scholarly journals Implementation and verification of a conservative, multi‐species , gyro‐averaged , full‐ f , Lenard‐Bernstein /Dougherty collision operator in the gyrokinetic code GENE‐X

2021 ◽  
Author(s):  
Philipp Ulbl ◽  
Dominik Michels ◽  
Frank Jenko
Keyword(s):  
Collision Operator ◽  
Code Gene

scholarly journals Benchmark of a new multi-ion-species collision operator for δf Monte Carlo neoclassical simulation

2020 ◽  
Vol 255 ◽  
pp. 107249 ◽  
Author(s):  
Shinsuke Satake ◽  
Motoki Nataka ◽  
Theerasarn Pianpanit ◽  
Hideo Sugama ◽  
Masanori Nunami ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Collision Operator ◽  
Ion Species

Diffusion limit of a Boltzmann–Poisson system with nonlinear equilibrium state

2019 ◽  
Vol 16 (01) ◽  
pp. 131-156
Author(s):  
Lanoir Addala ◽  
Mohamed Lazhar Tayeb
Keyword(s):  
Nonlinear Diffusion ◽  
Collision Operator ◽  
Nonlinear Diffusion Equation ◽  
One Dimension ◽  
Diffusion Limit ◽  
Poisson System ◽  
Nonlinear Relaxation ◽  
Contraction Property ◽  
Hilbert Expansion ◽  
Nonlinear Equilibrium

The diffusion approximation for a Boltzmann–Poisson system is studied. Nonlinear relaxation type collision operator is considered. A relative entropy is used to prove useful [Formula: see text]-estimates for the weak solutions of the scaled Boltzmann equation (coupled to Poisson) and to prove the convergence of the solution toward the solution of a nonlinear diffusion equation coupled to Poisson. In one dimension, a hybrid Hilbert expansion and the contraction property of the operator allow to exhibit a convergence rate.

scholarly journals Shock Structure and Relaxation in the Multi-Component Mixture of Euler Fluids

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 955
Author(s):  
Damir Madjarević ◽  
Milana Pavić-Čolić ◽  
Srboljub Simić
Keyword(s):  
Relaxation Times ◽  
Thermal Relaxation ◽  
Collision Operator ◽  
Weak Form ◽  
Shock Structure ◽  
Theory Approach ◽  
Component Mixture ◽  
Single Temperature ◽  
The Difference ◽  
Euler Fluids

The shock structure problem is studied for a multi-component mixture of Euler fluids described by the hyperbolic system of balance laws. The model is developed in the framework of extended thermodynamics. Thanks to the equivalence with the kinetic theory approach, phenomenological coefficients are computed from the linearized weak form of the collision operator. Shock structure is analyzed for a three-component mixture of polyatomic gases, and for various combinations of parameters of the model (Mach number, equilibrium concentrations and molecular mass ratios). The analysis revealed that three-component mixtures possess distinguishing features different from the binary ones, and that certain behavior may be attributed to polyatomic structure of the constituents. The multi-temperature model is compared with a single-temperature one, and the difference between the mean temperatures of the mixture are computed. Mechanical and thermal relaxation times are computed along the shock profiles, and revealed that the thermal ones are smaller in the case discussed in this study.

Moments of the Boltzmann collision operator for Coulomb interactions

2021 ◽  
Vol 28 (7) ◽  
pp. 072113
Author(s):  
Jeong-Young Ji ◽  
Min Uk Lee ◽  
Eric D. Held ◽  
Gunsu S. Yun
Keyword(s):  
Collision Operator ◽  
Coulomb Interactions ◽  
Boltzmann Collision Operator

Anomalous transport coefficients in a magnetized turbulent plasma

1982 ◽  
Vol 28 (2) ◽  
pp. 193-214 ◽  
Author(s):  
Qiu Xiaoming ◽  
R. Balescu
Keyword(s):  
Transport Coefficients ◽  
Collision Operator ◽  
Turbulent Plasma ◽  
Anomalous Transport ◽  
Weak Turbulence ◽  
Dissipative Effects ◽  
Dependent Transport ◽  
Two Fluid ◽  
Two Fluid Plasma

In this paper we generalize the formalism developed by Balescu and Paiva-Veretennicoff, valid for any kind of weak turbulence, for the determination of all the transport coefficients of an unmagnetized turbulent plasma, to the case of a magnetized one, and suggest a technique to avoid finding the inverse of the turbulent collision operator. The implicit plasmadynamical equations of a two-fluid plasma are presented by means of plasmadynamical variables. The anomalous transport coefficients appear in their natural places in these equations. It is shown that the necessary number of transport coefficients for describing macroscopically the magnetized turbulent plasma does not exceed the number for the unmagnetized one. The typical turbulent and gyromotion terms, representing dissipative effects peculiar to the magnetized system, which contribute to the frequency-dependent transport coefficients are clearly exhibited.

Unitary quantum lattice gas algorithm generated from the Dirac collision operator for 1D soliton–soliton collisions

2015 ◽  
Vol 170 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Armen Oganesov ◽  
George Vahala ◽  
Linda Vahala ◽  
Jeffrey Yepez ◽  
Min Soe ◽  
...  
Keyword(s):  
Lattice Gas ◽  
Collision Operator ◽  
Quantum Lattice ◽  
Quantum Lattice Gas ◽  
Soliton Collisions

Two temperature gas equilibration model with a Fokker-Planck type collision operator

2014 ◽  
Author(s):  
A. R. Méndez ◽  
G. Chacón-Acosta ◽  
A. L. García-Perciante
Keyword(s):  
Collision Operator ◽  
Two Temperature ◽  
Equilibration Model ◽  
Fokker Planck

scholarly journals Generalized collision operator for fast electrons interacting with partially ionized impurities

2018 ◽  
Vol 84 (6) ◽  
Author(s):  
L. Hesslow ◽  
O. Embréus ◽  
M. Hoppe ◽  
T. C. DuBois ◽  
G. Papp ◽  
...  
Keyword(s):  
Growth Rate ◽  
Electric Fields ◽  
Collision Operator ◽  
Impurity Content ◽  
Fast Electrons ◽  
Generalized Operator ◽  
Partially Ionized ◽  
High Electric Fields ◽  
Bound Electrons ◽  
Fokker Planck

Accurate modelling of the interaction between fast electrons and partially ionized atoms is important for evaluating tokamak disruption mitigation schemes based on material injection. This requires accounting for the effect of screening of the impurity nuclei by the cloud of bound electrons. In this paper, we generalize the Fokker–Planck operator in a fully ionized plasma by accounting for the effect of screening. We detail the derivation of this generalized operator, and calculate the effective ion length scales, needed in the components of the collision operator, for a number of ion species commonly appearing in fusion experiments. We show that for high electric fields, the secondary runaway growth rate can be substantially larger than in a fully ionized plasma with the same effective charge, although the growth rate is significantly reduced at near-critical electric fields. Furthermore, by comparison with the Boltzmann collision operator, we show that the Fokker–Planck formalism is accurate even for large impurity content.

Sign in / Sign up

Export Citation Format

Share Document