V.I. Kristya - Dr. Sc. (Phys.-Math.), Professor, Kaluga branch of the Bauman MSTU E-mail: kristya@bmstu-kaluga.ru V.V. Prasitsky - Dr. Sc. (Eng.), Professor, Kaluga branch of the Bauman MSTU E-mail: sintel40@yandex.ru G.V. Prasitsky - Student, Kaluga branch of the Bauman MSTU E-mail: akatosh74@yandex.ru Kyaw Zay - Post-graduate Student, Kaluga branch of the Bauman MSTU E-mail: kyawzay49@gmail.com

Glow discharge in atmospheric pressure gases is of a considerable interest for technological applications. At the discharge current values up to several amperes it contracts on the cathode in the spot of a small radius, i.e. burns in the normal mode. As a result, a substantial heating of the cathode in the spot takes place by the heat flow from the discharge cathode layer. Calculations of the temperature distribution in the cathode volume and at the cathode surface were fulfilled in a number of works for the case of homogeneous cathode structure and constant heat conductivity. The real electrode, however, can have a composite structure, i.e. consist of a thin emission layer and a metal substrate with different heat conductivities. But the influence of this factor on the heat transfer in the cathode volume and its surface temperature has not been studied previously. In this paper, a model of the heat transport in the flat two-layer electrode, performing the cathode function, in the presence the normal glow discharge spot on its surface, is developed. The analytic solution of the heat conduction equation in the discharge volume is found and an analytic expression for its temperature in the spot centre is obtained. The dependence of the cathode surface temperature on the substrate thickness and its heat conductivity is calculated. It is shown that using of the two-layer cathode having the substrate with sufficiently high conductivity can lead to a significant reduction of its emission layer temperature in comparison with the one-layer cathode of the same thickness.

 

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