Applications for high-voltage vacuum systems
High voltage insulation in vacuum

Vacuum breakdown found its first applications in the construction of vacuum electron tubes well before 1900, and was soon exploited in the construction of electron tubes (diodes, triodes, etc.) and vacuum spark gaps.

Spark gaps are fast switching circuits, typically with sub-nanosecond response times, and allow high currents to flow, typically up to 200 A. The most commonly used vacuum spark gap is direct current ( – DC), where the current starts with a field emission and the contact area passes through a spot limited to less than 1 mm ² . Spark gaps operating with radio-frequency (RF) excitation involve the capacitance of the entire cavity, which acts as a capacitor when empty. Breakdown in RF spark gaps depends not only on the electrode material, but also on the repetition rate, pulse length, etc.