A hybrid Boltzmann electrons and PIC ions model for simulating transient state of partially ionized plasma

Kwok, Dixon T. K.

doi:10.1016/j.jcp.2008.02.005

Cited by 7 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A dedicated scheme needs to be implemented in order to compute the reference density n 0 . While various schemes have been proposed which satisfy electrostatic or low frequency RF simulations [41,42], generalized RF simulations introduce a nontrivial displacement current which must also be conserved:…”

Section: Appendix a Charge Conservation Algorithm Augbisectionmentioning

confidence: 99%

Resonance in radio frequency sheath admittance and enhanced impurity emission near the ion cyclotron frequency

2023

View full text Add to dashboard Cite

Ion cyclotron resonance heating (ICRH) is of considerable interest among all auxiliary heating techniques, because it transfers power directly to ions, targets the high density core, and involves the cheapest radio-frequency (RF) components. During ICRH operation, RF sheaths form on the ICRH antenna itself, nearby hardware, and far-field surfaces. These sheaths are associated with large hot-spot formation and impurity emissions. This work presents high-resolution numerical modelling of RF sheaths in nuclear fusion scenarios using hPIC2, a Debye-scale particle-in-cell code. The modelling reveals a new RF sheath phenomenon which occurs when the radio frequency is resonant with a species ion cyclotron frequency or harmonic in an oblique magnetic field. This resonance of the RF sheath causes modifications of the energy-angle distributions of the ions impacting on the walls, with consequent increase in wall impurity emission. Due to the 1/R scaling of the magnetic field in a tokamak, such cases are possible on divertor or vacuum chamber surfaces, depending on the geometry of the tokamak and the RF heating scenario. A simple physics interpretation using a driven damped harmonic oscillator is proposed, where the ion sheath transit time plays the role of damping the RF sheath admittance. Critically, the resonance leads to increased ion heat flux at the wall as well as increased physical sputtering, despite a lack of increase in RF rectified sheath potential.

show abstract

Section: Appendix a Charge Conservation Algorithm Augbisectionmentioning

confidence: 99%

Resonance in radio frequency sheath admittance and enhanced impurity emission near the ion cyclotron frequency

2023

View full text Add to dashboard Cite

show abstract

“…The main idea that will be described in Section 2 is to use a nonlinear electrostatic formulation, where the Boltzmann relation is used to relate the local electron number density and electric potential. This allows to omit electrons from the drift diffusion equations, and to adopt grid spacing larger than the Debye length, with substantial beneficial effects in terms of computational efficiency [38,39]. Although this approach is well-established for hybrid fluid/particle-in-cell models used for low-pressure applications [40], e.g., for plasma thruster modeling [41,42], the authors of this work are not aware of applications of this technique to atmospheric pressure problems involving high voltages that change over time.…”

Section: Introductionmentioning

confidence: 99%

A Boltzmann Electron Drift Diffusion Model for Atmospheric Pressure Non-Thermal Plasma Simulations

Popoli,

Ragazzi,

Pierotti

et al. 2023

Plasma

View full text Add to dashboard Cite

We introduce a fluid computational model for the numerical simulation of atmospheric pressure dielectric barrier discharge plasmas. Ion and neutral species are treated with an explicit drift diffusion approach. The Boltzmann relation is used to compute the spatial distribution of electrons as a function of the electrostatic potential and the ionic charge density. This technique, widely used to speed up particle and fluid models for low-pressure conditions, poses several numerical challenges for high-pressure conditions and large electric field values typical of applications involving atmospheric-pressure plasmas. We develop a robust algorithm to solve the non-linear electrostatic Poisson problem arising from the Boltzmann electron approach under AC electric fields based on a charge-conserving iterative computation of the reference electric potential and electron density. We simulate a volumetric reactor in dry air, comparing the results yielded by the proposed method with those obtained when the drift diffusion approach is used for all charged species, including electrons. We show that the proposed methodology retains most of the physical information provided by the reference modeling approach while granting a substantial advantage in terms of computation time.

show abstract

“…Such hybrid strategies, treating ions in a fully kinetic manner and electrons via fluid approaches, are often used in today's simulations [4,6,12,22], leading to significant savings in computational time and memory. But, describing particles via a fluid model requires some assumptions, as for example to be close to a thermodynamic equilibrium, meaning to have a Maxwellian distribution in the velocity variable.…”

Section: Introductionmentioning

confidence: 99%

Fokker-planck Multi-species Equations In The Adiabatic Asymptotics

Filbet¹,

Negulescu²

2022

Preprint

View full text Add to dashboard Cite

The main concern of the present paper is the study of the multi-scale dynamics of thermonuclear fusion plasmas via a multi-species Fokker-Planck kinetic model. One of the goals is the generalization of the standard Fokker-Planck collision operator to a multispecies one, conserving mass, total momentum and energy, as well as satisfying Boltzmann's H-theorem. Secondly, the paper investigates in more details the reduced model used for the electron description in present simulations, and which considers the electrons in a thermodynamic equilibrium (adiabatic regime), whereas the ions are kept kinetic. On the one hand, we perform some mathematical asymptotic limits to obtain in the electron/ion low mass ratio limit the above-mentioned electron adiabatic regime. On the other hand, we develop a numerical scheme , based on a Hermite spectral method, and perfom numerical simulations to illustrate and investigate in more details this asymptotics.

show abstract

A hybrid Boltzmann electrons and PIC ions model for simulating transient state of partially ionized plasma

Cited by 7 publications

References 29 publications

Resonance in radio frequency sheath admittance and enhanced impurity emission near the ion cyclotron frequency

Resonance in radio frequency sheath admittance and enhanced impurity emission near the ion cyclotron frequency

A Boltzmann Electron Drift Diffusion Model for Atmospheric Pressure Non-Thermal Plasma Simulations

Fokker-planck Multi-species Equations In The Adiabatic Asymptotics

Contact Info

Product

Resources

About