kaasukehä

Kaasukehä (literally “gas ring”) is a Finnish term used to describe a ring‑shaped region or envelope of gas surrounding an object or inside a system. It is a descriptive concept rather than a single standardized definition, and its exact meaning depends on the disciplinary context.

In astronomy, kaasukehä commonly refers to diffuse gas that surrounds a celestial object, such as the circumgalactic medium around galaxies or circumstellar envelopes around stars. This gas can influence the evolution of the system by participating in processes like gas accretion, star formation, and feedback from energetic events. The term emphasizes the ring- or halo‑like geometry of the gas distribution.

In engineering and industry, kaasukehä may denote an annular layer of shielding or inert gas that protects a process zone from oxidation or contamination. For example, a gas ring can surround a welding arc or a reaction chamber to maintain a controlled atmosphere, or appear as part of the gas distribution in a plasma processing setup.

The term is less common in everyday language and can be replaced with more specific terms in English, such as shielding gas, gas envelope, or gaseous halo, depending on the context. In scientific writing, however, kaasukehä serves as a concise, intuitive label for any ring-shaped gas region involved in the phenomenon being described.

See also: circumgalactic medium, circumstellar envelope, shielding gas, gas blanket.

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