Simulation of negative hydrogen ion production and transport

Bandyopadhyay, M.; Wilhelm, R.

doi:10.1063/1.1695609

Cited by 13 publications

(7 citation statements)

References 22 publications

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“…To estimate the volume production of negative ions, we assume that 1% of H 2 molecules are excited in vibrational levels with n  4. This is in accordance with the H 2 vibrational distribution function calculated either with a 0D model [39] or a 3D particle tracking code [40]. Table 2 summarizes the collision processes of heavy ions with neutrals.…”

Section: Physical Chemistry Of Charged Particlessupporting

confidence: 81%

Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source

et al. 2017

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Negative ion sources for fusion are high densities plasma sources in large discharge volumes. There are many challenges in the modeling of these sources, due to numerical constraints associated with the high plasma density, to the coupling between plasma and neutral transport and chemistry, the presence of a magnetic filter, and the extraction of negative ions. In this paper we present recent results concerning these different aspects. Emphasis is put on the modeling approach and on the methods and approximations. The models are not fully predictive and not complete as would be engineering codes but they are used to identify the basic principles and to better understand the physics of the negative ion sources. e . (ii) A low electron temperature in the OPEN ACCESS RECEIVED

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Section: Physical Chemistry Of Charged Particlessupporting

confidence: 81%

Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source

et al. 2017

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“…Previously, numerical simulations of plasma sheaths with negative ions have been carried out for volume production using Particle In Cell (PIC) codes [12,13] and MonteCarlo transport codes [14]. On the other hand, analytic results on the plasma in the vicinity of Langmuir probes in multi-component plasmas have been published recently [15].…”

Section: Introductionmentioning

confidence: 99%

PIC code for the plasma sheath in large caesiated RF sources for negative hydrogen ions

Wünderlich¹,

Gutser²,

Fantz³

2009

Plasma Sources Sci. Technol.

101

158

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Abstract. Powerful negative hydrogen ion sources are required for heating and current drive at ITER. The physics of production and extraction of high negative ion currents is much more complex than for positive ions. One of the most relevant parameters is the shape of the plasma sheath, which determines the velocity of surface produced negative ions and thus the probability of the ions to reach the extraction system. In order to investigate the influence of hydrogen atoms, positive and negative hydrogen ions and positive caesium ions on the plasma sheath, a 1d3v PIC code for the plasma close to the extraction system has been developed. For typical plasma parameters of such ion sources, surface conversion of impinging atoms is the main negative ion production channel, while conversion of positive ions plays a minor role. Due to the formation of a potential minimum close to the surface, the emission of negative ions into the plasma is space charge limited. As a consequence, the flux of negative ions can be increased only by increasing the density of positive hydrogen ions. At identical plasma parameters, an isotope effect is determined by the mass of the particles only, resulting in lower fluxes of negative deuterium ions compared to hydrogen. A small amount of positive Cs does not change the plasma sheath and the H − flux significantly. Plasma sheath in large caesiated negative hydrogen ion sources2

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“…In a negative ion source made for NBI systems, negative ions are mainly generated by the surface production mechanism on a Cs coated low work-function surface [3]. It is a well accepted fact that negative ions which are created close (∼2 cm) to the plasma grid (PG) of the ion source are able to be extracted efficiently [4]. A detailed study of different chemical processes involved in a negative ion source and different characteristics of such source made for the NBI system can be found in [5].…”

Section: Introductionmentioning

confidence: 99%

Effect of surface produced negative ions on near wall sheath

Shah

Bandyopadhyay

2009

Plasma Phys. Control. Fusion

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The role of surface produced negative ions in a negative ion source on the sheath structure, which takes place in the surroundings of a metallic plane immersed in a plasma, is analysed using a simple model. It is well known that the Bohm criterion which determines the electric potential at the sheath edge can be multi-valued in electronegative plasmas. It is observed in this study that a multi-valued sheath potential equally holds well in the case of a negative ion source where surface production mechanism of negative ions also exists. Due to the presence of surface produced negative ions, the positive ion current flux towards the metallic plane increases and the sheath potential with respect to the metallic plane increases.

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Simulation of negative hydrogen ion production and transport

Cited by 13 publications

References 22 publications

Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source

Modeling of plasma transport and negative ion extraction in a magnetized radio-frequency plasma source

PIC code for the plasma sheath in large caesiated RF sources for negative hydrogen ions

Effect of surface produced negative ions on near wall sheath

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