Plasma Engineering

Chapter 3

Electrical Discharges

3.1 Electrical breakdown and Paschen law

Electrical breakdown in low-pressure gases is characterized by the short transition time from an insulating interelectrode gap to a relatively high electrical conductivity gap. The transition time varies from ns to µs scale depending on gap size, electrode surface state, etc. (Figure 3.1).

Figure 3.1 Schematics of the electron avalanche and gas breakdown.

Let us consider phenomena of the electrical breakdown in a low-pressure gas. When a high voltage is applied to the gap, the primary electrons flow in direction from cathode to the anode, multiplying new electrons in an avalanche ...