Preparation and characterization of scandia and Re doped tungsten matrix impregnated cathode

Wang, Jinshu; Li, Lili; Liu, Wei; Wang, Yanchun; Zhao, Lei; Wang, Yiman

doi:10.1016/j.jpcs.2007.05.014

Cited by 13 publications

(2 citation statements)

References 15 publications

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“…Scandia-doped tungsten thermionic cathodes (referred to as scandate cathodes) are promising candidates for application in microwave tubes [ 1 , 2 ], traveling wave tubes (TWTs) [ 3 , 4 ], satellite communication [ 5 ] and vacuum electron devices (VEDs) [ 6 , 7 , 8 , 9 , 10 ] owing to their reported enhancement of electron emission, delivering higher current densities at lower temperatures [ 1 , 3 , 5 , 6 , 8 , 11 , 12 ] than conventional dispenser cathodes, i.e., oxide cathodes [ 13 , 14 , 15 , 16 ], B-type cathodes [ 17 , 18 , 19 , 20 ], and M-type cathodes [ 21 , 22 , 23 ]. Consequently, scandate cathode technology has received significant attention over recent decades.…”

Section: Introductionmentioning

confidence: 99%

Near-Surface Material Phases and Microstructure of Scandate Cathodes

et al. 2019

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Scandate cathodes that were fabricated using the liquid-solid process and that exhibited excellent emission performance were characterized using complementary state-of-the-art electron microscopy techniques. Sub-micron BaAl2O4 particles were observed on the surfaces and edges of tungsten particles, as seen in cross-section samples extracted from the scandate cathode surface regions. Although several BaAl2O4 particles were observed to surround smaller Sc2O3 nanoparticles, no chemical mixing of the two oxides was detected, and in fact the distinct oxide phases were separately verified by chemical analysis and also by 3D elemental tomography. Nanobeam electron diffraction confirmed that the crystal structure throughout W grains is body-centered cubic, indicating that they are metallic W and did not experience noticeable changes, even near the grain surfaces, as a result of the numerous complex chemical reactions that occur during cathode impregnation and activation. 3D reconstruction further revealed that internal Sc/Sc2O3 particles tend to exhibit a degree of correlated arrangement within a given W particle, rather than being distributed uniformly throughout. Moreover, the formation of Sc/Sc2O3 particles within W grains may arise from W surface roughening that occurs during the liquid-solid synthesis process.

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Section: Introductionmentioning

confidence: 99%

Near-Surface Material Phases and Microstructure of Scandate Cathodes

et al. 2019

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“…It has been proved to be able to provide about 50A/cm 2 knee point emission current density at 850 b [1] [2] . But the coarsen granules and fragile matrix after sintering generally lead to emission capability decreasing and surface roughing while adopting surface lathe machining.…”

Section: Introductionmentioning

confidence: 99%

A novel nanocomposite scandia-tungsten coated dispenser cathode

Wang

2009

2009 IEEE International Vacuum Electronics Conference

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This paper will present a novel nanocomposite scandia-tungsten coated dispenser cathode, which has the capability to provide more than 150A/cm 2 knee point current density at 1000 ℃ b . The authors pointed out that the generation and maintenance of emissive islets on the cathode surface is the main factor to decide the Sc-type cathodes emission mechanism is incline to dominating thermionic emission or field enhancement thermionic emission.

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