Effect of the gas dynamic structure of a flow on the parameters of a self-sustained discharge. II

Calculation of time dependence of the electrode surface temperature in the cathode spot of atmospheric pressure normal glow discharge

“…Therefore, the cathode temperature in the spot and in the discharge cathode sheath can be con sidered as constant and equal to T sc . Because the length d c of the discharge cathode sheath is much less than r s , nearly all heat power gen erated in the sheath is absorbed by the cathode through the spot [6,9,12], and the heat flow density in it equals to (17) with the spot radius defined by expression (18) where j and U c are the normal discharge current den sity and cathode voltage drop, I is the discharge cur rent.…”

“…Suppose that at the cathode surface cir cular section of the radius r s (the cathode spot) a heat flow is falling, which density q s is uniform over the spot [5,6,9], but can be varied with time, as well as the spot radius r s . Then the temperature distribution in the cathode volume T(r, z, t) is described by the non sta tionary heat conduction equation (1) with boundary condition at the surface…”

“…whereas gas density reduction due to its heating can be taken into account by introducing the effective gas pressure p [6,11]: Equations (13) and (17)- (22) form a closed non linear system describing variation of the cathode sur face temperature in the spot and the discharge cathode sheath parameters after discharge ignition. Its solution can be obtained numerically in successive time moments with the iteration method.…”

“…After the discharge igni tion, the cathode surface in the spot and the gas near the spot are heated by the flow of heat released under charged particle motion in the discharge cathode sheath, which results in a local reduction of the gas density, a decrease of the discharge normal current density, and an increase of the spot radius with time. Experimental and theoretical investigations of the atmospheric pressure glow discharge parameters, as well as the temperature of the gas in the discharge cathode sheath and at the cathode surface, were carried out in a number of works [6][7][8][9][10][11][12][13][14][15][16] for the sta tionary discharge mode. But the dynamics of the indi cated values at the stage of their transition to the steady state was studied only experimentally in [12].…”

Influence of cathode temperature on the parameters of an atmospheric pressure dc glow discharge

“…As noted in the introduction, there are no full-scale calculations of the APGD taking into account the heat generation in the cathode fall region. Therefore, let us use the onedimensional model [20] for an analysis of the influence of the cathode temperature on the APGD parameters. This model is essentially a generalization of scaling laws [21] to include inhomogeneous neutral density.…”