high voltage driven corona-plasma ozone generator are described. The plasma diode of generator has coaxial cylindrical geometry with cathode located inside anode. Cathode is made of a large number of radial gas nozzles arranged on central tubular mast which admits oxygen gas. The sharp endings of the nozzles along with a set of corona rings create the high electric field at the cathode required for formation of dense corona plume responsible for O 3 evolution. A model of coronal plasma generation and ozone production is presented. The plasma formation is strongly dependent on the electric field and temperature in side diode where a high electron density in a low temperature negative corona is suited for high ozone yields. These are established by suitable regulation of A-K gap, voltage, oxygen pressure, and cathodenozzle population.
IntroductionOzone is a powerful disinfectant and oxidant important for purification of drinking water, room air, and environment [1,2]. So also it is used for fumigation and sterilization in operation theatres in hospitals, disinfecting food products to increase shelf life, ozone therapy [3], and many more important applications. Plasma route of ozone generation is highly efficient [1] than other routes such as ultraviolet method. This work discusses the important features of a high-voltage (HV) corona controlled plasma-ozone generator which is under development presently in Pillai's Institute of Information Technology, Engineering, Media Studies and Research (PIIT) New Panvel. Engineering details of this generator are described in present work. A model of corona plasma generation as well as that of ozone production is also described and results presented along with discussions. The generator so developed will be used in many of above various applications.The generator makes use a negative corona discharge formed over the surface of cathode (K) of plasma diode where cathode is raised to a high negative potential (-1 to -60 keV) with respect to anode cup (A). Molecular oxygen O 2 is admitted in the anode-cathode (A-K) gap region and O 2 is split into atomic radicals O -through collisions by electron emissions from cathode. Alongside the radicals combine with free molecules O 2 and form ozone (O 3 ) the allotrope. The process is illustrated below is reversible having half-lives of tens of minutes at the ambient temperature and reduces with increase in temperature.
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