Positive pillar

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Luminous zones (cathode light and positive column) and voltage distribution in a low-pressure gas discharge with cold cathodes

The positive column is the self-neutralizing part of a gas discharge ; Ionization through electron impact and particle losses through diffusion are in equilibrium.

In fluorescent tubes and fluorescent lamps, the positive column provides the main part of the light or ultraviolet emission.

Since the glow of the positive column does not fill the entire discharge space with a direct current discharge (especially during longer operation), fluorescent tubes and fluorescent lamps can only be operated with alternating current .

The positive column does not appear in glow lamps - only the cathode is covered by the cathode skin and the negative glow light (see glow discharge ).