Fluid injector for X-ray tubes and method to provide a liquid anode by liquid metal injection

A fluid injector for x-ray tubes and a method to provide a liquid anode by liquid metal injection, wherein the fluid injector includes a device to inject fluid from an opening in a chamber of the device as a fluid jet generated by an arrangement to change the volume within the chamber, and includes a reservoir to store the anode material, which is fluidically connected by a pipe with the chamber of the device, where the pipe has a part formed in the fluid flow direction that is shaped to block fluid flow from the chamber to the reservoir during injection, and where the includes injecting fluid in a direction towards an electron beam and refilling the chamber with liquid metal from the reservoir.