Construction and performance of practical field emitters from lanthanum hexaboride

The use of field emitters in conventional vacuum devices has been retarded by the technological difficulties associated with the manufacture of reproducible points having a long life. In this paper the construction and performance of emitters from single crystals of lanthanum hexaboride are described and discussed. The results indicate that these emitters are capable of a significantly better performance than other known emitters, and can operate at current densities exceeding 105 A/cm2 for many hundred hours at residual-gas pressures of 10¿9 torr.