Engineering Tool for Temperature, Electric Field and Dose Rate Dependence of Low Conductivity Spacecraft Materials

Dennison, JR; Sim, Alec; Brunson, Jerilyn; Gillespie, Jodie Corbridge; Hart, Steven; Dekany, Justin; Sim, Charles; Arnfield, Dan

doi:10.2514/6.2009-562

Cited by 10 publications

(5 citation statements)

References 24 publications

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“…The total conductivity ı Total of the dielectrics consists of thermally activated hopping steady-state conductivity (TAH) ı TAH , variable range hopping steady-state conductivity (VRH) ı VRH and radiation induced conductivity (RIC) ı RIC [6,7]. , , , , ,…”

Section: A Conductivity Modelmentioning

confidence: 99%

A simulation of deep dielectric charging induced by dielectric temperature and energetic electrons

Min

et al. 2010

2010 10th IEEE International Conference on Solid Dielectrics

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In this paper, a computer numerical simulation of onedimensional deep dielectric charging (DDC) of spacecrafts induced by temperature and energetic electrons has been developed. It provides a method for spacecraft engineers to analyze the phenomena of DDC in spacecrafts and then to predict whether or when electrostatic discharging (ESD) will occur. The simulation code is developed to analyze the influence of different magnitude of dielectric temperature and energetic electrons flux on deep dielectric charging/discharging occurrence. In the simulation, we find that there exists an ESD inception energetic electron flux threshold. The flux threshold decreases with the decrease of dielectric temperature. It is interesting that there exists a critical dielectric temperature (250 K for low-density polyethylene) in the DDC process. Below the critical temperature or above that, respectively, the energetic electron flux and the dielectric temperature are the dominated influencing factors in the DDC process. Then, considering the DDC electric field and the charging time, we present a rough prediction of discharging occurrence probability with varied flux of energetic electrons and dielectric temperature.

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Section: A Conductivity Modelmentioning

confidence: 99%

A simulation of deep dielectric charging induced by dielectric temperature and energetic electrons

Min

et al. 2010

2010 10th IEEE International Conference on Solid Dielectrics

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“…Dissipation or redistribution of this accumulated charge throughout a spacecraft is governed primarily by the conductivity of high resistivity components of the spacecraft. 3,12,27 In turn, conductivity is substantially affected by the charge and energy deposited by the incident radiation fluxes, which modify the electric field stress, temperature, and absorbed radiation energy dose of the material.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…Kapton are well understood. 27,28,29 For example, previous studies have measured materials properties and determined appropriate parameters for NASCAP fits for materials such as graphite (used in the base of the spacecraft cone and struts) and black Kapton (spacecraft bus). 30 When these data are unavailable, as was the case here for the proposed ceramic Solar Probe coatings, it must be measured in order to appropriately model charging effects.…”

Section: Materials Propertiesmentioning

confidence: 99%

“…The observed temperature dependence of k RIC and Δ is consistent with predictions based on the Rose-Fowler multiple trapping model. 27,58,59 63 It is important to recognize that RIC will only produce enhanced charge transport within the upper layer of a dielectric coating to a depth R (see discussion below), and will lead to charge dissipation only if this surface layer has a conduction path to areas of differential charge or a local ground; it will not significantly enhance the charge dissipation through the Solar Probe ceramic coating-with a thickness ~10 3 π π (7) The range 8,39 for Al 2 O 3 at incident energies from 10 4 eV to 10 6 eV in the continuous slow down approximation is tabulated in the ESTAR database. 51 The ranges for PBN and BaZP in this energy interval are approximated by scaling the Al 2 O 3 range data by the ratio of Al 2 O 3 density to the PBN or BaZP density using the ESTAR database.…”

Section: Electrostatic and Related Materials Propertiesmentioning

confidence: 99%

See 1 more Smart Citation

Spacecraft Coating-Induced Charging: Materials and Modeling Study of Environmental Extremes

Donegan¹,

Sample²,

Dennison³

et al. 2010

Journal of Spacecraft and Rockets

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As mankind reaches to explore extreme environments in space, the application of ceramics surface coatings is increasing. The 2005 mission concept for Solar Probe used a unique design to achieve the necessary thermal control for a very close approach to the solar corona, including the use of a highly refractory, electrically insulating ceramic coating over a carbon-carbon composite heat shield. The proposed trajectory takes the spacecraft from a Jovian fly-by to within 4 solar radii of the Sun, spanning 5 orders of magnitude in solar radiation and solar wind plasma density as well as spacecraft temperatures from <100 K to >2000 K. Using the NASCAP-2K charging modeling program, the degree of charging expected for this spacecraft design has been calculated for this range of radiation environments. New measurements of the electron emission and estimates of related properties of the candidate materials-Al 2 O 3 , pyrolytic born nitride and barium zirconium phosphate-are presented. Absolute and differential surface charging are found to depend strongly on temperature through increased conductivity at higher temperatures and on radiation flux through enhanced charge accumulation and radiation induced conductivity. As the spacecraft approaches the Sun, the competition between increased charge dissipation at higher temperatures and increased charge accumulation at higher fluxes leads to a maximum in differential charging between 0.4 AU and 2 AU. While the spacecraft charging behavior of these materials is found to be significant, it is not severe enough to endanger the mission, and a number of options exist to mitigate the degree of charging. Among the ceramics considered, the use of Al 2 O 3 coatings is found to minimize both absolute and differential spacecraft charging. [Type text] 2 E max = energy at maximum secondary emission δ max occurs el inc E = incident electron energy BSE emit J = emitted current due to backscattered electron emission ion emit J , photo emit J = emitted current due to ion-induced and photon-induced secondary electron emission SE emit J = emitted current due to electron-induced secondary electron emission el inc J , ions inc J = incident electron and ion currents el inc J is the incident electron current, ions inc J is the incident ion current, SE emit J is the current out due to electroninduced secondary electron emission, BSE emit J is the current out due to backscattered electron emission, ion emit J is the current out due to ion-induced secondary electron emission, and photo emit el inc net J J J J J J J + + + − + =(1) Note that in our convention electron currents are negative due to the sign of the charge carrier.At equilibrium, J net = 0, such that the current into the spacecraft (in the form of incident ions and electrons) equals the current out of the spacecraft (due to photoemission, secondary electron emission, and backscattered electrons) such that a potential develops relative to the surrounding plasma "ground." Absolute charging develops when the local "ground" of the entire spacecr...

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“…Considering three conductivity mechanisms of radiation induced conductivity (RIC), thermal assisted hopping conductivity (TAR) and variable range hopping conductivity (VRH) [ 9 ] , space charge density at time t can be obtained by current continuity equation [ lO ] ' raJ (x,t)…”

Section: Introductionmentioning

confidence: 99%

Internal charging in low density polyethylene irradiated by energetic electrons

Zhao

Min

et al. 2012

2012 IEEE 10th International Conference on the Properties and Applications of Dielectric Materials

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Basing on the range theory of European Space Agency (ESA) and Touzin's charge deposition theories, a 1-0 internal charging model has been employed in simulating the effects of incident electron flux (IEF) and irradiation time on deep dielectric charging (DOC). It is calculated that the distribution of electric field, conductivity and space charge under both different IEF and time. The results indicate there is an IEF threshold, about 2.0 x 1012 /m:s., on which conductivity mechanism changes and the development velocity of electric field distortion decreases. Moreover, thermal assisted hopping conductivity (TAH) is the vital influence factor of the internal charging/discharging.The results are useful for understanding the mechanism of charge transport and internal charging/discharging phenomenon.

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Engineering Tool for Temperature, Electric Field and Dose Rate Dependence of Low Conductivity Spacecraft Materials

Cited by 10 publications

References 24 publications

A simulation of deep dielectric charging induced by dielectric temperature and energetic electrons

A simulation of deep dielectric charging induced by dielectric temperature and energetic electrons

Spacecraft Coating-Induced Charging: Materials and Modeling Study of Environmental Extremes

Internal charging in low density polyethylene irradiated by energetic electrons

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