An apparatus includes: a structure having a lumen for accommodating a beam, wherein the structure is a component of a medical radiation machine having a target for interaction with the beam to generate radiation; and a first beam position monitor comprising a first electrode and a second electrode, the first electrode being mounted to a first side of the structure, the second electrode being mounted to a second side of the structure, the second side being opposite from the first side; wherein the first beam position monitor is located upstream with respect to the target.

A field emission device is configured as a heat engine, wherein the configuration of the heat engine is variable.

A field emission device is configured as a heat engine, wherein the configuration of the heat engine is variable.

A vacuum tube for amplifier circuit includes: a light incidence window that transmits signal light; a photoelectric conversion unit that converts the signal light transmitted through the light incidence window into photoelectrons; an output unit that has an anode, on which the photoelectrons are incident, and outputs a signal corresponding to the incident photoelectrons; and a grid electrode that is disposed in a path of the photoelectrons from the photoelectric conversion unit to the anode and controls the amount of photoelectrons incident on the anode.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.

A device for controlling electron flow is provided. The device comprises a cathode, an elongate electrical conductor embedded in a diamond substrate, an anode, and a control electrode provided on the substrate surface for modifying the electric field in the region of the end of the conductor. A method of manufacturing the device is also provided.