Is vacuum the best dielectric, meaning is its dielectric strength infi

1.	Is vacuum the best dielectric, meaning is its dielectric strength infinite ?
Answer» In principle, an absence of particles mean no breakdown. However, practical vacuum still has large number of particles of residual gases. In practice, only pressures lower than 10^-2 mbar can be considered to provide a real dielectric insulation. In such vacuum, free electrical charges under a sufficiently high force can produce ionization and breakdown of its insulation properties. Thus, the dielectric strength of vacuum is only about 20 kV/mm, better than air but lower than most solid dielectrics.

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Is vacuum the best dielectric, meaning is its dielectric strength infinite ?

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