a X-ray tube in which electrons are ejected from the cathode by a sufficiently strong electric field
An X-ray tube that uses a cold cathode, relying on the tube voltage to pull electrons from it to the anode. ... (05 Mar 2000) ... 
Type: Term Definitions: 1. an x-ray tube that uses a cold cathode, relying on the tube voltage to pull electrons from it to the anode.