APPLIED RESEARCH ON FIELD EMISSION CATHODES.
Quarterly rept. no. 3, 15 Dec 63-15 Mar 64,
FIELD EMISSION CORP MCMINNVILLE OR
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Three large needle-shaped field emission cathodes were tested in diode tubes. Shaping of these cathodes to lessen the effect of the support filaments on the terminal electric fields resulted in an increase in the average beam perveance realized during their operation to a value 47 greater than the average realized during earlier operation of otherwise similar needles. Correction of faults, which became apparent upon testing of edgeshaped single crystal tungsten field emission cathodes, led to the development of an electrochemical means for the shaping of such structures. The main advantage of this technique is to avoid cold working of the material. An emitted beam of 100 amperes at 200 kv, corresponding to a micro-perveance of 1, has thus far been realized from such an edge. A beam tester for the study of electrostatic focusing of the emission from a large, high voltage, field emission needle was evacuated and is ready for testing. The action of a suitable electrostatic field upon a magnetically constrained electron beam to reduce the transverse component of electron velocity was studied by means of the electrolytic tank analogue and Buschs theorem. Author