Time resolved experiments at the Frankfurt 14 GHz electron cyclotron resonance ion source

Runkel, S.; Höhn, Oliver; Stiebing, K. E.; Schempp, A.; Schmidt‐Böcking, H.; Миронов, В. И.; Shirkov, G.

doi:10.1063/1.1150343

Cited by 17 publications

(8 citation statements)

References 2 publications

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“…Currents of the highly charged ions above 6+ charge state drop noticeably, while currents of the moderately and lowly charged ions are not affected. Changes in the source output are consistent with the experimental observations [15,16].…”

Section: The Biased Electrode Effectsupporting

confidence: 87%

Spatial distributions of plasma potential and density in electron cyclotron resonance ion source

Mironov

Bogomolov

Bondarchenko

et al. 2020

Plasma Sources Sci. Technol.

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The Numerical Advanced Model of Electron Cyclotron Resonance Ion Source (NAM-ECRIS) is applied for studies of the physical processes in the source. Solutions of separately operating electron and ion modules of NAM-ECRIS are matched in iterative way such as to obtain the spatial distributions of the plasma density and of the plasma potential. Results reveal the complicated profiles with the maximized plasma density close to the ECR surface and on the source axis. The ion-trapping potential dips are calculated to be on the level of ~(0.01-0.05) V being located at the plasma density maxima. The highly charged ions are also localized close to the ECR surface. The biased electrode effect is due to an "electron string" along the source axis formed by reflection of electrons from the biased electrode and the extraction aperture. The string makes profiles of the highly charged ions more peaked on the source axis, thus increasing the extracted ion currents.

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Section: The Biased Electrode Effectsupporting

confidence: 87%

Spatial distributions of plasma potential and density in electron cyclotron resonance ion source

Mironov

Bogomolov

Bondarchenko

et al. 2020

Plasma Sources Sci. Technol.

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“…Similar tests to those described in this paper have resulted in ion current improvements for ECR ion sources operating in pulsed or CW mode [4,5]. For the CERN source operating in afterglow mode, no significant current increases have been observed in any of these or previous experiments [7,8,11].…”

Section: Conclusion and Discussionmentioning

confidence: 50%

“…Recent investigations, on the other hand, suggest that the ion yield increase be mainly due to improved extraction conditions [4] or plasma potential optimisation [5].…”

Section: Tests and Results With Biased Axial Electrodementioning

confidence: 99%

Effect of a biased probe on the afterglow operation of an ECR4 ion source

Hill

Küchler

Wenander

et al. 2000

Review of Scientific Instruments

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Various experiments have been performed on a 14.5 GHz ECR4 in order to improve the ion yield. The source runs in pulsed afterglow mode, and provides currents 120 ePA of Pb 27+ to the CERN Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings.No proof for absolute higher intensities was seen for any of these modifications. However, the yield from a poorly tuned/low-performing source could be improved and the extracted pulse was less noisy with bias voltage applied. The fast response on the bias implies that increases/decreases are not due to ionisation processes. A good tune for high yield of high charge states during the afterglow coincides with a high plasma potential. '99, Kyoto, Japan, September 6-10, 1999 Geneva Abstract Various experiments have been performed on a 14.5 GHz ECR4 in order to improve the ion yield. The source runs in pulsed afterglow mode, and provides currents ~120 ePA of Pb 27+ to the CERN Heavy Ion Facility on an operational basis. In the search for higher beam intensities, the effects of a pulsed biased disk on axis at the injection side were investigated with different pulse timing and voltage settings. Paper presented at the 8th International Conference on Ion sources, ICISNo proof for absolute higher intensities was seen for any of these modifications. However, the yield from a poorly tuned/low-performing source could be improved and the extracted pulse was less noisy with bias voltage applied. The fast response on the bias implies that increases/decreases are not due to ionisation processes. A good tune for high yield of high charge states during the afterglow coincides with a high plasma potential.

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“…In particular, since the ion distribution in the plasma is closely related to the electron distribution ͑quasineutrality͒ large electron densities in the center of the extraction opening will dynamically confine ions to this area and serve to extract higher ion currents ͑"biased disk effect"͒. 9 In order to elucidate the role of this contribution, we have carried out a new experiment, where the extraction electrode of the Frankfurt 14 GHz ECRIS was covered with a high-emissive MD structure. The dielectric layer is faced towards the plasma; the extraction hole of the layer is only slightly larger than the hole of the plasma electrode ͑+0.5 mm͒ to avoid alignment problems.…”

Section: Introductionmentioning

confidence: 99%

Improved ion extraction from an electron cyclotron resonance ion source by a metal-dielectric-extraction electrode

Schächter

Dobrescu

Stiebing

2006

Review of Scientific Instruments

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The goal of the experiment was to study the influence and the physics of the boundary region ͑between the plasma and the extraction potential͒ with direct impact on the source ion-beam output. A specially processed high-emissive metal-dielectric structure was installed on the extraction electrode of the Frankfurt 14 GHz electron cyclotron resonance ion source ͑ECRIS͒, forming a so-called metal-dielectric-͑MD͒ extraction electrode. The emissive layer of the disk faced the plasma; its inner hole was about the size of the normal extraction hole of the ECRIS. The output of the ECRIS in the presence of the MD electrode was compared with the outputs for the standard configuration ͑overall stainless-steel plasma chamber͒ and with the same plasma chamber with the radial wall covered by a highly electron emissive MD liner that raise the plasma electron density and temperature. The charge state distributions of the argon ions extracted from the source show an important increase of the ion beam for the high charge states as compared to the standard situation whereas the low charge states are less reduced than in the case of the presence of a MD liner. Due to the special position of the dielectric layer, the MD electrode introduces a new effect, which is connected to its property of becoming a positively charged surface under electron and ion bombardment. The MD electrode creates a quasiconfinement of the peripheral ions in the extraction, those ions that are normally lost to a conducting extraction electrode.

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Time resolved experiments at the Frankfurt 14 GHz electron cyclotron resonance ion source

Cited by 17 publications

References 2 publications

Spatial distributions of plasma potential and density in electron cyclotron resonance ion source

Spatial distributions of plasma potential and density in electron cyclotron resonance ion source

Effect of a biased probe on the afterglow operation of an ECR4 ion source

Improved ion extraction from an electron cyclotron resonance ion source by a metal-dielectric-extraction electrode

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