Ion generation device and ion implanter

An ion generation device comprising:

• an arc chamber including an internal space and including a front slit for extracting an ion beam from plasma generated in the internal space;
• a magnetic field generator that generates a magnetic field applied in an axial direction in the internal space;
• and
• a first cathode configured to supply a thermoelectron into the internal space,
• wherein the first cathode includes
• a first cathode cap that protrudes in the axial direction toward an inside of the arc chamber and emits the thermoelectron supplied into the internal space,
• a first heat source that heats the first cathode cap, and
• a first thermal shield including a first extension portion that extends in the axial direction in a substantially tubular shape on a radially outer side of the first cathode cap and is adjacent to the first cathode cap with a gap in a radial direction perpendicular to the axial direction, a first tip portion that protrudes toward the inside of the arc chamber, and a first tip opening that opens in the axial direction at the first tip portion, and
• a first opening width of the first tip opening in the radial direction is smaller than a maximum width of the first cathode cap in the radial direction.