A receptacle for receiving a plug connector of a high-voltage cable for a microfocus X-ray tube with a cathode, which has a metal filament and grid. The receptacle has a ceramic insulator with three contiguous cavities. The first cavity near the filament includes electrical contacts for the filament and the grid. The second cavity includes spring contacts for supplying current to the filament and a center pin for supplying voltage to the grid. The third cavity receives the plug connector. The insulator has a removable grid cap which is conductively connected to the grid of the cathode. The first and second cavities are surrounded in the radial direction by the grid cap, An air gap extends radially between grid cap and ceramic body. At the end of the grid cap remote from the filament is a circumferential groove in the axial direction between the grid cap and the ceramic insulator.

A receptacle for receiving a plug connector of a high-voltage cable for a microfocus X-ray tube with a cathode, which has a metal filament and grid. The receptacle has a ceramic insulator with three contiguous cavities. The first cavity near the filament includes electrical contacts for the filament and the grid. The second cavity includes spring contacts for supplying current to the filament and a center pin for supplying voltage to the grid. The third cavity receives the plug connector. The insulator has a removable grid cap which is conductively connected to the grid of the cathode. The first and second cavities are surrounded in the radial direction by the grid cap, An air gap extends radially between grid cap and ceramic body. At the end of the grid cap remote from the filament is a circumferential groove in the axial direction between the grid cap and the ceramic insulator.

A spark gap comprising a cathode and an anode is provided. The spark gap is divided into two partial spark gaps by means of a central piece, namely a high-pressure spark gap and an effective spark gap. The effective spark gap can for example, be used to generate monochromatic x-rays. In order to guarantee a defined switching time, the high pressure spark gap which is initially switched to defined, is used. The switching initiates a potential so high on the centre piece that, when the high pressure spark gap is switched, the effective spark gap can also be switched in a defined manner without significant delays, to a visibly higher voltage.

A spark gap comprising a cathode and an anode is provided. The spark gap is divided into two partial spark gaps by means of a central piece, namely a high-pressure spark gap and an effective spark gap. The effective spark gap can for example, be used to generate monochromatic x-rays. In order to guarantee a defined switching time, the high pressure spark gap which is initially switched to defined, is used. The switching initiates a potential so high on the centre piece that, when the high pressure spark gap is switched, the effective spark gap can also be switched in a defined manner without significant delays, to a visibly higher voltage.