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Data comparisons were made between scandate cathodes from several groups world-wide. Processing and test parameters were identical between cathodes. Cathode emission performance was measured in close-spaced diodes. This data will be presented. In addition, surface and cross-sectional morphology via SEM after sintering, impregnation, and activation are shown. Furthermore, the cathodes were installed...
A hollow cathode was fabricated from scandium oxide-doped one-micron tungsten powder. The prepared powder was pressed into a solid billet and sintered in hydrogen. The sintered billet was electron discharge machined to create the hollow emitter. A unique test vehicle was developed consisting of a central wire as anode, a glass-rodded support structure, and a glass envelope, pumped and baked at 400º...
We report on a new cathode which is based on die-pressed matrices made from scandia-doped tungsten powder using the liquid–solid doping technique. Transition temperatures from space charge to temperature limited emission are as low as 840 $^{\circ}{\rm C}_{b}({\rm W})$ for emission of 5 ${\rm A}/{\rm cm}^{2}$ . Transitions are sharper than previously published scandate cathodes and compare favorably...
We report on a new cathode which is based on die-pressed matrices made from scandia-doped tungsten powder. Transition temperatures from space charge to temperature limited emission are as low as 840° Cb(W) for emission of 5 Amps/cm2. Transitions are sharper than previously published scandate cathodes and compare favorably with M and ternary alloy cathodes. We present emission curves on several cathodes,...
We surveyed and studied several field emitters for use in lighting. They were tested in miniature flood lamps with cathodo-luminescent phosphor screens. The test formats were 1) lamps pumped, baked, side-gettered and sealed off; 2) lamps pumped, baked, forward-gettered and sealed off; 3) lamps left open and tested in an ultra-high vacuum system (10−10 torr); 4) lamps tested in pulsed mode, 10% duty...
This paper reports on design and process improvements for wire-suspended cathodes, which were first presented one year ago. These improvements provide lower power, further reduction in size, better stability and accuracy, and higher loading. Current assemblies dissipate less than 150 milliwatts at cathode diameter of .33 mm. The cathodes are too small for use with conventional heaters and so are heated...
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