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

• Charged
• Analytic form confirms

dependence on aspect ratio for w/d >> 1.

• High fields at corners:

analytical expression gives logarithmic divergence of E at corners

Electric potential Uniformly charged surface in external field Bo's simulation of surface charged until field canceled at surface

Effect of bulk resistance?

• Current Flux J = (Field) / (Resistivity)
• To limit internal field in material to some amount Emax,

corresponding resistivity is Emax / 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/m2
• To limit Emax < 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

20 G I + V

• Keithley

electrometer Stainless plate Conductive foam FRP sample

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