Regime Controlled by Electron Attachment

This regime takes place if the balance of charged particles is due to the volume processes (4-15) and the discharge parameters correspond to the inequality opposite that of (4-19). Negative ions produced by electron attachment go almost instantaneously into ion-ion recombination, and electron losses are mostly due to the attachment process. The steady-state (4-16) solution for the attachment-controlled regime is 

In the attachment-controlled regime the electron attachment is usually fasterthan recombination, and relation (4-13) actually requires h T ) K T ). Typical functions of h T ) and a(Te) are shown in Fig. 4-15 and have a single crossing point T, which determines the steady-state electron temperature for a non-thermal discharge that is self-sustained in the attachment-controlled regime. 

Non-Thermal Discharge Regime Controlled by Charged-Particle Diffusion to the Walls The Engel-Steenbeck Relation 

When pressure is relatively low and the inequality opposite that of (4-15) is valid, the balance of charged particles is provided by competition of ionization in volmne and diffusion of 

This is the Engel-Steenbeck relation for the diffusion-controlled regime of nonequilibrium discharges. Here I is the ionization potential, /r, is the ion mobility, to is the electron-neutral gas-kinetic cross section, and m is the electron mass. If gas temperature is fixed (for example, at room temperature), the parameters p,ip and n /p are constant and the Engel-Steenbeck relation can be presented as 

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