Crookes dark space

noun Physics.
  1. the dark space between the cathode glow and the negative glow in a vacuum tube, occurring when the pressure is low.

Origin of Crookes dark space

First recorded in 1890–95; after Sir W. Crookes
Also called Crookes space.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018