The distribution of bright and dark areas in glow discharge
Aug 24, 2026| The distribution of bright and dark areas in glow discharge
01
Aston Dark Zone
It is closely attached to the cathode surface. At this point, electrons have just been emitted from the cathode, and the energy is relatively low. They have not been able to fully collide with gas molecules to excite and emit light.
This zone was named after the British physicist Francis W. Aston (1877–1945). In the early research on glow discharge, Aston conducted experimental studies on gas discharge phenomena, especially the research on the initial motion of electrons near the cathode and the structure of the dark zone.
02
Cathode Glow Zone
Electrons gain energy due to the electric field and collide with gas molecules or atoms to emit light.
03
Crookes Dark Zone
The electric field is the strongest here, and electrons are accelerated rapidly. The number of electrons is small and the energy is just starting, so the collision to excite and emit light is not obvious.
This zone was named after the British physicist William Crookes (1832–1919). He made significant contributions to the study of low-pressure discharge tubes, and the most famous one is the "Crookes tube", which is the early cathode ray tube.
04
Negative Glow Zone
This is the cathode light column zone. Electrons gain sufficient kinetic energy and undergo inelastic collisions with gas molecules, exciting and emitting light. This is a clear light-emitting area and also the brightest area.
05
Faraday Dark Zone
The kinetic energy of electrons is partially dissipated, and the excitation collision efficiency decreases, resulting in the formation of a dark zone.
This zone was named after the famous British scientist Michael Faraday (1791–1867), who was one of the founders of electromagnetism and electrochemistry. He conducted experiments and descriptions on gas discharge phenomena.
06
Positive Column Zone
This is the longest light-emitting section. The electron drift and ion drift jointly maintain ionization, and the light emission is relatively uniform.
07
Anode Dark Zone
Close to the anode, some electrons have lost energy, and the light-emitting efficiency decreases again. The electric field is weaker, and there are a few ionizations.
08
Anode Glow Zone
The electric field changes abruptly near the anode surface. Electrons are accelerated, and they collide with residual gas molecules, generating a small amount of stimulated emission of light.
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