Quick report on HV testing of Fiber- Reinforced Plastic (FRP): - PowerPoint PPT Presentation

Quick report on HV testing of Fiber- Reinforced Plastic (FRP): delamination seen Jennifer Tyler Glenn Horton-Smith 2016-07-13

Reminder: Two-sided charge-up Electric potential Uniformly charged surface in external field ● Charged ● Analytic form confirms dependence on aspect ratio for w/d >> 1. ● High fields at corners: analytical expression gives logarithmic Bo's simulation of surface charged until field canceled at surface divergence of E at corners

Effect of bulk resistance? ● Current Flux J = (Field) / (Resistivity) ● To limit internal field in material to some amount E max , corresponding resistivity is E max / J. ● For 4” box-beam with 1/4” walls centered in 40 cm gap, exterior drift is 15 cm, interior is 10 cm. ● different charge-up currents, slightly higher field inside box channel at equilibrium ● J ~ 20 pA/m 2 ● To limit E max < 10 kV/cm, need resistivity less than (10e3 V/cm)/(2.4e-15 A/cm^2) = 4e18 ohm-cm. ● To keep field above 500 V/cm, need resistivity greater than 2e17 ohm-cm . ● These resistances are all way larger than lower limits given by vendors...

We have been measuring current through 12”x12”x1/4” FRP Stainless plate 20 G Conductive foam + V FRP sample - I Keithley electrometer

We have interesting results we will describe in more detail later ● Bulk resistivity – apparently in the range we want ● Apparent hysteresis in charging complicates analysis – Weirdly consistent with a ferroelectric effect (?); we are still checking for instrumental effects ● Clear observation of delamination of edges when HV applied! – Conditions: 2.8 kV applied over 11.5”x11.5” area of 12”x12” plate, 3 days and 0.5 day tests.

After 3 days at 2.9 kV (4.6 kV/cm)

After filing edge to clean and camfer, then 0.5 days at 2.9 kV