Multicusp ion source with external RF antenna for production of H− ions

Kalvas, Taneli; Hahto, S. K.; Vainionpaa, J.H.; Leung, K. N.; Wilde, S.; Mandrillon, P.

doi:10.1063/1.2773654

Cited by 3 publications

(5 citation statements)

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“…Nevertheless, ion pair production could presumably enhance the volume production of negative ions in two-component discharges if the resonant excited states are populated by inelastic electron impact of photo-excitation. Kalvas et al [20] have reported that the negative ion current density extracted from an RF-driven multicusp H − ion source increased noticeably when xenon gas was introduced into the hydrogen discharge as shown in Fig. 8(a).…”

Section: On the Possibility Of Ion Pair Production In Plasma Ion Sourcesmentioning

confidence: 99%

“…In Ref. [20] the authors concluded that: "The volume production of H − is enhanced by gas mixing because the cold electron density near the extraction increases as heavier ions bring cold electrons through the magnetic filter to the low-energy plasma chamber". The given explanation contradicts the conclusion by Komppula et al arguing that volume production of D − ions in a multicusp ion source is limited by the diffusion of the heavier isotope across the transverse filter field [21].…”

Section: On the Possibility Of Ion Pair Production In Plasma Ion Sourcesmentioning

confidence: 99%

“…FIGURE 8. (a) The negative ion beam current density extracted from an RF-driven multicusp H − ion source as a function of total hydrogen and xenon pressure (the figure is reproduced from Ref [20]…”

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confidence: 99%

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Photo-assisted O− and Al− production with a cesium sputter ion source

Tarvainen

Kronholm

Laitinen

et al. 2021

Seventh International Symposium on Negative Ions, Beams and Sources (Nibs 2020)

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It has been recently proposed that the production of negative ions with cesium sputter ion sources could be enhanced by laser-assisted resonant ion pair production. We have tested this hypothesis by measuring the effect of pulsed diode lasers at various wavelengths on the O − and Al − beam current produced from Al 2 O 3 cathode of a cesium sputter ion source. The experimental results provide evidence for the existence of a wavelength-dependent photo-assisted enhancement of negative ion currents but cast doubt on its alleged resonant nature as the effect is observed for both O − and Al − ions at laser energies above a certain threshold. The beam current transients observed during the laser pulses suggest that the magnitude and longevity of the beam current enhancement depends on the cesium balance on the cathode surface. It is shown that the ions produced by the laser exposure originate from slightly different potential than the surface produced ions, which allows us to constrain the underlying physical mechanisms. It is concluded that the photo-assisted negative ion production could be of practical importance as it can more than double the extracted beam current under certain operational settings of the cesium sputter ion source. We discuss experiments designed to confirm or dispute the relevance of the ion pair production for negative ion production with cesium sputter ion sources and the possibility of ion pair production explaining the beneficial effect of xenon admixture on the negative ion yield of an RF-driven H − ion source.

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Section: On the Possibility Of Ion Pair Production In Plasma Ion Sourcesmentioning

confidence: 99%

Section: On the Possibility Of Ion Pair Production In Plasma Ion Sourcesmentioning

confidence: 99%

See 1 more Smart Citation

Photo-assisted O− and Al− production with a cesium sputter ion source

Tarvainen

Kronholm

Laitinen

et al. 2021

Seventh International Symposium on Negative Ions, Beams and Sources (Nibs 2020)

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“…Thus, several cw RF ion sources relying on volume production of -H have been developed and reported e.g. in [23,[46][47][48]. To our knowledge the first truly successful effort has taken place at Seoul National University (SNU) where the 13.56 MHz RF-driven source has produced 1.2 mA of -H in cw mode with a power efficiency of approximately 1 mA kW -1 [23,49].…”

Section: Cw Rf -mentioning

confidence: 99%

“…Additional (ongoing) improvements are, however, required as the long-term reliability of the ion source is compromized by overheating and limited voltage holding of the extraction electrodes, especially the accelerating einzel lens. Further planned developments include introducing tantalum into the surfaces of the RADIS plasma chamber and injection of small quantities of xenon gas into the discharge, which has been demonstrated to improve the -H volume production [46]. Recently the RF system developed for the RADIS ion source was coupled with the plasma chamber, magnetic filter and extraction system of the TRIUMF-type (filament) ion source [50] at the ion source test facility (ISTF) operated by D-Pace Inc. [51].…”

Section: Cw Rf -mentioning

confidence: 99%

Radiofrequency and 2.45 GHz electron cyclotron resonance H⁻volume production ion sources

Tarvainen

Peng

2016

New J. Phys.

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The volume production of negative hydrogen ions ( -H ) in plasma ion sources is based on dissociative electron attachment (DEA) to rovibrationally excited hydrogen molecules (H 2 ), which is a two-step process requiring both, hot electrons for ionization, and vibrational excitation of the H 2 and cold electrons for the -H formation through DEA. Traditionally -H ion sources relying on the volume production have been tandem-type arc discharge sources equipped with biased filament cathodes sustaining the plasma by thermionic electron emission and with a magnetic filter separating the main discharge from the -H formation volume. The main motivation to develop ion sources based on radiofrequency (RF) or electron cyclotron resonance (ECR) plasma discharges is to eliminate the apparent limitation of the cathode lifetime. In this paper we summarize the principles of -H volume production dictating the ion source design and highlight the differences between the arc discharge and RF/ECR ion sources from both, physics and technology point-of-view. Furthermore, we introduce the state-of-the-art RF and ECR -H volume production ion sources and review the challenges and future prospects of these yet developing technologies. Volume production of -HModern -H plasma ion sources rely on two ion formation processes, resonant-tunneling ionization on low work function surfaces [4] and volumetric ionization occurring in the plasma discharge [5]. Only the volume production will be discussed hereafter.

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Design and Construction the RF Ion Source for Compact Accelerator with 30 keV Energy

Janpong

2019

AMM

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In constructing the low energy accelerator for plant modification the most important part is the ion source. In the conventional cold cathodes and hot filament ion source methods the filament continuously burns out over time, has a shorter lifespan and requires venting of the ion source to atmosphere. Henceforth the Radio frequency (RF) antenna ion source or “non-thermionic ion source” with 13.6 MHz was used in the accelerator as well as it being easy to generate varie the plasma souce and stability. This ion source can produce a particle beam of about ~30 to 40 mA current. The ion particle was extracted by the first zero voltage extraction rod electrode method focusing the ion beam of 0-30 kV with the second rod electrode after which the third rod electrode has zero voltage. In calculating and designing this system via the Simion8.0 Program, the result showed that the Ar+ ion beam with 30 keV can be focused with 1 cm diameter beam at the distance of 10 cm of the drift space.

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Multicusp ion source with external RF antenna for production of H− ions

Cited by 3 publications

References 4 publications

Photo-assisted O− and Al− production with a cesium sputter ion source

Photo-assisted O− and Al− production with a cesium sputter ion source

Radiofrequency and 2.45 GHz electron cyclotron resonance H⁻volume production ion sources

Design and Construction the RF Ion Source for Compact Accelerator with 30 keV Energy

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Multicusp ion source with external RF antenna for production of H− ions

Cited by 3 publications

References 4 publications

Photo-assisted O− and Al− production with a cesium sputter ion source

Photo-assisted O− and Al− production with a cesium sputter ion source

Radiofrequency and 2.45 GHz electron cyclotron resonance H−volume production ion sources

Design and Construction the RF Ion Source for Compact Accelerator with 30 keV Energy

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Product

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Radiofrequency and 2.45 GHz electron cyclotron resonance H⁻volume production ion sources