Particle-in-cell simulations of anomalous transport in a Penning discharge

Carlsson, Johan; Kaganovich, Igor; Powis, Andrew; Raitses, Yevgeny; Romadanov, Ivan; Smolyakov, Andrei

doi:10.1063/1.5017467

Cited by 33 publications

(25 citation statements)

References 27 publications

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“…The cross field anomalous E ×B electron transport due to the large-scale spoke perturbations was measured insitu and, for the dielectric, seen to account for a 40−100% of the total discharge current, resulting in a β D eff ≈ 10 consistent with computational work 33,36 . Transport becomes more spread and closer to levels of classical collisional transport with the metal as boundary (β M eff ≈ 10β D eff ).…”

Section: Discussionsupporting

confidence: 63%

“…This non-dimensional parameter is approximatedly β D eff ≈ 8(6) for B = 30 G in Case I at the edge r = 8 cm, consistent with values presented in some numerical PIC simulations of Penning discharges. 33,36 When the metallic flange is placed, the total cross field transport in the plasma drops very significantly (see Fig. FIG.…”

Section: Changes In Anomalous E × B Electron Cross-field Currentmentioning

confidence: 99%

“…Alongside these theoretical efforts, computational modelling has become increasingly important in extending present understanding of the spoke. Amongst the many numerical approaches available [31][32][33][34] , simulations employing Particle-in-cell (PIC) codes 33,35 have lately gained relevance, including simulations of real sized devices 36 . Indeed, 'spoke-like' structures have been shown to appear in such recreated devices even in the simplest formulations, such as in the abscence of ionisation or collisions.…”

Section: Introductionmentioning

confidence: 99%

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Boundary-induced effect on the spoke-like activity in E × B plasma

et al. 2019

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The spoke instability in an E × B Penning discharge is shown to be strongly affected by the boundary that is perpendicular to B field lines. The instability is the strongest when bounded by dielectric walls. With a conducting wall, biased to collect electron current from the plasma, the spoke becomes faster, less coherent and localised closer to the axis. The corresponding anomalous cross-field transport is assessed via simultaneous time-resolved measurements of plasma potential and density. This shows a dominant large-scale E×B anomalous character of the electron cross-field current for dielectric walls reaching 40-100% of the discharge current, with an effective Hall parameter β eff ∼ 10. The anomalous current is greatly reduced with the conducting boundary (characterised by β eff ∼ 10 2 ). These experimental measurements are shown to be qualitatively consistent with the decrease of the E field that triggers the collisionless Simon-Hoh instability.

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Section: Discussionsupporting

confidence: 63%

Section: Changes In Anomalous E × B Electron Cross-field Currentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Boundary-induced effect on the spoke-like activity in E × B plasma

et al. 2019

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“…Instabilities in a large range of frequency and wavelength, from large scale "rotating spokes" to submillimeter structures have been reported experimentally or by simulations in the partially magnetized plasmas of Hall thrusters 7,8,[11][12][13][14][15][16][17][18][19][20][21][22][23][24] , magnetrons 8,[25][26][27][28][29] , ion sources for neutral beam injection 30 , cylindrical magnetized plasma column [31][32][33][34][35][36] and Penning ion sources [37][38][39] . These instabilities are very dependent on the specific conditions or regions of a particular device.…”

Section: Introductionmentioning

confidence: 99%

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Boeuf

2019

Physics of Plasmas

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Electron and ion transport in the near-anode region of a partially magnetized plasma under conditions typical of Hall thrusters or magnetron discharges is studied with fully kinetic, Particle-In-Cell Monte Carlo Collision (PIC-MCC) simulations assuming a uniform magnetic field and no ionization. We derive a simple relation that defines the magnetic field at the transition point between negative and positive sheath. For magnetic fields around or above this transition point, PIC-MCC simulations show the development of short wavelength azimuthal instabilities that cascade to longer wavelengths ("rotating spokes") as the magnetic field is increased. Both short-wavelength and large-wavelength fluctuations can coexist under some conditions. A detailed study of the fluid dispersion relation is used to analyze the PIC-MCC results. Small coherent structures can be associated with the destabilization of ion sound waves by density gradient and collisions. Longer wavelengths or rotating spokes are characteristic of the collisionless Simon-Hoh instability. The small structures are dominant for larger plasma density gradients while the larger structures correspond to smaller density gradients and larger magnetic fields. Anomalous transport associated with these instabilities can be significant, with effective collision frequencies larger than 2 × 10 7 s −1 in xenon for magnetic fields above the transition point.

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“…Fluctuating azimuthal electric fields can induce a radial E × B drift-diffusion of the electrons, which is called anomalous diffusion, and reduces the electron storage time in the trap [12][13][14][15]. There are various plasma instabilities; one example, which could be interesting for our Penning trap, is the cross-field (E × B) instability which requires a radial plasma density gradient and an inwardly directed radial electric field in the trap [16,17]. (c) The ions, created along with the secondary electrons, are not trapped inside the inter-spectrometer Penning trap and can leave toward the spectrometers.…”

Section: Inter-spectrometer Penning Trap Problem and Countermeasuresmentioning

confidence: 99%

Suppression of Penning discharges between the KATRIN spectrometers

et al. 2020

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The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)neutrino mass with a sensitivity of 0.2eV/c 2 by precisely measuring the endpoint region of the tritium β-decay spectrum. It uses a tandem of electrostatic spectrometers working as magnetic adiabatic collimation combined with an electrostatic (MAC-E) filters. In the space between the prespectrometer and the main spectrometer, creating a Penning trap is unavoidable when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create additional background electrons and endanger the spectrometer and detector section downstream. To counteract this problem, "electron catchers" were installed in the beamline inside the magnet bore between the two spectrometers. These catchers can be moved across the magnetic-flux tube and intercept on a sub-ms time scale the stored electrons along their magnetron motion paths. In this paper, we report on the design and the successful commissioning of the electron catchers and present results on their efficiency in reducing the experimental background.

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Particle-in-cell simulations of anomalous transport in a Penning discharge

Cited by 33 publications

References 27 publications

Boundary-induced effect on the spoke-like activity in E × B plasma

Boundary-induced effect on the spoke-like activity in E × B plasma

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Suppression of Penning discharges between the KATRIN spectrometers

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