Stable, High Density Field Emission Cold Cathode

The practical application of the field emission electron source has heretofore been impeded by insufficient reliability. Instability (i.e., changes in emitted current at a fixed applied voltage) results from changes in the cold cathode surface associated with contamination and sputtering. The cold clean cathode is shown to be electrically stable at dc emission densities up to 107 amp/cm2. Techniques are discussed which permitted stable operation of a single needle tungsten cathode during 1000 hr at an average beam power of 35 w (corresponding to a beam power density of 35 billion w per unit cathode area). A simple method is described which permits reconditioning of the cathode surface when required, and apparently extends life indefinitely; operating periods in excess of 12 000 hr are reported. An explanation is suggested for the small, gradual residual changes observed in the emitted current.

[1]  D. Alpert,et al.  Extension of the low pressure range of the ionization gauge. , 1950, The Review of scientific instruments.

[2]  L. Nordheim.  The Effect of the Image Force on the Emission and Reflexion of Electrons by Metals , 1928 .

[3]  D. Alpert,et al.  Ultra‐High Vacuum. II. Limiting Factors on the Attainment of Very Low Pressures , 1954 .

[4]  W. P. Dyke.  Field Emission, A Newly Practical Electron Source , 1960, IRE Transactions on Military Electronics.

[5]  Erwin W. Müller,et al.  Elektronenmikroskopische Beobachtungen von Feldkathoden , 1937 .

[6]  F. J. Norton.  Permeation of Gases through Solids , 1957 .

[7]  R A Millikan,et al.  Relations of Field-Currents to Thermionic-Currents. , 1928, Proceedings of the National Academy of Sciences of the United States of America.

[8]  W. P. Dyke,et al.  Field Emission: Large Current Densities, Space Charge, and the Vacuum Arc , 1953 .

[9]  W. P. Dyke,et al.  THE FIELD EMISSION INITIATED VACUUM ARC. I. EXPERIMENTS ON ARC INITIATION , 1953 .

[10]  M. De.  Handbuch der Physik , 1957 .

[11]  W. W. Dolan.  Current Density Tables for Field Emission Theory , 1953 .

[12]  W. P. Dyke,et al.  THE FIELD EMISSION INITIATED VACUUM ARC. II. THE RESISTIVELY HEATED EMITTER , 1953 .

[13]  R. Haefer.  Experimentelle Untersuchungen zur Prüfung der wellenmechanischen Theorie der Feldelektronenemission , 1940 .

[14]  Robert A. Millikan,et al.  Fields currents from points , 1928 .

[15]  J. L. Boling,et al.  Blunting of Tungsten Needles by Surface Diffusion , 1958 .

[16]  W. P. Dyke,et al.  Determination of the Surface Tension and Surface Migration Constants for Tungsten , 1960 .

[17]  R. Fowler,et al.  Electron Emission in Intense Electric Fields , 1928 .