Abstract: The present disclosure addresses the problem of providing an electron gun that can directly monitor an intensity of an electron beam emitted from a photocathode using only the configuration provided to the electron gun, an electron beam applicator equipped with an electron gun, and a method for controlling an electron gun. The aforementioned problem can be solved by an electron gun comprising a light source, a photocathode that emits an electron beam in response to receiving light from the light source, an anode, an electron-beam-shielding member with which it is possible to shield part of the electron beam, and a measurement unit that measures the intensity of the electron beam emitted from the photocathode using a measurement electron beam shielded by the electron-beam-shielding member.

Abstract: An object is to provide an electron gun that makes it possible to verify whether or not an electron beam emitted form a photocathode is misaligned from a designed emission center axis. The object can be achieved by an electron gun including: a light source; a photocathode; and an anode. The electron gun includes an intermediate electrode arranged between the photocathode and the anode, an electron beam shielding member configured to block a part of an electron beam, a measurement unit configured to measure an intensity of an electron beam blocked by the electron beam shielding member, and an electron beam emission direction deflector arranged between the anode and the electron beam shielding member and configured to change a position where an electron beam that passed through the anode reaches the electron beam shielding member. The intermediate electrode has an electron beam passage hole and a drift space.

Abstract: Provided is a photocathode kit that does not require adjustment of the distance between a photocathode film and a lens focusing on the photocathode film when the photocathode and the lens are installed inside an electron gun. The photocathode kit includes: a photocathode including a substrate in which a photocathode film is formed on a first surface; a lens; and a holder that holds the substrate and the lens, and the holder has a retaining member that retains the photocathode film and the lens to be spaced apart by a predetermined distance, and a first communication path that communicates between inside of the holder and outside of the holder.

Abstract: The present invention addresses the problem of providing a device with which it is possible to adjust the focal point of an electron beam both toward a shorter focal point and toward a longer focal point after an electronic gun was fitted on a counterpart device. The aforementioned problem can be solved by an electron gun including a photocathode, and an anode, the electron gun furthermore comprising an intermediate electrode disposed between the photocathode and the anode, the intermediate electrode comprising an electron-beam passage hole through which an electron beam released from the photocathode passes, and the electron-beam passage hole having formed therein a drift space in which, when an electrical field is formed between the photocathode and the anode due to application of a voltage, the effect of the electrical field can be disregarded.

Abstract: The present invention addresses the problem of providing a device with which it is possible to adjust the focal point of an electron beam both toward a shorter focal point and toward a longer focal point after an electronic gun was fitted on a counterpart device. The aforementioned problem can be solved by an electron gun including a photocathode, and an anode, the electron gun furthermore comprising an intermediate electrode disposed between the photocathode and the anode, the intermediate electrode comprising an electron-beam passage hole through which an electron beam released from the photocathode passes, and the electron-beam passage hole having formed therein a drift space in which, when an electrical field is formed between the photocathode and the anode due to application of a voltage, the effect of the electrical field can be disregarded.