真しん空くう電でん球きゅう

noun

vacuum bulb

Technical term for a light bulb with a vacuum inside, used in early incandescent lamps or specialized equipment.

• 真しん空くう電でん球きゅうは、フィラメントの酸さん化かを防ふせぐために内ない部ぶを真しん空くうにした電でん球きゅうです。

  A vacuum bulb is a light bulb whose interior is evacuated to prevent oxidation of the filament.