High density negative hydrogen ion production in a high power pulsed helicon discharge

Santoso, Jesse; Willett, Hannah V.; Corr, Cormac

doi:10.1088/1361-6595/aae705

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…a medium size tokamak, T-15MD is under construction at Kurchatov Institute in Moscow, Russia [6] a spherical tokamak GLOBUS-M2 is under construction at Ioffe Physical-Technical Institute in St. Petersbourg, Russia [7] the Australian Plasma Fusion Research Facility (APFRF) upgraded the H-1Heliac, a large stellarator device located at ANU (Australian National University) in Canberra, called H-1NF [8] and research is conducted for producing negative ion beams using a high-power helicon discharge source [9]. -The Broader Approach agreement, concluded between the European Atomic Energy Community (Euratom) and Japan, consists of activities which aim to complement the ITER project and to accelerate the realization of fusion energy through R&D and advanced technologies for future demonstration of fusion power reactors (DEMO).…”

Section: Introductionmentioning

confidence: 99%

Negative ion source operation with deuterium

Bacal

Wada

2020

Plasma Sources Sci. Technol.

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When the working gas of a negative ion source is changed from hydrogen to its isotope, deuterium, an ‘isotope effect’ is observed; namely, several plasma characteristics such as the electron energy distribution, the atomic fraction and the spectra of rovibrationally excited molecules change. The understanding of the effect becomes more important, as research and development aiming at ITER power level operation is being challenged with feeding deuterium to the ion sources. As a historical review of the effort to develop hydrogen/deuterium negative ion sources, several types of negative ion sources designed for the neutral beam plasma heating are described: double charge exchange sources, volume sources and surface-plasma sources. The early results with volume sources operated with and without cesium are introduced. The characteristics of the source charged with deuterium are compared to those of the source charged with hydrogen. The isotope effect did not appear pronounced as the negative ion density was measured in a small source but became more pronounced when the plasma source size was enlarged and the discharge power density was increased to higher values. Surface plasma sources were optimized for deuterium operation but could not achieve the same performance as a source operated with hydrogen at the same power and pressure. The lower velocity of negative deuterium ions leaving the low work function surface seemed to limit the production efficiency. Fundamental processes causing these differences in negative ion source operation are summarized. After explaining the current status of negative ion source research and development, the acquired knowledge is utilized to the development of large negative ion sources for nuclear fusion research and to the development of compact negative ion sources for neutron source applications.

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Section: Introductionmentioning

confidence: 99%

Negative ion source operation with deuterium

Bacal

Wada

2020

Plasma Sources Sci. Technol.

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“…In recent years, the possibility of producing negative ions (H − or D − ) for HNB injectors by means of helicon plasma sources has been investigated at the resonant antenna ion device (RAID) experiment [6,7]. In parallel, other helicon plasma sources operating worldwide have studied the volume production of negative ions in helicon-sustained plasmas [8][9][10][11]. In RAID, plasmas are sustained by a resonant birdcage antenna used as a helicon plasma source [12] for up to 10 kW long-pulse operation.…”

Section: Introductionmentioning

confidence: 99%

A 1.5D fluid—Monte Carlo model of a hydrogen helicon plasma

Agnello

Fubiani

Furno

et al. 2022

Plasma Phys. Control. Fusion

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Helicon plasma sources operating with hydrogen or deuterium might be attractive for fusion applications due to their higher power efﬁciency compared to inductive radiofrequency plasma sources. During recent years, the Resonant Antenna Ion Device (RAID) has been investigating the physics of helicon plasmas and the possibility of employing them to produce negative ions for Heating Neutral Beam injectors (HNBs). We present herein a ﬂuid-Monte Carlo model describing plasma species transport of a typical helicon hydrogen plasma discharge. This work is motivated by the interest to better understand the basic physics of helicon plasma devices when operating in hydrogen and, in particular, the volume production of negative ions. This model is based on the synergy between two separately self-consistent approaches: a plasma ﬂuid model calculating ion transport, and a Monte Carlo (MC) model, to determine neutral and rovibrational density proﬁles of H2. By introducing as model constraints the electron density and temperature proﬁles measured by Langmuir Probes, the densities of ion species (H+, H2+ , H3+ , H−) are computed in a 1.5D (dimensional) geometry. The estimate of the negative ion density proﬁle represents a useful benchmark to be compared with dedicated diagnostics such as Cavity Ring-Down Spectroscopy and Langmuir probe laser photodetachment. Neutral gas particles (atoms and molecules) are calculated assuming a ﬁxed plasma background. This gas-plasma decoupling is necessary due to the different timescales of plasma (microseconds) and gas kinetics (milliseconds).

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“…The measurements presented in this work were obtained in the MAGnetised plasma interaction experiment (MAGPIE) helicon device (figure 1) at The Australian National University which has been described in detail previously [19]. The MAGPIE device has previously been used to study a number of hydrogen-based plasmas for negative ion production [20], gas heating [21], and ammonia formation [22]. The MAGPIE device consists of two chambers: a 1 m long, 10 cm diameter borosilicate source chamber which is connected to 68 cm long stainless steel target chamber.…”

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confidence: 99%

Depletion of atomic hydrogen in a high power helicon discharge

Cousens

Santoso

Corr

2020

Plasma Sources Sci. Technol.

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Depletion of the ground state atomic hydrogen density has been directly measured using two-photon laser-induced fluorescence in a high-density helicon plasma. The depletion is correlated with the plasma pressure becoming increasingly higher than the neutral gas fill pressure. Spatially resolved measurements show depletion of atomic hydrogen in the centre of the discharge chamber. Temporally resolved measurements display a replenishment of atomic hydrogen in the plasma afterglow at high plasma densities in comparison to the typical two-step decay at lower plasma densities.

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High density negative hydrogen ion production in a high power pulsed helicon discharge

Cited by 5 publications

References 30 publications

Negative ion source operation with deuterium

Negative ion source operation with deuterium

A 1.5D fluid—Monte Carlo model of a hydrogen helicon plasma

Depletion of atomic hydrogen in a high power helicon discharge

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