10-pF Vacuum-Dielectric Standard Capacitor

Vacuum-dielectric standard capacitor based on a quasi-monolithic concept is developed. The capacitive element is composed of two monolithic coaxial cylinders, but the capacitance is only governed by the dimensions of the inner cylinder. TiO
₂
-doped fused silica with low thermal expansion coefficient is used as the structural material. The expected capacitance stability is about 0.2 aF per year and the temperature coefficient is about 5·10
^-8
/K.