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Thermal profile of a lanthanum hexaboride heaterless hollow cathode

Thermal profile of a lanthanum hexaboride heaterless hollow cathode
Thermal profile of a lanthanum hexaboride heaterless hollow cathode
Higher power cathodes are increasingly utilizing LaB6 emitters due to their increased emission current density capabilities over barium oxide emitters, however, these emitters require higher operating temperatures which poses a significant challenge to maintain heater reliability. Hence, there is ongoing development of heaterless hollow cathodes that allow for potentially higher reliability through design simplicity of removing the heater component, and in addition, there is potential savings in mass, volume, ignition time and power. In this study a LaB6 heaterless hollow cathode with imbedded high temperature thermocouple instrumentation demonstrated reliably operation in diode mode from 5-8 A at xenon flow rates of 0.2-1.75 sccm. Thet emperature profile of the emitter is characterized through ignition, which lasts up to 50 seconds. In addition, pyrometer measurements in an open keeper configuration have shown the emitter surface temperature to be significantly lower than that predicted by the Richardson equation for LaB6 emitter, perhaps indicating a strong influence of the surface chemistry.
IEPC -2017 -291
Daykin-Iliopoulos, Alexander
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Golosnoy, Igor
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Gabriel, Stephen
ac76976d-74fd-40a0-808d-c9f68a38f259
Daykin-Iliopoulos, Alexander
0caedbac-93a0-45c9-ae31-02f6c70ab8c0
Golosnoy, Igor
40603f91-7488-49ea-830f-24dd930573d1
Gabriel, Stephen
ac76976d-74fd-40a0-808d-c9f68a38f259

Daykin-Iliopoulos, Alexander, Golosnoy, Igor and Gabriel, Stephen (2017) Thermal profile of a lanthanum hexaboride heaterless hollow cathode. 35th International Electric Propulsion Conference, Georgia Institute of Technology, United States. 08 - 11 Oct 2017. IEPC -2017 -291 .

Record type: Conference or Workshop Item (Paper)

Abstract

Higher power cathodes are increasingly utilizing LaB6 emitters due to their increased emission current density capabilities over barium oxide emitters, however, these emitters require higher operating temperatures which poses a significant challenge to maintain heater reliability. Hence, there is ongoing development of heaterless hollow cathodes that allow for potentially higher reliability through design simplicity of removing the heater component, and in addition, there is potential savings in mass, volume, ignition time and power. In this study a LaB6 heaterless hollow cathode with imbedded high temperature thermocouple instrumentation demonstrated reliably operation in diode mode from 5-8 A at xenon flow rates of 0.2-1.75 sccm. Thet emperature profile of the emitter is characterized through ignition, which lasts up to 50 seconds. In addition, pyrometer measurements in an open keeper configuration have shown the emitter surface temperature to be significantly lower than that predicted by the Richardson equation for LaB6 emitter, perhaps indicating a strong influence of the surface chemistry.

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Published date: 8 October 2017
Venue - Dates: 35th International Electric Propulsion Conference, Georgia Institute of Technology, United States, 2017-10-08 - 2017-10-11

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Local EPrints ID: 417900
URI: http://eprints.soton.ac.uk/id/eprint/417900
PURE UUID: 05a3293e-168b-45a3-a138-389b8965aebe

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Date deposited: 16 Feb 2018 17:30
Last modified: 03 Aug 2020 16:31

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Contributors

Author: Alexander Daykin-Iliopoulos
Author: Igor Golosnoy
Author: Stephen Gabriel

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