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

Mironov, V. E.; Bogomolov, S. L.; Bondarchenko, A. E.; Ефремов, А. А.; Loginov, V. N.; Pugachev, D.

doi:10.1088/1361-6595/ab62dc

Cited by 13 publications

(17 citation statements)

References 25 publications

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“…The density profile is almost uniform inside the ECR volume, with formation of the small local density maxima close to the ECR surface for the largest gas flow. These maxima are much less pronounced in comparison to what had been reported in our previous publication [4], where the electron dynamics was calculated in assumption that electrons do not interact with microwaves inside the ECR volume.…”

Section: Modelling Of the Electron Dynamicscontrasting

confidence: 71%

“…The ECR positions are labeled with the dashed lines. The field amplitudes close to the resonance are at the level of ~10 4 V/m and decrease by a factor of 2 inside the ECR zone. Standing wave patterns are seen both inside and outside the zone regions.…”

Section: Modelling Of the Microwave Propagation In The Source Plasmamentioning

confidence: 95%

“…To understand the mechanism of source performance saturation with the increased gas flow (plasma density), we perform numerical simulations of processes in ECRIS by using the NAM-ECRIS (Numerical Advanced Model of Electron Cyclotron Resonance Ion Source) group of codes. The model is extensively described elsewhere [4]. The major modifications in the current version are made in the parts concerning calculations of the electron dynamics.…”

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confidence: 99%

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Three-dimensional modelling of processes in Electron Cyclotron Resonance Ion Source

Mironov¹,

Bogomolov²,

Bondarchenko³

et al. 2020

J. Inst.

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Three-dimensional numerical model is developed and applied for studies of physical processes in Electron Cyclotron Resonance Ion Source. The model includes separate modules that simulate the electron and ion dynamics in the source plasma in an iterative way. The electron heating by microwaves is simulated by using results of modelling the microwave propagation in the plasma by the COMSOL Multiphysics ® software. Extracted ion currents and other parameters of the source are obtained for different gas flows into the source. It is observed that the currents are strongly influenced by ion transport in transversal direction induced by the plasma potential gradients. Impact of some special techniques on the source performance is investigated. Magnetic field scaling is shown to reduce the ion losses during their movement toward the extraction aperture, as well as use of the aluminum chamber walls and mixing of the working gas with helium. 1 The data that support the findings of this study are available from the corresponding author upon reasonable request.

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Section: Modelling Of the Electron Dynamicscontrasting

confidence: 71%

Section: Modelling Of the Microwave Propagation In The Source Plasmamentioning

confidence: 95%

mentioning

confidence: 99%

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Three-dimensional modelling of processes in Electron Cyclotron Resonance Ion Source

Mironov¹,

Bogomolov²,

Bondarchenko³

et al. 2020

J. Inst.

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“…The spatial distribution of hot electrons in ECRIS plasmas has been studied both numerically and experimentally [34][35][36] and it has been concluded that the majority of the plasma energy content is carried by the electron population in the dense plasmoid surrounded by the ECR surface. As the instabilities are driven by the local EED, it could be argued that the volume by the resonance zone therefore affects the B min at the instability threshold.…”

Section: Discussionmentioning

confidence: 99%

Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma

et al. 2022

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Electron Cyclotron Resonance (ECR) ion source plasmas are prone to kinetic instabilities. The onset of the instabilities manifests as emission of microwaves, bursts of electrons expelled from the plasma volume, and the collapse of the extracted highly charged ion (HCI) currents. Consequently, the instabilities limit the HCI performance of ECR ion sources by limiting the parameter space available for ion source optimization. Previous studies have shown that the transition from stable to unstable plasma regime is strongly influenced by the magnetic field structure, especially the minimum field value inside the magnetic trap (B min ). This work focuses to study the role of the magnetic confinement on the onset of the kinetic instabilities by probing the influence of the injection and extraction mirror field variation on the instability threshold. The experiments have been performed with a room-temperature 14.5 GHz ECR ion source with an axially movable middle coil that provides flexible control over the axial field profile and especially the B min , which was used to quantify the variation in the instability threshold. The experimental results show that variation of the extraction field B ext , which defines the weakest magnetic mirror, correlates systematically with the variation of the instability threshold; decreasing the B ext allows higher threshold B min . The result demonstrates the importance of electron confinement and losses on the plasma stability. The connection between the weakest mirror field and the onset of instabilities is discussed taking into account the variation of magnetic field gradient and resonance plasma volume.

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“…As a consequence, they obtained a great degree of match between predicted and measured steady-state CSD and were able to analyze various aspects of ECRIS operation such as neutral density gradient and isotope anomaly effect. In later works, they extended their analysis to include multicomponent, localized electron energy distribution functions and investigated the ion confinement processes in the plasma [20] and then applied their algorithms to investigate the behavior of the device with different working materials [21]. The local neutrality assumption was dropped by coupling an electron simulation code NAM-ECRIS(e) with its ion counterpart NAM-ECRIS(i), effectively modeling electron and ion evolution simultaneously in the plasma [22].…”

Section: Ecr Simulation Models: a Reviewmentioning

confidence: 99%

Modeling space-resolved ion dynamics in ECR plasmas for predicting in-plasma β-decay rates

et al. 2022

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Lifetimes of radioactive nuclei are known to be affected by the level configurations of their respective atomic shells. Immersing such isotopes in environments composed of energetic charged particles such as stellar plasmas can result in β-decay rates orders of magnitude different from those measured terrestrially. Accurate knowledge of the relation between plasma parameters and nuclear decay rates are essential for reducing uncertainties in present nucleosynthesis models, and this is precisely the aim of the PANDORA experiment. Currently, experimental evidence is available for fully stripped ions in storage rings alone, but the full effect of a charge state distribution (CSD) as exists in plasmas is only modeled theoretically. PANDORA aims to be the first to verify these models by measuring the β-decay rates of select isotopes embedded in electron cyclotron resonance (ECR) plasmas. For this purpose, it is necessary to consider the spatial inhomogeneity and anisotropy of plasma ion properties as well as the non-local thermodynamic equilibrium (NLTE) nature of the system. We present here a 3D ion dynamics model combining a quasi-stationary particle-in-cell (PIC) code to track the motion of macroparticles in a pre-simulated electron cloud while simultaneously using a Monte Carlo (MC) routine to check for relevant reactions describing the ion population kinetics. The simulation scheme is robust, comprehensive, makes few assumptions about the state of the plasma, and can be extended to include more detailed physics. We describe the first results on the 3D variation of CSD of ions both confined and lost from the ECR trap, as obtained from the application of the method to light nuclei. The work culminates in some perspectives and outlooks on code optimization, with a potential to be a powerful tool not only in the application of ECR plasmas but for fundamental studies of the device itself.

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

Cited by 13 publications

References 25 publications

Three-dimensional modelling of processes in Electron Cyclotron Resonance Ion Source

Three-dimensional modelling of processes in Electron Cyclotron Resonance Ion Source

Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma

Modeling space-resolved ion dynamics in ECR plasmas for predicting in-plasma β-decay rates

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