The hollow cathode effect allows electrical conduction at a lower voltage or with more current in a
cold-cathode gas-discharge lamp
Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma.
Typically, such lamps use a
noble gas (argon, neon, krypton, and xenon) or a mixture of the ...
when the cathode is a conductive tube open at one end than a similar lamp with a flat cathode.
The hollow cathode effect was recognized by
Friedrich Paschen in 1916.
In a hollow cathode, the electron emitting surface is in the inside of the tube. Several processes contribute to enhanced performance of a hollow cathode:
*The
pendulum
A pendulum is a weight suspended from a wikt:pivot, pivot so that it can swing freely. When a pendulum is displaced sideways from its resting, Mechanical equilibrium, equilibrium position, it is subject to a restoring force due to gravity that ...
effect, where an electron oscillates back and forth in the tube, creating secondary electrons along the way
*The
photoionization
Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule.
Cross section
Not every interaction between a photon and an atom, or molecule, will result in photoionization. The prob ...
effect, where photons emitted in the tube cause further ionization
*Stepwise ionization
*
Sputtering
In physics, sputtering is a phenomenon in which microscopic particles of a solid material are ejected from its surface, after the material is itself bombarded by energetic particles of a plasma or gas. It occurs naturally in outer space, and ...
The hollow cathode effect is utilized in the electrodes for
neon sign
In the signage industry, neon signs are electric signs lighted by long luminous gas-discharge tubes that contain rarefied neon or other gases. They are the most common use for neon lighting, which was first demonstrated in a modern form in Dec ...
s, in
hollow-cathode lamps, and more.
References
Atomic physics
Electrodes
Gas discharge lamps
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