A thermionic emission device includes an indirectly heatable main emitter, which is constructed as a flat emitter with a main emission surface, and at least one connectible heat emitter with a heat emission surface. The heat emission surface is disposed at a predefinable distance from the main emission surface. The main emission surface can be asymmetrically heated by the heat emission surface. In the operating state, the main emitter is at a main potential and the heat emitter is at a heating potential which differs from the main potential. An x-ray tube with the thermionic emission device has a longer service life with a consistent image quality.

A thermionic emission device includes an indirectly heatable main emitter, which is constructed as a flat emitter with a main emission surface, and at least one connectible heat emitter with a heat emission surface. The heat emission surface is disposed at a predefinable distance from the main emission surface. The main emission surface can be asymmetrically heated by the heat emission surface. In the operating state, the main emitter is at a main potential and the heat emitter is at a heating potential which differs from the main potential. An x-ray tube with the thermionic emission device has a longer service life with a consistent image quality.

An emitter includes an insulator, a pair of terminals attached to the insulator separately from each other, at least one filament attached between the pair of terminals in an arch shape, and an electron source fixed to the filament. The filament has bent portions between a contact with respect to the electron source and contacts with respect to the terminals. A device is provided with the emitter.

A thermionic emission device includes an indirectly heatable main emitter, which is constructed as a flat emitter with a main emission surface, and at least one connectible heat emitter with a heat emission surface. The heat emission surface is disposed at a predefinable distance from the main emission surface. The main emission surface can be asymmetrically heated by the heat emission surface. In the operating state, the main emitter is at a main potential and the heat emitter is at a heating potential which differs from the main potential. An x-ray tube with the thermionic emission device has a longer service life with a consistent image quality.

A thermionic emission device includes an indirectly heatable main emitter, which is constructed as a flat emitter with a main emission surface, and at least one connectible heat emitter with a heat emission surface. The heat emission surface is disposed at a predefinable distance from the main emission surface. The main emission surface can be asymmetrically heated by the heat emission surface. In the operating state, the main emitter is at a main potential and the heat emitter is at a heating potential which differs from the main potential. An x-ray tube with the thermionic emission device has a longer service life with a consistent image quality.

An indirectly heated cathode (IHC) ion source having improved life is disclosed. The IHC ion source comprises a chamber having a cathode and a repeller on opposite ends of the ion source. Biased electrodes are disposed on one or more sides of the ion source. The bias voltage applied to at least one of the cathode, the repeller and the electrodes, relative to the chamber, is varied over time. In certain embodiments, the voltage applied to the electrodes may begin at an initial positive voltage. Over time, this voltage may be reduced, while still maintaining the target ion beam current. Advantageously, the life of the cathode is improved using this technique.

An indirectly heated cathode (IHC) ion source having improved life is disclosed. The IHC ion source comprises a chamber having a cathode and a repeller on opposite ends of the ion source. Biased electrodes are disposed on one or more sides of the ion source. The bias voltage applied to at least one of the cathode, the repeller and the electrodes, relative to the chamber, is varied over time. In certain embodiments, the voltage applied to the electrodes may begin at an initial positive voltage. Over time, this voltage may be reduced, while still maintaining the target ion beam current. Advantageously, the life of the cathode is improved using this technique.

An indirectly heated cathode (IHC) ion source having improved life is disclosed. The IHC ion source comprises a chamber having a cathode and a repeller on opposite ends of the ion source. Biased electrodes are disposed on one or more sides of the ion source. The bias voltage applied to at least one of the cathode, the repeller and the electrodes, relative to the chamber, is varied over time. In certain embodiments, the voltage applied to the electrodes may begin at an initial positive voltage. Over time, this voltage may be reduced, while still maintaining the target ion beam current. Advantageously, the life of the cathode is improved using this technique.

An indirectly heated cathode (IHC) ion source having improved life is disclosed. The IHC ion source comprises a chamber having a cathode and a repeller on opposite ends of the ion source. Biased electrodes are disposed on one or more sides of the ion source. The bias voltage applied to at least one of the cathode, the repeller and the electrodes, relative to the chamber, is varied over time. In certain embodiments, the voltage applied to the electrodes may begin at an initial positive voltage. Over time, this voltage may be reduced, while still maintaining the target ion beam current. Advantageously, the life of the cathode is improved using this technique.

An emitter includes: an insulator; a pair of conductive terminals attached to the insulator and spaced apart from each other; a heater disposed between tips of the pair of conductive terminals and generating heat when energized; an electron source heated by the heater and made of a first material emitting electrons; a Wehnelt electrode having an inner surface forming an internal space apart with a surface of the insulator, and applying a bias voltage across the Wehnelt electrode and the electron source; and a shielding member covering a part of the surface of the insulator in the internal space.