Surface coating influence on scandate cathode performance

Sasaki, Shinji; Yaguchi, Toshie; Nonaka, Yasuhiko; Taguchi, Sadanori; Shibata, M.

doi:10.1016/s0169-4332(02)00557-3

Cited by 13 publications

(6 citation statements)

References 14 publications

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“…The improved electron emission in the Sc-cathodes can be attributed to the decreased work function by two reasons: (1) an adsorbed monolayer of Ba-Sc-O on the tungsten surface; (2) semiconductor model. In 2002, Sasaki [92] found that the electron emission of Sc-cathodes is governed by a certain amount of Sc according to experimental results. Free Sc and free Ba [93] could migrate to the surface of cathode, and the Ba-Sc-O monolayer was formed on the W grains and effectively reduced the work function during activation.…”

Section: Scandia-doped Dispenser (Sdd) Cathodementioning

confidence: 99%

A review on recent progress of thermionic cathode

et al. 2020

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As the performance of vacuum electron devices is essentially governed by the properties of their cathodes, developing efficient and durable thermionic cathode is necessary and highly desired to meet the boosting requirements of vacuum electron devices. This review summarized the progress made in the past decades with a detailed discussion on the occurred various thermionic cathodes and their features, and the understandings of the correlation between the emission properties and the composition, where structure and synthesis method are well illustrated. Furthermore, dispenser cathodes with novel structures and emission mechanism are highlighted to indicate the recent achievement in this area of research, and Sc-cathode is considered as a promising candidate for the next-generation vacuum electron devices due to the greatly improved efficiency. However, challenges still exist to meet the ever-growing demands of thermionic cathode with collaborative requirement of high performance, easy fabrication and inadequate reproducibility.

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Section: Scandia-doped Dispenser (Sdd) Cathodementioning

confidence: 99%

A review on recent progress of thermionic cathode

et al. 2020

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“…A large number of studies showed that based on the current widely used Ba-W cathode, the addition of a certain amount of scandia can significantly improve the emission performance. Therefore, the scandate cathode is considered as one of the main candidates for the next generation high current density cathodes [4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

A review on scandia doped tungsten matrix scandate cathode

et al. 2019

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As the cathode with the highest electron emission capability in the thermionic cathode, the scandate cathode has attracted more and more attention in recent years, especially the scandia doped tungsten matrix scandate cathode. Experimental studies show that scandia doped tungsten matrix scandate cathodes with submicron microstructures exhibit excellent emission capacity, and the pulse emission current density in the space-charge region can be over 35 A cm −2 at 850 °C b. In the direct current (DC) condition with temperature compensation, the emission current density could reach 25 A cm −2 at 850 °C b. The device lifetime is over 3700 h after operating at 950 °C b with the DC loading of 40 A cm −2. The emission mechanism of the scandate cathode including the effect of the surface structure and composition on the work function of the cathode are systematically reviewed.

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“…The addition of scandium oxide to Ba-W dispenser thermionic cathodes can improve the emission by a factor of tens to hundreds at the same operating temperature. Therefore, scandate cathode, the only thermionic cathode candidate for the continuously improved vacuum devices in high emission current, is considered as the next generation high emission cathodes and has attracted great interest (Gaertner et al, 2002;Gison et al, 1989;Hasker et al, 1986;Oostrom & Augustus, 1979;Sasaki et al, 2002;Vancil et al, 2014;Wan & Kordesch, 2013;Yamamoto et al, 1984aYamamoto et al, , 1984b. From 1970s, the study of scandate cathode has been continuing.…”

Section: Introductionmentioning

confidence: 99%

Advances in High Emission Sc₂O₃-W Matrix Cathode Materials

et al. 2016

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Our work on Sc 2 O 3 -W matrix dispenser cathodes had been reviewed in this paper. The cathode with uniform distribution of Sc 2 O 3 had been obtained using liquid-liquid doping method. The cathode had excellent emission property, i.e., the emission current density in pulse condition could reach over 35 A/cm 2 . It was found that the cathode surface was covered by a Ba-Sc-O active substance multilayer with a thickness of about 100 nm, which was different from the monolayer and semiconducting layer in thickness. Furthermore, the observation results displayed that nanoparticles appeared at the growth steps and the surface of tungsten grains of the fully activated cathode. The calculation result indicated that the nanoparticles could cause the increase of local electric fi eld strengths. We proposed the emission model that both the Ba-Sc-O multilayer and the nanoparticles distributing mainly on the growth steps of the W grains contributed to the emission. The future work on this cathode has been discussed.

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Surface coating influence on scandate cathode performance

Cited by 13 publications

References 14 publications

A review on recent progress of thermionic cathode

A review on recent progress of thermionic cathode

A review on scandia doped tungsten matrix scandate cathode

Advances in High Emission Sc₂O₃-W Matrix Cathode Materials

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Surface coating influence on scandate cathode performance

Cited by 13 publications

References 14 publications

A review on recent progress of thermionic cathode

A review on recent progress of thermionic cathode

A review on scandia doped tungsten matrix scandate cathode

Advances in High Emission Sc2O3-W Matrix Cathode Materials

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Advances in High Emission Sc₂O₃-W Matrix Cathode Materials