Characterization of the SPIDER Cs oven prototype in the CAesium Test Stand for the ITER HNB negative ion sources

Rizzolo, A.; Barbisan, M.; Bizzotto, Luisa; Capobianco, R.; Muri, M. De; Fadone, M.; Ghiraldelli, R.; Gorno, S.; Laterza, B.; Marchiori, G.; Marcuzzi, D.; Migliorato, Luisa; Molon, F.; Ravarotto, D.; Rizzieri, R.; Rossetto, F.; Sartori, E.; Serianni, G.; Veltri, P.

doi:10.1016/j.fusengdes.2019.01.053

Cited by 21 publications

(15 citation statements)

References 11 publications

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“…The High Voltage RadioFrequency Test Facility (HVRFTF) [24] is devoted to the characterisation of the dielectric strength in vacuum of the RF drivers to address potential issues of voltage holding of beam source components under RF electric fields at low gas pressure. In the CAesium Test Stand (CATS) [25] the characterisation of the caesium ovens before installation into SPIDER and MITICA is performed, in terms of diagnostics, oven maintenance and caesium management [26]. The High Voltage Padova Test Facility (HVPTF) [27] aims at performing optimised experiments of voltage holding up to 1MV in vacuum and with gas, with tight control of voltage, current, pressure and vacuum quality.…”

Section: Accompanying Programmementioning

confidence: 99%

SPIDER in the roadmap of the ITER neutral beams

Serianni

Toigo

Bigi

et al. 2019

Fusion Engineering and Design

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To reach fusion conditions and control plasma configuration in ITER, a suitable combination of additional heating and current drive systems is necessary. Among them, two Neutral Beam Injectors (NBI) will provide 33MW hydrogen/deuterium particles electrostatically accelerated to 1MeV; efficient gas-cell neutralisation at such beam energy requires negative ions, obtained by caesium-catalysed surface conversion of atoms inside the ion source. As ITER NBI requirements have never been simultaneously attained, a Neutral Beam Test Facility (NBTF) was set up at Consorzio RFX (Italy), including two experiments. MITICA is the full-scale NBI prototype with 1MeV particle energy. SPIDER, with 100keV particle energy, aims at testing and optimising the full-scale ion source: extracted beam uniformity, negative ion current density (for one hour) and beam optics (beam divergence <7mrad; beam aiming direction within 2mrad). This paper outlines the worldwide effort towards the ITER NBI realisation: the main results of the ELISE facility (IPP-Garching, Germany), equipped with a half-size source, are described along with the status of MITICA; specific issues are investigated by small specific facilities and by joint experiments at QST and NIFS (Japan). The SPIDER experiment, just come into operation, will profit from strong modelling activities, to simulate and interpret experimental scenarios, and from advanced diagnostic instruments, providing thorough plasma and beam characterisation. Finally, the results of the first experiments in SPIDER are presented, aimed at a preliminary source plasma characterisation by plasma light detectors and plasma spectroscopy.

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Section: Accompanying Programmementioning

confidence: 99%

SPIDER in the roadmap of the ITER neutral beams

Serianni

Toigo

Bigi

et al. 2019

Fusion Engineering and Design

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“…The main components are highlighted, and the oven is very similar to the one applied at ELISE. The ovens for SPIDER are described in details in [11] and [13], and they are briefly described in the following, focusing on the differences to the ELISE ovens.…”

Section: Comparison To Elise Ovenmentioning

confidence: 99%

“…In this way, direct evaporation of Cs towards the plasma grid is avoided, and Cs will be probably mostly evaporated towards the back-plate and the sidewalls, as shown in Figure 2b. The oven is equipped with an oven SID, whose filaments surround the lateral surface of the nozzle where the orifices are located [11].…”

Section: Comparison To Elise Ovenmentioning

confidence: 99%

“…The very first investigations of the SPIDER oven were performed at the dedicated test stand CATS, which is described in detail in [11]. CATS consists of a stainless steel vessel, shown in Figure 3a, separated in two volumes by a stainless steel diaphragm resembling the back-plate of the SPIDER ion source.…”

Section: First Tests Of the Spider Ovenmentioning

confidence: 99%

“…Contrarily to ELISE, the SPIDER source is fully in vacuum (as for ITER), including the ovens, hence a new oven design was required. The ovens have been recently manufactured and first tests have been performed at the dedicated laboratory experiment CATS (CAesium Test Stand) at Consorzio RFX [11].…”

Section: Introductionmentioning

confidence: 99%

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Design and comparison of the Cs ovens for the test facilities ELISE and SPIDER

Cristofaro

Fröschle

Mimo

et al. 2019

Review of Scientific Instruments

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Negative ion sources for fusion rely on the formation of negative hydrogen (or deuterium) ions by conversion of atomic hydrogen and positive hydrogen ions at a low work function caesiated surface. Cs is thus evaporated into the source to decrease the surface work function, which may change due to the removal and redistribution of Cs during plasma phases. To maintain a temporarily stable low work function during one hour plasma, continuous evaporation of caesium is required, and this is performed by temperature controlled Cs ovens. The Cs ovens for ELISE (IPP Garching) and SPIDER (Consorzio RFX) are based on the evaporation of liquid Cs from a reservoir located at one end of the oven, and the evaporation of Cs is controlled by the reservoir temperature. The ampoule Cs oven of ELISE is in operation since 2015, allowing for controllable and stable evaporation. The SPIDER oven is based on the ELISE oven, though it required significant changes due to the vacuum environment and the oven location (at the back-plate instead of the sidewalls), leading to a different design of the oven and the nozzle. First investigations on the SPIDER oven in a dedicated test stand show that Cs evaporation is controllable, stable and reproducible.

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