Spacecraft charging calculations - Nascap-2K and SEE Spacecraft Charging Handbook

Davis, V. A.; Neergaard, Linda F.; Mandell, M. J.; Katz, Ira; Gardner, B.; Hilton, J.; Minor, Jody

doi:10.2514/6.2002-626

Cited by 6 publications

(6 citation statements)

References 4 publications

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“…The results of model simulations of spacecraft charging are presented in [24,25] and other papers, while estimations by analytical and numerical methods are made in [7] and in the present paper.…”

Section: Calculation Of Electrostatic Fields Near Low-orbit Spacecraftmentioning

confidence: 99%

“…American programs include NASCAP/GEO (developed specially for geosynchronous orbits), NASCAP/LEO (considers interactions of rarefied plasma having a small Debye length λ D with high-voltage constructions of spacecraft), and POLAR (specially written for the auroral ionosphere). Modern means of computer technology, software, design, and mathematical analysis methods allowed these programs to be joined into single software package Nascap-2K [24].…”

Section: Calculation Of Electrostatic Fields Near Low-orbit Spacecraftmentioning

confidence: 99%

“…Point A corresponds to the value of the field strength on the irradiated surface at potential U d , point D is the field strength value near the substrate at potential U c , and point F corresponds to potential U Σ (see expression (26)). When system of equations (20)-(23) is solved numerically with boundary conditions (24), (25), the value of E(x) is determined by curve ABCF. The absolute error of calculation is found from a comparison of the areas hatched in the figure, limited by line AD and integrated function E(x) (i.e., ABC and CDF).…”

Section: Calculation Of Electrophysical Characteristics Of Spacecraftmentioning

confidence: 99%

“…At first, the density of conduction current on the irradiated surface was determined (24) where j e and j 1 are the current densities of primary electrons and ions, respectively; U d is the potential of the open surface of the spacecraft's dielectric coating; γ(E i ) is the coefficient of ion-electron emission depending on the ion energy E i [3]; and δ(E e ) is the coefficient of true secondary electron-electron emission which depends 7 It is assumed that the exchange take place between the energy levels (traps) located above the Fermi level E F . Only the capture of carriers without their subsequent release proceeds onto the levels below E F .…”

Section: Calculation Of Electrophysical Characteristics Of Spacecraftmentioning

confidence: 99%

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Electric Polarization of Low-Orbit Spacecraft

Skriabysheva

2005

Cosmic Res

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Section: Calculation Of Electrostatic Fields Near Low-orbit Spacecraftmentioning

confidence: 99%

Section: Calculation Of Electrostatic Fields Near Low-orbit Spacecraftmentioning

confidence: 99%

Section: Calculation Of Electrophysical Characteristics Of Spacecraftmentioning

confidence: 99%

Section: Calculation Of Electrophysical Characteristics Of Spacecraftmentioning

confidence: 99%

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Electric Polarization of Low-Orbit Spacecraft

Skriabysheva

2005

Cosmic Res

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“…Along the Z axis the velocity increment is calculated as if the temperature were T -2mu2 1+ m2 -1j. 8. The new particles have the same properties as the original particle except for velocity, weight (charge), and temperature.…”

Section: " Mu2mentioning

confidence: 99%

NASCAP-2K Spacecraft-Plasma Environment Interactions Modeling: New Capabilities and Verification

Davis

Mandell

Cooke

et al. 2007

45th AIAA Aerospace Sciences Meeting and Exhibit

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. ABSTRACTNascap-2k is a three-dimensional computer code that models interactions between spacecraft and plasma environments in low-Earth, auroral, geosynchronous, and interplanetary orbits. Previously, we reported on the accuracy of Nascap-2k's charging and current collections calculations by comparing computed currents and potentials with analytic results, and by comparing Nascap-2k results with published calculations using the earlier lower resolution codes, NASCAP/GEO, NASCAP/LEO, and POLAR. Here we examine the accuracy and limitations of two new capabilities of Nascap-2k: modeling of plasma plumes such as generated by electric thrusters and enhanced PIC computational capabilities. Nascap-2k models one or more ion engine plumes in full three-dimensional geometry, including plume-plume plume-spacecraft interactions. The primary thruster beam, parameters describing the neutral efflux, and the initial charge-exchange plume are imported from a PlumeTool generated file. Nascap-2k generates and tracks charge-exchange ions to obtain plasma densities and calculates potentials consistent with plasma densities and object surfaces. Nascap-2k's PIC capability has been expanded to include boundary injection, particle splitting, and substep charge deposition. We use calculations for simple geometries to explore the accuracy and limitations of these capabilities. Nascap-2k is a three-dimensional computer code that models interactions between spacecraft and plasma environments in low-Earth, geosynchronous, auroral, and interplanetary orbits. The code builds on physical principles, mathematical algorithms, and user experience developed over three decades of spacecraft charging research. Nascap-2k has improved numeric techniques, a modern user interface, and a simple, interactive satellite surface definition module (Object ToolKit). SUBJECT TERMSCapabilities Include surface charging in geosynchronous and interplanetary orbits, sheath and wake structure and current collection in low-Earth orbits, and auroral charging. External potential structure and particle trajectories are computed using a finite element method on a nested grid structure and may be visualized within the Nascap-2k interface. Space charge can be treated either analytically, self-consistently with particle trajectories, or consistent with imported plume densities. Particle-in-cell (PIC) capabilities are available to study dynamic plasma effects.Previously, we reported on the accuracy of Nascap-2k's charging and current collection calculations by comparing computed currents and potentials with analytic results, and by comparing Nascap-2k results with published calculations using the earlier lower resolution codes, NASCAP/GEO, NASCAP/LEO, and POLAR. Here we examine the accuracy...

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Representation of the measured geosynchronous plasma environment in spacecraft charging calculations

2008

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1] Historically, the characterization of the magnetospheric environment has limited our ability to determine spacecraft surface charging levels. One difficulty lies in the common practice of fitting the plasma data to a Maxwellian or Double Maxwellian distribution function, which may not represent the data well for use in spacecraft charging simulations. We use electron and ion flux spectra measured by the Los Alamos National Laboratory (LANL) Magnetospheric Plasma Analyzer (MPA) during eclipse in September 2001 to examine how the use of different spectral representations of the charged particle environment in computations of spacecraft potentials during magnetospheric substorms affects the accuracy of the results. We examine charging and noncharging flux spectra and the relationships between the density and temperature moments. We then calculate the spacecraft potential (zero net current) using both the measured fluxes and several different fits to these fluxes. The potential computed using the measured fluxes and secondary and backscattered fluxes computed for graphite carbon, with a constant fraction of 81% of secondary electrons escaping, is within a factor of three of the measured potential for 87% of the data. Potentials calculated using a Kappa function fit to the electron flux and a Maxwellian function fit to the ion flux agree with measured potentials nearly as well. Alternative spectral representations give less accurate estimates. The use of all the components of the net flux, along with spacecraft specific average material properties, gives a better estimate of the spacecraft potential than the measured flux from a single high-energy channel.Citation: Davis, V. A., M.

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Spacecraft charging calculations - Nascap-2K and SEE Spacecraft Charging Handbook

Abstract: ABSTRACT

Cited by 6 publications

References 4 publications

Electric Polarization of Low-Orbit Spacecraft

Electric Polarization of Low-Orbit Spacecraft

NASCAP-2K Spacecraft-Plasma Environment Interactions Modeling: New Capabilities and Verification

Representation of the measured geosynchronous plasma environment in spacecraft charging calculations

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