Cesium mixing in the multi-ampere volume H− ion source

Okumura, Y.; Hanada, M.; Inoue, Takashi; Kojima, Hiroaki; Matsuda, Yoshinori; Ohara, Y.; Seki, Masanori; Watanabe, K.

doi:10.1063/1.39587

Cited by 57 publications

(22 citation statements)

References 1 publication

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“…Figure 3 shows the beam current as a function of the temperature of the plasma grid during long pulse operations with three magnitudes of arc power, namely, 180 kW, 190 kW and 200 kW. This result is consistent with the basic data obtained in the small ion sources, where the optimum plasma grid temperature was 250 300°C for the cesium effect [7]. …”

Section: Ialsupporting

confidence: 87%

Recent Activities of Negative Ion Based NBI System on JT-60U

Ebisawa¹,

Akino²,

Grisham

et al. 2005

21st IEEE/NPS Symposium on Fusion Engineering SOFE 05

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The pulse duration of the negative ion based NBI system has been extended from 10 s to 25 s to study long pulse plasmas on JT-60U. A feedback control technique has been demonstrated to keep the arc power constant by controlling the filament voltage for long pulse operation. Thus it was clearly observed that the negative ion beam current increased with the temperature of the plasma grid at constant arc power. A tapered filament is employed to improve its durability for the next operational campaign. Moreover, a high voltage holding test indicates that the reduction in the outgassing from the FRP (fiberglass-reinforced plastic) insulator may be a key to suppress the breakdowns in the ion source.

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Section: Ialsupporting

confidence: 87%

Recent Activities of Negative Ion Based NBI System on JT-60U

Ebisawa¹,

Akino²,

Grisham

et al. 2005

21st IEEE/NPS Symposium on Fusion Engineering SOFE 05

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“…244 The large input power to sustain an arc discharge elevated the temperature of the plasma grid and increased the H À ion current due to the higher temperature of Cs coated plasma grid. The grid temperature control allowed obtaining H À ion beam current as large as 3.3 A from a Cs seeded ion source with 25 cm Â 25 cm extraction area.…”

Section: B Cs Seeded Source Operation For Fusion Experiments and Accmentioning

confidence: 99%

Negative hydrogen ion production mechanisms

Bacal

Wada

2015

Applied Physics Reviews

239

173

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International audienceNegative hydrogen/deuterium ions can be formed by processes occurring in the plasma volume and on surfaces facing the plasma. The principal mechanisms leading to the formation of these negative ions are dissociative electron attachment to ro-vibrationally excited hydrogen/deuterium molecules when the reaction takes place in the plasma volume, and the direct electron transfer from the low work function metal surface to the hydrogen/deuterium atoms when formation occurs on the surface. The existing theoretical models and reported experimental results on these two mechanisms are summarized. Performance of the negative hydrogen/deuterium ion sources that emerged from studies of these mechanisms is reviewed. Contemporary negative ion sources do not have negative ion production electrodes of original surface type sources but are operated with caesium with their structures nearly identical to volume production type sources. Reasons for enhanced negative ion current due to caesium addition to these sources are discussed. (31 pages, 265 refs

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“…In volume production, a highly vibrationally excited hydrogen molecule effectively captures a low-energy plasma electron to form a negative ion through dissociative electron attachment. [9][10][11][12][13] However, there is a relatively low current density of negative ions in volume production.…”

Section: Introductionmentioning

confidence: 99%

Separation of ion components produced by plasma-assisted catalytic ionization

Oohara

Hibino

Higuchi

et al. 2012

Review of Scientific Instruments

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Formation of negative hydrogen ion: Polarization electron capture and nonthermal shielding J. Chem. Phys. 137, 094310 (2012) Ionization energy of atoms obtained from GW self-energy or from random phase approximation total energies J. Chem. Phys. 136, 194107 (2012) Scattering of nitrogen molecules by silver atoms J. Chem. Phys. 136, 164305 (2012) Rotational excitation of H2O by para-H2 from an adiabatically reduced dimensional potential J. Chem. Phys. 136, 094109 (2012) Additional information on Rev. Sci. Instrum. Positive and negative hydrogen ions are produced by plasma-assisted catalytic ionization using a porous nickel plate, where the irradiation current density and energy of positive ions produced by discharge to the porous plate are controlled. The ion energy distributions are analyzed from the properties of current densities of positive and negative ions extracted from the porous surface. Positive ions passing through fine pores of the porous plate and positive and negative ions produced on the porous surface are observed. It is clarified that the produced fluxes of positive and negative ions and the flux balance between them are controlled by the irradiation current density and energy, respectively.

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Cesium mixing in the multi-ampere volume H− ion source

Cited by 57 publications

References 1 publication

Recent Activities of Negative Ion Based NBI System on JT-60U

Recent Activities of Negative Ion Based NBI System on JT-60U

Negative hydrogen ion production mechanisms

Separation of ion components produced by plasma-assisted catalytic ionization

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