High dielectric strength insulator

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For an ion Thomson Parabola spectrometer, suitable insulator materials include PBN and mica, but both have limitations in size and dielectric strength. PBN offers high dielectric strength but is difficult to source in larger sheets with proper flatness. Mica is easier to produce but typically has a maximum dielectric strength of around 30kV/mm, despite literature suggesting higher values. A user found success using high-quality PTFE, which handled voltages up to +/-50kV without discharges through the insulator. The user also addressed discharge issues by modifying the setup to reduce gaps between electrodes and a metal reinforcing pillar.
1Keenan
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Hello!

I would need advice on insulator material I can use for an ion Thomson Parabola spectrometer.
I would need to use an insulating sheet of 225x600x1,5mm and a smaller sheet of 100x100x1,5mm

I found PBN having an incredible dielctric strength, but seems like it cannot be manufactured in sheets bigger that 100x200 mm with proper flatness
MIca seems to be good as well and easier to produce, but I cannot find a supplier selling it with dielectrict strenght higher than 30kV/mm. In literature it is reported something like 100kV/mm and sometimes even more.

DO you have any suggestions?

THank you in advance
 
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Regular boron nitride or the hot pressed boron nitride is a machinable material, so the flatness is not a problem. However, 600mm is still too big, as the manufacturers don't have such a big hot presser. QS Advanced Materials have the largest boron nitride material in the market but is still at about 400mm.
 
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Hi,

Well, I solved with a good quality PTFE, I could apply up to +/-50 on both electrodes. Then I had discharges but not through the insulator. The happened between the electrodes and a metal reinforcing pillar in the vacuum chamber.
So I made a chassis with PTFE that also reduces the gap, and the voltage