CORONA DISCHARGE

Townsend Avalanche — Ionization Around Sharp Conductors
Voltage (kV) 20.0 kV
Tip Radius (mm) 0.5 mm
Air Pressure (atm) 1.0 atm
—Peak E-field (MV/m)
—Onset Voltage (kV)
—Corona Radius (mm)
OFFDischarge Status
Corona discharge occurs when the electric field around a sharp conductor (tip radius r) exceeds the air breakdown field (~3 MV/m at 1 atm). Electrons are accelerated, ionizing molecules — the Townsend avalanche. Onset: V_onset ≈ E_crit · r · ln(d/r). Basis of ozone generators, electrostatic precipitators, and lightning rods.