Collisional effects on the numerical recurrence in Vlasov-Poisson simulations

Journal Article · Mon Feb 15 04:00:00 EST 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4940963· OSTI ID:22493878

Pezzi, Oreste; Valentini, Francesco ^[1]; Camporeale, Enrico ^[2]

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1. Dipartimento di Fisica and CNISM, Università della Calabria, 87036 Rende (CS) (Italy)
2. Center for Mathematics and Computer Science (CWI), 1090 GB Amsterdam (Netherlands)

The initial state recurrence in numerical simulations of the Vlasov-Poisson system is a well-known phenomenon. Here, we study the effect on recurrence of artificial collisions modeled through the Lenard-Bernstein operator [A. Lenard and I. B. Bernstein, Phys. Rev. 112, 1456–1459 (1958)]. By decomposing the linear Vlasov-Poisson system in the Fourier-Hermite space, the recurrence problem is investigated in the linear regime of the damping of a Langmuir wave and of the onset of the bump-on-tail instability. The analysis is then confirmed and extended to the nonlinear regime through an Eulerian collisional Vlasov-Poisson code. It is found that, despite being routinely used, an artificial collisionality is not a viable way of preventing recurrence in numerical simulations without compromising the kinetic nature of the solution. Moreover, it is shown how numerical effects associated to the generation of fine velocity scales can modify the physical features of the system evolution even in nonlinear regime. This means that filamentation-like phenomena, usually associated with low amplitude fluctuations contexts, can play a role even in nonlinear regime.

• OSTI ID: 22493878
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 2 Vol. 23; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AMPLITUDES
COLLISIONS
COMPUTERIZED SIMULATION
DAMPING
FLUCTUATIONS
LANGMUIR FREQUENCY
MATHEMATICAL SOLUTIONS
MATHEMATICAL SPACE
NONLINEAR PROBLEMS
PLASMA INSTABILITY