Electron source and electron beam apparatus

摘要

Provided is an electron source which outputs a stable electron beam even when vibration is applied from the external to an apparatus which uses the electron source. The electron source is provided with an insulator (5); two conductive terminals (4) arranged at an interval on the insulator (5); a long filament (3) stretched between the conductive terminals (4); and a needle-like cathode (1) having an electron emitting section attached to the filament (3). The vertical cross-section shape of the filament (3) in the axis direction has a long direction and a short direction, and the maximum length in the long direction is 1.5 times or more but not more than 5 times the maximum length in the short direction.