Gas discharge
Encyclopedia : G : GA : GAS : Gas discharge
A gas discharge is an electrical discharge through an ionized gas, i.e. a plasma. The character of the gas discharge critically depends on the frequency or modulation of the current: see the entry on a frequency classification of plasmas.
A glow discharge and arc discharge in low-pressure gas produces visible light with emission spectrum depending on the gas used.
| Gas | Color | Notes |
|---|---|---|
| Helium | Whitish orange; under some conditions may be grayish, bluish, or green-bluish | Used by artists for special purpose lighting. |
| Neon | Red-orange | Intensive light. Used frequently in neon signs and neon bulbs. |
| Argon | Violetish pale lavender blue | Often used together with mercury vapor. |
| Krypton | Grayish dim off-white. May be greenish. At high peak currents bright blue-white. | Used by artists for special purpose lighting. |
| Xenon | Grayish or bluish-gray dim white, at high peak currents very bright green-bluish | Used in xenon flash lamps, xenon HID headlamps, and xenon arc lamps, and by artists for special purpose lighting. |
| Nitrogen | Similar to argon, duller, more pinkish; at high peak currents bright bluish-white, whiter than argon | |
| Oxygen | Violet-lavender, dimmer than argon | |
| Hydrogen | Lavender at low currents, pinkish magenta over 10 mA | |
| Water vapor | Similar to hydrogen, dimmer | |
| Carbon dioxide | Slight bluish-white, in lower currents brighter than xenon | |
| Mercury vapor | Light blue, intense ultraviolet | In combination with phosphors used to generate many colors of light. Widely used in mercury-vapor lamps and Hydrargyrum Medium-Arc Iodide lamps. Often used together with argon. |
| Sodium vapor | Bright yellow | Widely used in sodium vapor lamps. |
See also
External links
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