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Harris sheet solution for magnetized quantum plasmas Fernando Haas ferhaas@unisinos.br Unisinos, Brazil
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Quantum plasmas High density systems (e.g. white dwarfs) Small scale systems (e.g. ultra- small electronic devices) Low temperatures (e.g. ultra-cold dusty plasmas)
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Some developments Dawson’s (multistream) model applied to quantum two-stream instabilities [Haas, Manfredi and Feix, PRE 62, 2763 (2000)] Quantum MHD equations [Haas, PoP 12, 062117 (2005)] Quantum modulational instabilities (modified Zakharov system) [Garcia, Haas, Oliveira and Goedert, PoP 12, 012302 (2005)] Quantum ion-acoustic waves [Haas, Garcia, Oliveira and Goedert, PoP 10, 3858 (2003)]
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Modeling quantum plasmas Microscopic models: N-body wave-function density operator Wigner function Macroscopic models: hydrodynamic formulation
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Wigner-Poisson system
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Remarks In the formal classical limit ( ) the Wigner equation goes to the Vlasov equation The Wigner function can attain negative values (a pseudo-probability distribution only) The Wigner function can be used to compute all macroscopic quantities (density, current, energy and so on)
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Hydrodynamic variables
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Quantum hydrodynamic model (electrostatic plasma)
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Bohm’s potential or quantum pressure term:
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Application: quantum two-stream instability [Haas et al., PRE (2000)]
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The quantum parameter (two-stream instability)
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Magnetized quantum plasmas Electromagnetic Wigner equation: [Haas, PoP (2005)] This is an ugly looking equation so I will not try to show it! Sensible simplifications are needed hydrodynamic models
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Quantum hydrodynamics for (non- relativistic) magnetized plasma plus Maxwell’s equations and an equation of state.
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Quantum magnetohydrodynamics Highly conducting two-fluid plasma merging QMHD [Haas, PoP (2005)] The quantum parameter (QMHD):
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One-component magnetized quantum plasma: “1D” equilibrium
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Vector potential
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A pseudo-potential
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Ampere's law equivalent to a Hamiltonian system
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Pressure balance equation It can be shown that
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Remarks In general, the balance equation is an ODE for the density n Solving the Hamiltonian system for yields simultaneously and
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Rewriting the balance equation
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Free ingredients The pressure p = p(n) The pseudo-potential
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Harris sheet solution In classical plasmas, the Harris solution more frequently is build using the energy invariant to solves Vlasov In quantum plasmas, in general a function of the energy is not a solution for Wigner This also poses difficulties for quantum BGK modes
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Choice for Harris sheet magnetic field
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Solving for and then for (using suitable BCs)
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Balance equation for quantum Harris sheet solution Using a suitable rescaling:
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Quantum parameter (quantum Harris sheet) It increases with 1/m, 1/L, and the ambient density.
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Classical limit
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Ultra-quantum limit
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Numerical simulations (H=3) -15-10-5510 15 0.2 0.4 0.6 0.8 1 1.2
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Numerical simulations (H=5)
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Final remarks In the quantum case, a Harris-type magnetic field (together with ) is associated to an oscillating density The velocity field is also modified (it depends on the density) Stability questions were not addressed - what is the role of quantum correlations?
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