nascap-2k: simulating the interaction of spacecraft with the plasma environment david cooke adrian...
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Nascap-2K: Simulating the Interaction of Spacecraft with the
Plasma Environment
David CookeAdrian Wheelock
Air Force Research Laboratory, Hanscom AFB, Boston, MA
Myron J. Mandell, Victoria Davis,Jeffrey Hilton, Barbara Gardner
Science Applications International CorporationSan Diego, CA
Code: NASCAP/LEO (1980-1991)Applications: High Voltage Current Collection in Dense PlasmaSponsor: NASA
Code: NASCAP/LEO (1980-1991)Applications: High Voltage Current Collection in Dense PlasmaSponsor: NASA
Code: NASCAP/GEO (1976-1984)Applications: GEO S/C ChargingSponsors: NASA, Air Force
Code: NASCAP/GEO (1976-1984)Applications: GEO S/C ChargingSponsors: NASA, Air Force
Nascap-2K Replaces Earlier Spacecraft-Plasma Codes
Code: POLAR (1978-1991)Applications: Auroral Charging, WakesSponsor: Air Force
Code: POLAR (1978-1991)Applications: Auroral Charging, WakesSponsor: Air Force
Code: DynaPAC (1991-1999)Applications: Complex dense plasma phenomenaSponsor: AFRL
Code: DynaPAC (1991-1999)Applications: Complex dense plasma phenomenaSponsor: AFRL
Surfaces Accumulate Chargeto Achieve Current Balance
Physically, spacecraft surfaces arebombarded with charged particlesfrom the ambient plasma. Secondaryelectrons are emitted from spacecraftsurfaces.
Electrically, the net plasma currents chargespacecraft surface capacitances. Thecapacitances of the surfaces to thespacecraft chassis are much larger thanthose to the plasma.
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Why modeling spacecraft charging is difficultCurrents depend on potentials & fieldsTimescales vary by orders of magnitudeGeometrical details are importantDifferential charging barriers limit secondary electrons
Why modeling spacecraft charging is difficultCurrents depend on potentials & fieldsTimescales vary by orders of magnitudeGeometrical details are importantDifferential charging barriers limit secondary electrons
NASCAP2K Integrated Framework:Surface Potentials & Fields
Surfaces in 3-DObject Toolkit displaySurface Picking
ResultsSurface #Normal vectorPotentialEfieldCurrentConductor #
Surface Potentials after charging in NASA “Worst-Case” Environment
Tenuous Plasma Geosynchronous surface charging Solar Wind surface charging Potentials and Fields Particle Tracking
Dense Plasma External Potentials
•Analytic Space Charge•Hybrid Space Charge
Current Collection EP Plumes Auroral Charging PIC Maxwell’s Eq. (Darwin approx)
Nascap-2k Capabilities
Object Toolkit Examples
DMSP
SSULI
Users interactively size and edit standard shapes
Construct custom primitivesImport from common CAD programs
Examples of recent NASCAP2K Models
STEREO: Twin spacecraft to lead/lag Earth in solar orbit
Concern: Engineer for positive charging to aid electron detection instruments
MESSENGER: Space science mission to Mercury
Concern: Engineer for negative charging to aid ion detection instruments
Success Story: C/NOFSComm/Nav Outage Forecasting System
Ram-facing experiments and E-field probes require equipotential surfaces on ram facets.
SAIC and Spectrum-Astro used Nascap2K to show that an innovative surface grounding scheme could reduce ITO (conductive) coating thickness on solar cells saving ~1 M$ in custom processing.
Next Success Story: DSXDeployed Space Experiment
NASCAP2K models of DSX antenna-plasma interaction 3D electro-dynamic PIC simulation Dynamic sheath structure Ampere’s law magnetic perturbations Sheath dissipation or radiation? In-house parallel processing effort
Trajectory simulations to help place low energy ion and electron sensors
Points represent electron macroparticles.
Ion sheath conduction currents5 eV ion access with 5 kV sheath