Disclosed embodiments include vacuum electronic devices, methods of operating a vacuum electronic device, and methods of fabricating a vacuum electronic device. In a non-limiting embodiment, a vacuum electronics device includes a cathode and an anode. At least one focus grid is disposed between the cathode and the anode, and the at least one focus grid is physically disconnected from the cathode. The at least one acceleration grid is disposed between the cathode and the anode, and the at least one acceleration grid is further disposed adjacent the at least one focus grid. The at least one acceleration grid is physically disconnected from the cathode.

Disclosed embodiments include vacuum electronic devices, methods of operating a vacuum electronic device, and methods of fabricating a vacuum electronic device. In a non-limiting embodiment, a vacuum electronics device includes a cathode and an anode. At least one focus grid is disposed between the cathode and the anode, and the at least one focus grid is physically disconnected from the cathode. The at least one acceleration grid is disposed between the cathode and the anode, and the at least one acceleration grid is further disposed adjacent the at least one focus grid. The at least one acceleration grid is physically disconnected from the cathode.

Disclosed embodiments include vacuum electronic devices, methods of operating a vacuum electronic device, and methods of fabricating a vacuum electronic device. In a non-limiting embodiment, a vacuum electronics device includes a cathode and an anode. At least one focus grid is disposed between the cathode and the anode, and the at least one focus grid is physically disconnected from the cathode. The at least one acceleration grid is disposed between the cathode and the anode, and the at least one acceleration grid is further disposed adjacent the at least one focus grid. The at least one acceleration grid is physically disconnected from the cathode.

Disclosed embodiments include vacuum electronic devices, methods of operating a vacuum electronic device, and methods of fabricating a vacuum electronic device. In a non-limiting embodiment, a vacuum electronics device includes a cathode and an anode. At least one focus grid is disposed between the cathode and the anode, and the at least one focus grid is physically disconnected from the cathode. The at least one acceleration grid is disposed between the cathode and the anode, and the at least one acceleration grid is further disposed adjacent the at least one focus grid. The at least one acceleration grid is physically disconnected from the cathode.

An X-ray generation device which can be efficiently used is provided. The X-ray generation device has an electron gun, a target unit, a tubular portion, a reflected electron detector, and a coil unit. The target unit includes a plurality of targets and a plurality of mark portions having a predetermined relationship with the targets, wherein each mark portion having a surface area larger than a surface area of the target when said target unit is viewed from a direction which is normal to principal faces of the target unit.