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Temperature Dependence of Electrostatic Breakdown of Polymeric Insulators Utah State University DigitalCommons@USU Presentations Materials Physics Fall 10-23-2009 Temperature Dependence of Electrostatic Breakdown of Polymeric Insulators Charles Sim Utah State University JR Dennison Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/mp_presentations Part of the Physics Commons Recommended Citation Sim, Charles and Dennison, JR, "Temperature Dependence of Electrostatic Breakdown of Polymeric Insulators" (2009). American Physical Society Four Corner Section Meeting. Presentations. Paper 76. https://digitalcommons.usu.edu/mp_presentations/76 This Presentation is brought to you for free and open access by the Materials Physics at DigitalCommons@USU. It has been accepted for inclusion in Presentations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Temperature Dependence of Electrostatic Breakdown of Polymeric Insulators USU Materials Physics Group Charles Sim and JR Dennison Utah State University, Logan, Utah 84322-4415 Phone: (859) 559-3302, FAX: (435) 797-2492, E-mail: [email protected] Abstract Results Experimental Methods The temperature dependence of electrostatic discharge (ESD) of polymeric Measurements of the temperature dependence of ESD show significant damage to samples at breakdown. Polymer samples are placed inside the chamber (Fig. 9) and clamped between a metal sample insulators has been measured by applying a high voltage across the polymer to mounting plate and a Cu high voltage electrode (Fig. 12). Voltage is applied to a copper induce an electrical breakdown. The breakdown electric field was determined by electrode, increased at a rate of 20 volts every 4 seconds. Current and voltage are monitored a rapid rise in the I-V curves that were measured in a custom, high vacuum using two interfaced multimeters under LabVIEW control (Fig. 14). Electrostatic breakdown chamber in the temperature range of 150 K to 300 K. Our results showed that the occurs when the electric field exceeds the dielectric strength of the polymer (Fig. 11). electrostatic discharge of the polymer Low Density Polyethylene (LDPE) to be Current increases significantly at breakdown and continues to rise linearly above breakdown 318±60 (±18%) MV/m with no significant variation over the full temperature range. with a slope set by Ohm’s Law and two current limiting resistors. The results are compared with thermodynamic models of the electric field range aging process and limited prior measurements. The motivation for this research was the concern of spacecraft charging and the potential damage from electrostatic breakdown of polymers to be used on the James Webb Space 20 µm 20 µm 10 mm Telescope, which will operate at temperatures down to 30 K. Figure 4. Images of breakdowns. Kapton E usually breaks down with circular holes (left), while LDPE is more irregular (center). ePTFE can breakdown rather spectacularly (right). Motivation Analysis of the electrostatic breakdown for the material Low Density Polyethylene (LDPE) shows little or no temperature dependence in the range from -110 ºC to 25 ºC. Previous results for Kapton HN show an exponential increase in breakdown Why do we worry about the temperature dependent electrostatic discharge voltage with decreasing temperature in this range [Arnfield]. (breakdown) of polymeric insulators? 8500 Spacecraft Charging: plasma-induced charging due to interactions with the Breakdown Data Figure 9. Basic schematic of ESD test Figure 10. Typical Current vs voltage space environment account for almost half of all spacecraft failures and 8000 Exponential Fit circuit. measurements for 27 µm thick LDPE. anomalies. Average room temperature breakdown 7500 Modern communications systems and a myriad of products we use today rely Tests were conducted in a custom, high vacuum chamber designed by the Utah State 7000 critically on the use of spacecraft technology. The majority of spacecraft operate University Materials Physics Group (Fig. 11). Low temperature ESD measurements from ~120 f(x) = 6261.4 + 36.9·exp(-0.04·x) in a geosynchronous orbit, a distance from Earth not feasibly accessible for 6500 K were conducted by first cooling the samples with liquid nitrogen using an aluminum Breakdown Voltage (V) BreakdownVoltage repair. reservoir in thermal contact with the sample mounting plate and monitored with 6000 thermocouples attached to two Cu temperature sensor in contact with the sample (Fig. 14). The James Webb Space Telescope -100 -80 -60 -40 -20 0 20 (JWST) (Fig. 1), being built by Temperature (C) NASA and the European Space Agency, will be operating in the L2 Figure 5. Electrostatic field breakdown strength of LDPE as a Figure 6. Electrostatic field breakdown strength of Kapton HN function of temperature in the range from -110 ºC to 25 ºC. Lagrange point, an even greater as a function of temperature in the range from -100 ºC to 25 9 Fits shows the mean of all data ±σ (non-temperature ºC. for [Arnfield]. distance of 1.5 10 m from the dependent fit) and a linear temperature fit. Earth, at temperatures as low as 30 K, and in an extreme plasma environment. Materials for JWST are the focus of this study. Figure 1. James Webb Space Telescope. Comparison to Theory and Previous Studies Interaction with the plasma environment induces spacecraft charging, leading Cline et al. predict a model (at right) for the mean time to failure or Figure 11. USU Electrostatic Discharge Figure 12. Exposed view of ESD sample k T − h t ∆G to charge build up on the craft and its internal components, and ultimately can endurance time, t , as a function of high electric field, F, and B 1 en en FESD = csc h exp Chamber. assembly. (1) Cu thermocouple mount, (2) cause electrostatic breakdown. Electron, ion, and photon charge-induced 3 λ temperature, T [Dang]. The model has two parameters: the qe (4 ) kBT kBT Sample and mounting plate, 3) High voltage potentials can result in current spikes in the circuits or arcing (Fig. 2), thus maximum size of submicrocavities, λ, and the change in Gibbs electrodes. damaging electronics, solar panels (Fig. 3), or other spacecraft components. free energy, ΔG, for a rupture of interchain van der Waals bonds or Understanding how charge migration and dissipation occurs in insulators is the activation energy of the chain deformation or micro-void crucial to mitigating the effects of spacecraft charging. formation process [Griffiths]. The transition probability to break an interchain bond is equal to the reciprocal of the endurance time, P=1/ten. P also corresponds to the mean hop frequency; thus, h/ten can be thought of as the quantum energy uncertainty for a broken bond. At breakdown, the energy gained from electron motion through the electric field across a micro-void of width λ, qeFESDλ, is just sufficient to overcome the barrier height ΔG. Figure 13. Current and voltage interfaced Figure 14. Interior view of ESD sample assembly. meters. (1) Cryogen reservoir, (2) Sample mounting plate, (3) Electrode plate with 2 sets of 3 high voltage copper electrodes and a Cu thermocouple Figure 2. High energy radiation Figure 3. ESD event lead to severe mount, (4) Polycarbonate insulating base. deposits charge, causing internal damage of this solar array. discharge. Future Work References Future research will collect more data between room temperature and the existing data, Figure 8. Temperature dependence of the electrostatic field and at temperatures above room temperature. Along with additional temperature data, • D. Arnfield and JR Dennison, ”Temperature Dependence of Kapton HN Breakdown Voltages,” Utah State University Student breakdown strength. (a) Endurance, or time to breakdown, tests will be done to determine the endurance time dependence of electrostatic Showcase, Logan, UT, April 2, 2008. breakdown. Comparison to the endurance time model hopefully will allow determination of • JR Dennison, Alec Sim, Jerilyn Brunson, Steven Hart, Jodie Gillespie, Justin Dekany, Charles Sim and Dan Arnfield, “Engineering as a function of applied electric field. Curves shown are for Tool for Temperature, Electric Field and Dose Rate Dependence of High Resistivity Spacecraft Materials Paper Number,” AIAA-2009- temperature set to 150 K (purple), 200 K (blue), 250 K the micro-void width, λ, and the change in Gibbs free energy, ΔG, of LDPE for direct 0562, Proceedings of the 47th American Institute of Aeronautics and Astronomics Meeting on Aerospace Sciences, 2009. (green), 300 K (orange) and 400 K (red). (b) Breakdown field • C.L. Griffiths, J. Freestone, R.N. Hampton, “Thermoelectric Aging of Cable Grade XLPE,” Conf. Record of IEEE International comparison with similar results from dark current conductivity, radiation induced Symposium on Electrical Insulation, Arlington, VA, 1998, pp. 578-582. strength as a function of temperature. Curves shown are conductivity and electron emission measurements at USU. • C. Dang, J.-L. Parpal, J.P. Crine, “Electrical Aging of Extruded Dielectric Cables: Review of Existing Theory and Data,” IEEE Trans. Figure 7. The graph above shows the measured breakdown endurance times set to 100 s (purple), 102 s (blue), 104 s or Dielectrics and Insulators, Vol. 3, No. 2, April 1996, 237-247. 6 8 • Sabuni and Nelson, J. Mat. Science 12, 2435-2440 (1977). voltages and their estimated error for various polymers. 2.8 hr (green), 10 s or 12 days (orange) and 10 s or 3.2 yr • K. Shinyama, S. Fujita; Int. J. Soc. Mater. Eng. Resour. 13, 2 (Mar 2006)]. [Shinyama] Our data (red) extend these measurements to low (red). To approximately match LDPE data, we have set Research was supported by a Utah State University Undergraduate Research and Creative • Anthony Thomas, JR Dennison, Steve Hart and RC Hoffmann, “The Effect of Voltage Ramp Rate on Dielectric Breakdown of Thin 8 Opportunities grant and funding from the NASA/JWST Electrical Systems Working Group at Goddard temperature. FESD=9.5·10 V/m and ΔG=1.22 eV. [Dennison]. Film Polymers,’ American Physical Society Four Corner Section Meeting, Utah State University, Logan, UT, October 6-7, 2006.
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