Theory of the negative anode drop in low-pressure discharges

A study of anode area physical parameters of asymmetric combined gas discharge

“…This is true only if the electron flux entering the anode makes up an insignificant part of the electron flux entering the layer. To eliminate these restrictions, in [ 32 ], an implicit, relative to equation was obtained: Here erf ( x ) is probability integral and the parameter …”

“…Electron generation and acceleration to high energies of up to hundreds eV under the action of a microwave electric field occurs in an intense lilac glow zone – 3 separated from the product – 1 by a thin surface layer – 2. Inside surface layer-2, a negative potential drop between the product and the plasma occurs [ 32 , 33 ]. On the outside, the electron acceleration zone – 3 borders on the deceleration zone – 4 which, in turn, consists of thinner layers of yellow, orange and red colors, inside which energetic electrons lose their energy as a result of elastic and inelastic collisions with argon atoms [ 28 ].…”

“…A negative potential drop between the product and the plasma occurs in a narrow near-surface layer between them and is determined by the formula where Boltzmann constant, electron temperature, electron current strength, electron saturation current, absolute value of the electron charge. In this case, the potential profile is nonmonotonic, and a potential well for slow electrons is formed near the workpiece surface where a significant part of them is trapped [ 32 ]. Only electrons with a sufficiently high energy enter the surface of the product.…”

“…Further, in Section 3.1 , the values of the main plasma parameters of the anode region were obtained from the analysis of the family of current-voltage characteristics of the gas discharge ( Figure 3 ) based on the Langmuir theory, as well as the modern theoretical research results presented in [ 32 , 33 ]: electron temperature, ion concentration, average electron energy in the acceleration zone, floating potential and others at different levels of microwave power.

Figure 3 Dependences i (ϕ 0 ) of the constant component of the current flowing through the unit on the constant bias potential supplied to the product, recorded on a copper 8 mm diameter cooper ball at different microwave power levels.

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