Review on Impregnated and Reservoir Ba Dispenser Cathodes

Roquais, Jean-Michel; Vancil, Bernard; Green, Michael

doi:10.1007/978-3-030-47291-7_2

Cited by 6 publications

(3 citation statements)

References 61 publications

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“…Scandate cathodes are also "activated" (described in Refs. [104]- [107]) like Band M-cathodes by annealing at high temperature (>1200 • C), for times on the order of hours, sometimes under applied electric fields [10], [106], [108], [109].…”

Section: Emerging Scandate Cathodesmentioning

confidence: 99%

“…4) Sc and cation desorption: While the detailed configuration of adsorbates on W surfaces is widely acknowledged to be critical to determining cathode emission behavior, these configurations are not necessarily invariant over the life of a cathode. In B-type cathodes the depletion of available Ba via evaporation from electron emitting surfaces has been understood to be a lifetime-limiting effect [28], [32], [46], [107], [196]- [199]. It has also been reported that (near) steady-state surface coverages of Ba during operation of Btype and M-type cathodes were both less than optimal to achieve maximum work function reduction [86].…”

Section: Semiconductor Modelmentioning

confidence: 99%

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A Review of Sc-containing "Scandate" Thermionic Cathodes

Seif¹,

Zhou²,

Liu³

et al. 2022

Preprint

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Although thermionic emission has been studied for more than 100 years, recent interest in novel electron devices for military and civilian use has led to a surge in demand for cathodes with enhanced emission properties (e.g. higher current density, more uniform emission, lower operating temperatures, or extended in-service longevity). Sc-containing "scandate" cathodes have been widely reported to exhibit superior emission properties compared to previous-generation thermionic cathodes, including oxide, B-, and M-type cathodes. Despite extensive study spanning several decades, the mechanism by which the addition of Sc enhances cathode emission remains ambiguous, and certain limitations -non-uniform emission, low reproducibility, inconsistent longevity -continue to prevent widespread commercial integration of scandate cathodes into electron devices. This review attempts to survey the literature to-date addressing the fabrication, structure, and properties of scandate cathodes, with particular attention to studies addressing the role of Sc in enhancing emission.

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Section: Emerging Scandate Cathodesmentioning

confidence: 99%

Section: Semiconductor Modelmentioning

confidence: 99%

A Review of Sc-containing "Scandate" Thermionic Cathodes

Seif¹,

Zhou²,

Liu³

et al. 2022

Preprint

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“…Impregnated cathodes are serving as the workhorse electron source of high-power and high-frequency vacuum devices. [1][2][3][4] An impregnated cathode comprises the multiporous tungsten metal and the inorganic non-metal impregnant. Barium calcium aluminates are the most popular compounds as active materials.…”

Section: Introductionmentioning

confidence: 99%

Phase selectivity and environmental stability of 612‐aluminate synthesized by sintering Co‐precipitated precursor

Dong,

Zhou,

Gong

et al. 2023

Int J Applied Ceramic Tech

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The environmental stability of barium calcium aluminate for impregnated cathodes is significant for storing impregnants and fabricating thermionic cathodes. In this work, two types of phase structures are obtained in the 612‐type aluminate. The Ba3CaAl2O7 single‐phase structure is obtained if the crucible is uncovered after sintering for 300 min at 1200°C. In contrast, the Ba3Al2O6 and BaCO3 dual‐phase structure is achieved by suppressing the solid‐state reaction by covering the crucible and reducing the sintering duration to 75 min. The dual‐phase sample exhibits superior environment stability to the single‐phase one when exposed to moist air. The reason could be attributed to the smaller specific surface area and total pore volume of the dual‐phase sample due to the incomplete liberty of gases in sintering. Because of their identical compositions, the cathodes impregnated with different sintered phases possess comparable electron emission capacities. This work provides an effective process to synthesize 612‐aluminate with good environmental stability and emissive capacity.

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$\mathbf{SrVO_{3}}$ electron emission cathodes with stable, >250 mA/cm² current density

Sheikh

Lin

Jacobs

et al. 2023

2023 24th International Vacuum Electronics Conference (IVEC)

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Review on Impregnated and Reservoir Ba Dispenser Cathodes

Cited by 6 publications

References 61 publications

A Review of Sc-containing "Scandate" Thermionic Cathodes

A Review of Sc-containing "Scandate" Thermionic Cathodes

Phase selectivity and environmental stability of 612‐aluminate synthesized by sintering Co‐precipitated precursor

$\mathbf{SrVO_{3}}$ electron emission cathodes with stable, >250 mA/cm² current density

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Review on Impregnated and Reservoir Ba Dispenser Cathodes

Cited by 6 publications

References 61 publications

A Review of Sc-containing "Scandate" Thermionic Cathodes

A Review of Sc-containing "Scandate" Thermionic Cathodes

Phase selectivity and environmental stability of 612‐aluminate synthesized by sintering Co‐precipitated precursor

$\mathbf{SrVO_{3}}$ electron emission cathodes with stable, >250 mA/cm2 current density

Contact Info

Product

Resources

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$\mathbf{SrVO_{3}}$ electron emission cathodes with stable, >250 mA/cm² current density