Kinetic Modeling of the Sheath Scale in the Lunar Plasma Environment
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Transcript of Kinetic Modeling of the Sheath Scale in the Lunar Plasma Environment
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Kinetic Modeling of the Sheath Scale in the Lunar Plasma
Environment
Tech-X Corporation5621 Arapahoe Ave., Boulder, CO 80303
http://www.txcorp.com
Peter Messmer*, Keegan Amyx, Peter Stoltz, Andrew Poppe, Mihay Horanyi, Scott
Robertson, Zoltan Sternovsky [email protected]
CCLDAS All Hands Meeting, Boulder, CO, July 10, 2009
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VORPAL -A Plasma Modeling Framework
Original target applications: Laser Wakefield Acceleration
PIC, Fluid, HybirdElectrostatic, EMMulti-Dimensional (N=1,2,3)Fully parallel
Scaling for > 32,000 PEs Flexible domain decomposition
Broad range of physics features:- Complex geometries- Ionization, recombination, CEX physics- Field ionization
http://www.txcorp.com/products/VORPAL
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Code/setup Validation with 1D Photoelectron Sheath
R. Garad & J Tunaley, JGR 76(10), 2498, 1971
A. Poppe & M. Horanyi, WPDP, 2009
2D ES simulation, Y periodic ,200 x 10 cellsdx = 1050 particles per cell nominal
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Simulation
Garad&Tunaley
Monoenergetic
Maxwellian
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2D Monoenergetic Sheath
2D ES simulation, left wall = 0V200 x 100 cellsElectrons, ProtonsMonoenergetic ,V0 = 200 eV (!)
electrons
protons
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Scenario with Surface Charging
Surface-Charging No surface charging
(just for comparison)
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2D Thermal Sheath with Surface Charging
2D ES simulation, left wall = 0V200 x 100 cellsElectronsHeavy Protons, Heavy electrons (m/m0= 5000)Vsig = 3eV, Vtherm = 3 eV
Electron impact creates“heavy electrons”
Electrons get absorbed
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Electric field mainly due to positive charge of emitting
region
ChargingNon Charging
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“Heavy Electrons” follow the electric field lines
2D ES simulation, left wall = 0V200 x 100 cellsElectronsHeavy Protons, Heavy electrons (m/m0= 5000)Vsig = 3eV, Vtherm = 3 eV
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Initial 3D simulations
3D ES simulation, bottom wall = 0V10 x 100 x 100 cellsElectronsProtons, Heavy electrons (m/m0= 5000)Vsig = 3eV, Vtherm = 3 eV
Charging of surface
No charging of surface
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Summary / Conclusions / Future work
Presented VORPAL simulations of plasma sheath Validated with kinetic theory for 1D sheath Presented 2D simulation with/without surface charging “heavy electrons” move in electrostatic field, follow (curved)
field lines
Future work: Convergence studies, more realistic parameters Inclusion of solar wind Time dependent problems, angular dependency of photo-
currents Complex geometries (crater, habitat, instrument) 3D
Work supported by CCLDAS and Tech-X Corp.