Main discharge initiation and maintenance mechanisms

Cold discharge plasmas - Electrical properties

Figure 1 - Drift speeds measured in different gases and associated collision frequencies

Figure 2 - Radial profile of charged particle density ( ne &#61; ni ) in a tube of radius R as a function of parameter  &#61; ν I / (νI &#43; νiN) (from [7]).

Figure 3 - Effect on charged particle density of a body of radius RS immersed in a plasma

Figure 4 - Potential profile between a plasma (0 potential) and a negatively polarized substrate (or wall) (potential VS): ion sheath and transition region

Figure 5 - Variations in charged particle density and reduced potential calculated for an ion sheath in planar geometry within the framework of Bohm&#039;s theory

Figure 6 -  Self-polarization of a floating surface polarized by a voltage VS

Figure 7 - Electron density and temperature of usual and straight discharges corresponding to a constant value of the Debye length

Figure 8 - Temperature evolution of electrons ( Te) and neutrals (TN) in an arc discharge at variable pressure and current (from [8] and [9])

Figure 9 - Plasma classification in terms of electron density and degree of ionization for different types of discharge (from [10])

Figure 12 - Current growth in a Townsend discharge for two different values of the reduced field such that ( E/p)2 &gt; (E/p)1

Figure 13 - Townsend coefficients

Figure 14 -  Law of similitude: characteristic I (V) of two discharges of different dimensions at a fixed value of the product pd

Figure 15 - Paschen&#039;s law for different gases: variation of the disruptive potential VD as a function of the product of pressure and interelectrode distance (after [13])

Figure 16 - Architecture of a normal low-pressure glow discharge

Figure 17 - Spatial variations in electric field and charged particle densities in a helium glow discharge: results of a numerical model (from [15])

Figure 18 - Theoretical values for the ratio of electronic temperature to ionization potential as a function of the product of pressure and tube radius, in a positive column

Figure 19 - Energy gain mechanisms for electrons in an RF discharge due to movement of the electrode sheaths, materialized by the electric field profile E, at speed vg

Figure 20 - Microwave breakdown field as a function of pressure in helium containing traces of mercury (from [16])

Figure 21 - RMS field values for breakdown and maintenance of a diffusion-controlled HF discharge (diffusion length Λ) in hydrogen (from [17])

Figure 22 - Validity limits of diffusion-controlled HF discharge theory (according to [18])

Figure 23 - Microwave cavity discharge

Figure 24 - Axial profile of electron density in an argon discharge, for different pressures (from [19])

Figure 25 - Variation of parameter θ in argon (from [19])