High dielectric strength insulator

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Discussion Overview

The discussion focuses on the selection of high dielectric strength insulator materials suitable for use in an ion Thomson Parabola spectrometer. Participants explore various materials, their properties, and manufacturing limitations, particularly in relation to size and dielectric strength.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about suitable insulator materials, specifically mentioning PBN and mica, noting the limitations in size and dielectric strength availability.
  • Another participant suggests using MatWeb's Property Search to find alternative materials that may meet the specified requirements.
  • A different participant mentions that regular or hot pressed boron nitride is machinable and can achieve the necessary flatness, but still notes that the size limitation of 600mm is a challenge due to manufacturing capabilities.
  • One participant reports success using PTFE, indicating it can handle high voltages without discharges through the insulator, but mentions issues with discharges occurring between electrodes and a metal structure in the vacuum chamber.

Areas of Agreement / Disagreement

Participants express differing opinions on the suitability of various materials, with no consensus reached on the best option for the insulator. The discussion remains unresolved regarding the ideal material choice.

Contextual Notes

Participants highlight limitations related to the size of available materials and the dielectric strength reported in literature versus what is commercially available. There are also unresolved issues regarding the performance of materials under specific conditions.

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
 
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