SPIDER is the negative ion source testbed for ITER neutral beam injector. It is currently the largest negative ion source ever built, equipped with a 100 keV accelerator, aiming at producing a negative ion beam with an extracted current density in hydrogen of 355 A/m2, beam-on time of one hour. During the first 3.5 years of operation several improvements on the SPIDER source and its operating conditions were implemented. This paper focuses on the description of materials degradation phenomena in SPIDER and on the lessons learnt that were derived from components inspection during the already planned shutdown in 2022. The aim of these inspections was to improve the design of some components and to repair or refurbish damaged components. In particular, this paper describes the characterisation of damaged molybdenum coating, testing of surface cleaning techniques and experimental evidence of caesium vapour uneven distribution inside the plasma chamber. Sputtering due to beam particles was also investigated experimentally to observe its effect on materials used in SPIDER.

Status of SPIDER beam source after the first 3.5 years of operation

Agostini M;Fadone M;Spolaore M;Deambrosis S;Miorin E;Grando L;Serianni G
2023

Abstract

SPIDER is the negative ion source testbed for ITER neutral beam injector. It is currently the largest negative ion source ever built, equipped with a 100 keV accelerator, aiming at producing a negative ion beam with an extracted current density in hydrogen of 355 A/m2, beam-on time of one hour. During the first 3.5 years of operation several improvements on the SPIDER source and its operating conditions were implemented. This paper focuses on the description of materials degradation phenomena in SPIDER and on the lessons learnt that were derived from components inspection during the already planned shutdown in 2022. The aim of these inspections was to improve the design of some components and to repair or refurbish damaged components. In particular, this paper describes the characterisation of damaged molybdenum coating, testing of surface cleaning techniques and experimental evidence of caesium vapour uneven distribution inside the plasma chamber. Sputtering due to beam particles was also investigated experimentally to observe its effect on materials used in SPIDER.
2023
Istituto di Chimica della Materia Condensata e di Tecnologie per l'Energia - ICMATE
Istituto per la Scienza e Tecnologia dei Plasmi - ISTP
Neutral beam injectors
Materials degradation
Caesium
Particles interaction
Coating
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Descrizione: Status of SPIDER beam source after the first 3.5 years of operation
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Descrizione: Corrigendum to "Status of SPIDER beam source after the first 3.5 years of operation" [Fusion Engineering and Design, Volume 192, July 2023, 113831]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/460258
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