Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Wünderlich, D.; Dietrich, Scott; Fantz, U.

doi:10.1016/j.jqsrt.2008.09.015

Cited by 77 publications

(65 citation statements)

References 30 publications

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“…As discharge parameters especially the electron density (as measure for the integrated density of the positive hydrogen ions) and the density ratio of atomic to molecular hydrogen n H /n H 2 (as measure for the atomic hydrogen density) are important with respect to the H − production in ion sources [4]. Therefore these parameters and the electron temperature have been determined from the absolute emission of the Balmer lines and the molecular Fulcher emission via applying the collisional radiative models Yacora H for atomic [12] and Yacora H 2 for molecular hydrogen [13,14].…”

Section: Helicon Couplingmentioning

confidence: 99%

Alternative RF coupling configurations for H− ion sources

Briefi

Gutmann

Fantz

2015

AIP Conference Proceedings

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Abstract. RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H − current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been set up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region.

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Section: Helicon Couplingmentioning

confidence: 99%

Alternative RF coupling configurations for H− ion sources

Briefi

Gutmann

Fantz

2015

AIP Conference Proceedings

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“…[10], were interpreted using the collisional-radiative code YACORA [11] , together with the electron density n e and temperature T e . Figure 5 shows the radial profiles of (a) the dissociation degree, and of (b) the H -density estimated by YACORA 68 cm away from the birdcage antenna in a H 2 plasma with 3.5 kW of RF power.…”

Section: Epj Web Of Conferencesmentioning

confidence: 99%

Helicon wave-generated plasmas for negative ion beams for fusion

et al. 2017

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Abstract. In the next generation of fusion reactors, such as DEMO, neutral beam injectors (NBIs) of high energy (0.8-1 MeV) deuterium atoms with high wall-plug efficiency (>50%) will be required to reach burning plasma conditions and to provide a significant amount of current drive. The present NBI system for DEMO assumes that 50 MW is delivered to the plasma by 3 NBIs. In the Siphore NBI concept, negative deuterium ions are extracted from a long, thin ion source 3 m high and 15 cm wide, accelerated and subsequently photo-neutralized. This requires the development of a new generation of negative ion sources. At the Swiss Plasma Center, a novel radio frequency helicon plasma source, based on a resonant network antenna source delivering up to 10 kW at 13.56 MHz, has been developed and is presently under study on the Resonant Antenna Ion Device (RAID). RAID is a linear device (1.9 m total length, 0.4 m diameter) and is equipped with an extensive set of diagnostics for full plasma characterization. In this work, the principles of operation of resonant antennas as helicon sources are introduced. We present absolute spectroscopy, Langmuir probe, and interferometry measurements on helicon plasmas. We characterize the performance of the source in terms of hydrogen/deuterium dissociation and negative ion production as a function of the input power. Furthermore, first results with the helicon birdcage antenna installed on the Cybele negative ion source at CEA-IRFM are presented, as a first step towards the validation of the Siphore concept.

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“…The effective rate coefficient is taken directly from Ref. 26 . For the Ar atom the line at 750.4 nm is used because this line is also predominantly excited by direct excitation from the ground state 27 .…”

Section: B Optical Emission Spectroscopymentioning

confidence: 99%

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H2-Ar low-pressure plasmas

Sode

Schwarz-Selinger

Jacob

et al. 2014

Journal of Applied Physics

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In an inductively-coupled H 2 -Ar plasma at a total pressure of 1.5 Pa the influence of the electrode cover material on selected line intensities of H, H 2 , and Ar are determined by optical emission spectroscopy and actinometry for the electrode cover materials stainless steel, copper, tungsten, Macor , and aluminum. Hydrogen dissociation degrees for the considered conditions are determined experimentally from the measured emission intensity ratios. The surface loss probability β H of atomic hydrogen is correlated with the measured line intensities and β H values are determined for the considered materials. Without the knowledge of the atomic hydrogen temperature, β H cannot be determined exactly. However, ratios of β H values for different surface materials are in first order approximation independent of the atomic hydrogen temperature. Our results show that β H of copper is equal to the value of stainless steel, β H of Macor and tungsten is about 2 times smaller and β H of aluminum about 5 times smaller compared with stainless steel. The latter ratio is in reasonable agreement with literature. The influence of the atomic hydrogen temperature T H on the absolute value is thoroughly discussed. For our assumption of T H = 600 K we determine a β H for stainless steel of 0.39 ± 0.13.

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Application of a collisional radiative model to atomic hydrogen for diagnostic purposes

Cited by 77 publications

References 30 publications

Alternative RF coupling configurations for H− ion sources

Alternative RF coupling configurations for H− ion sources

Helicon wave-generated plasmas for negative ion beams for fusion

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H2-Ar low-pressure plasmas

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