公开(公告)号：US10083812B1

公开(公告)日：2018-09-25

申请号：US15359436

申请日：2016-11-22

Applicant: Applied Physics Technologies, Inc.

Inventor： William A. Mackie ,  Gerald G. Magera ,  Joshua M. Lovell

IPC: H01J1/304 ,  H01J9/02

CPC classification number: H01J1/3044 ,  H01J9/025 ,  H01J2201/30407 ,  H01J2201/30484 ,  H01J2209/0223

Abstract: An electron source emitter is made from transition metal carbide materials, including hafnium carbide (HfC), zirconium carbide (ZrC), titanium carbide (TiC), vanadium carbide (VC), niobium carbide (NbC), and tantalum carbide (TaC), which are of high refractory nature. Preferential evaporating and subsequent development of different crystallographic planes of the transition metal carbide emitter having initially at its apex a small radius (50 nm-300 nm) develop over time an on-axis, sharp end-form or tip that is uniformly accentuated circumferentially to an extreme angular form and persists over time. An emitter manufactured to the (110) crystallographic plane and operating at high electron beam current and high temperature for about 20 hours to 40 hours results in the (110) plane, while initially not a high emission crystallographic orientation, developing into a very high field emission orientation because of the geometrical change. This geometrical change allows for a very high electric field and hence high on-axis electron emission.