High dielectric strength insulator

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SUMMARY

The discussion centers on selecting high dielectric strength insulator materials for an ion Thomson Parabola spectrometer. Participants evaluated options such as PBN (polycrystalline boron nitride) and mica, noting that PBN has excellent dielectric strength but is limited in sheet size, while mica's dielectric strength is reported variably, with some literature citing values over 100kV/mm. A successful solution was found using PTFE (polytetrafluoroethylene), which handled voltages up to +/-50kV without discharges through the insulator. The final design included a PTFE chassis to minimize gaps and manage voltage effectively.

PREREQUISITES
  • Understanding of dielectric strength and its importance in insulator materials.
  • Familiarity with ion spectrometry and the requirements for insulating materials in vacuum environments.
  • Knowledge of material properties, specifically regarding PBN and PTFE.
  • Experience with sourcing and evaluating engineering materials for specific applications.
NEXT STEPS
  • Research the dielectric properties of various insulating materials using MatWeb's Property Search.
  • Investigate advanced manufacturing techniques for producing larger sheets of boron nitride.
  • Explore the electrical characteristics and applications of PTFE in high-voltage environments.
  • Study the design considerations for vacuum chambers in relation to electrode configurations and insulation.
USEFUL FOR

Engineers, physicists, and researchers involved in the design and construction of ion spectrometers, as well as materials scientists focusing on high-performance insulating materials.

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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