A left-handed material extended interaction klystron includes: an input cavity, a middle cavity, an output cavity, first-section drift tube and a second-section drift tube; wherein the input cavity, the middle cavity and the output cavity are all cylindrical resonant cavities having arrays of Complementary electric Split-Ring Resonator (CeSRR) unit cells provided therein; wherein a first side of the input cavity is an input channel of an electron beam, a second side connects the middle cavity via the first-section drift tube; a first T-shaped coaxial input structure is provided in the input cavity; a first side of the output cavity is for connecting a collector, a second side of the output cavity connects the middle cavity via the second-section drift tube, a second T-shaped coaxial output structure is provided in the output cavity.

A beam current measuring device capable of performing measurement of a beam current distribution of a charged particle beam seamlessly and continuously in an arbitrary direction is provided. The beam current measuring device includes collector electrodes whose detection regions seamlessly continue in an arrangement direction thereof.

A beam current measuring device capable of performing measurement of a beam current distribution of a charged particle beam seamlessly and continuously in an arbitrary direction is provided. The beam current measuring device includes collector electrodes whose detection regions seamlessly continue in an arrangement direction thereof.

According to one embodiment, a klystron device includes a klystron body and a focusing magnetic field device. The klystron body has an electron gun section, a collector section, a plurality of cavity resonators, and a plurality of drift tubes. The cavity resonators have nose sections that face each other in an axial direction and form a gap section that is connected to the drift tubes. At least one of the cavity resonators has an electric field correction section in a part of the nose section that makes a space of the gap section different with respect to a space between the nose sections.

According to one embodiment, a klystron device includes a klystron body and a focusing magnetic field device. The klystron body has an electron gun section, a collector section, a plurality of cavity resonators, and a plurality of drift tubes. The cavity resonators have nose sections that face each other in an axial direction and form a gap section that is connected to the drift tubes. At least one of the cavity resonators has an electric field correction section in a part of the nose section that makes a space of the gap section different with respect to a space between the nose sections.