Cesium dynamics and H− density in the extended boundary layer of negative hydrogen ion sources for fusion

Wimmer, Christian; Fantz, U.; NNBI-Team,

doi:10.1063/1.4792791

Cited by 20 publications

(22 citation statements)

References 10 publications

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“…Although the amount of extracted H − ions is not significantly changed between 0.45 Pa and 0.6 Pa, n H − is clearly increased at the higher source pressure. This dependence of n H − on the source pressure at BATMAN has been observed earlier [11,14]. A likely reason for this effect is a change in the transport of surface-produced H − into the plasma volume.…”

Section: Pressure Dependencementioning

confidence: 62%

“…The co-extracted electron current density j e shows a stronger decrease with n H − by more than a factor of four. The clear 040004-3 correlation of j H − , j e with n H − is seen regularly at BATMAN [14]. As the co-extracted electron current density reacts very sensitive on the PG bias, the influence of varying the bias voltage has been investigated in more detail.…”

Section: Source Performance and N H − During The Cs Conditioning Phasementioning

confidence: 99%

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Dependence of the source performance on plasma parameters at the BATMAN test facility

2015

AIP Conference Proceedings

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Section: Pressure Dependencementioning

confidence: 62%

Section: Source Performance and N H − During The Cs Conditioning Phasementioning

confidence: 99%

Dependence of the source performance on plasma parameters at the BATMAN test facility

2015

AIP Conference Proceedings

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“…In the second case the negative ion density in the bulk plasma region was measured with the same diagnostic (cavity ring-down spectroscopy) but it was installed above the center of the plasma grid again a few cm downstream from its surface - Fig. 1, right (more details can be found in [28]). The measurements corresponding to this configuration are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Comparison of ONIX simulation results with experimental data from the BATMAN testbed for the study of negative ion extraction

et al. 2016

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The development of negative ion (NI) sources for the ITER neutral beam injector is strongly accompanied by modelling activities. The ONIX (Orsay Negative Ion eXtraction) code simulates the formation and extraction of negative hydrogen ions and co-extracted electrons produced in caesiated sources. The 3D geometry of the BATMAN extraction system and the source characteristics such as the extraction and bias potential, 3D magnetic field were integrated in the model. Calculations were performed using plasma parameters experimentally obtained on BATMAN. Comparison of the ONIX calculated extracted NI density with experimental results suggests that predictive calculations of the extraction of negative ions are possible. The results show that for an ideal status of the Cs conditioning the extracted hydrogen NI current density could reach about ~30 mAcm -2 at 10 kV and about ~20 mAcm -2 at 5 kV extraction potential with an electron/NI current density ratio of about 1, as measured in the experiments under the same plasma and source conditions. The dependency of the extracted NI current on the negative ion density in the bulk plasma region from both the modeling and the experiment was investigated. The separate distributions composing the negative ion beam originating from the plasma bulk region and the PG surface are presented for different NI plasma volume densities and NI emission rates from the plasma grid wall respectively. The extracted current from NI produced at the Cs covered plasma grid (PG) surface, initially moving towards the bulk plasma and then being bent towards the extraction surfaces is lower compared to the extracted NI current from directly extracted surface produced ions.

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“…This value is much larger than the results of the 1d PIC code Bacon [37] but smaller compared to other 3d PIC codes [40]). Consequently, the negative ion density in the plasma volume is rather low (up to 10 16 m −3 , mainly produced by volume production) while at BATMAN using cavity ring-down spectroscopy (CRDS) line-of-sight integrated negative ion densities of up to 10 17 m −3 (depending on the RF power and filling pressure) have been measured in 2.2 cm distance from the PG [51].…”

Section: The Code Onix and Its Resultsmentioning

confidence: 99%

Modelling the ion source for ITER NBI: from the generation of negative hydrogen ions to their extraction

Wünderlich

Mochalskyy

Fantz

et al. 2014

Plasma Sources Sci. Technol.

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Abstract. The neutral beam injection system for ITER is based on a large (A source = 1.9 × 0.9 m 2 ) negative hydrogen or deuterium ion source. In this source negative ions are produced in a low-pressure (p fill ≈ 0.3 Pa) plasma by conversion of atoms and protons on a caesiated molybdenum surface with low work function. Then the negative ions are transported through the plasma to the extraction system where extraction of these ions and also co-extraction of electrons take place. This paper describes the status of the modeling activities connected with the negative ion test facilities of IPP Garching. It is illustrated that these modelling activities constitute a strong support of the experimental activities connected with the development of the negative ion source for ITER NBI. Several numerical codes developed in the past years -in close collaboration with the experiment -and their results are introduced. Focus is laid on the production, transport and extraction of negative hydrogen ions and on the inevitable co-extraction of electrons. Size scaling from the IPP prototype source to the ion source of the ELISE test facility to the full negative ion source for ITER NBI. Modeling the ion source for ITER NBI

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Cesium dynamics and H− density in the extended boundary layer of negative hydrogen ion sources for fusion

Cited by 20 publications

References 10 publications

Dependence of the source performance on plasma parameters at the BATMAN test facility

Dependence of the source performance on plasma parameters at the BATMAN test facility

Comparison of ONIX simulation results with experimental data from the BATMAN testbed for the study of negative ion extraction

Modelling the ion source for ITER NBI: from the generation of negative hydrogen ions to their extraction

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