Accelerator and cyclotron

An accelerator comprising:

• an inflector through which a beam entering from an ion source passes and which introduces the beam to an acceleration orbit,
• wherein the inflector includes a beam convergence unit configured to converge the beam passing through the inflector,
• wherein the acceleration orbit has a convoluted shape,
• the beam convergence unit generates an electric field in a beam passing area through which the beam passes, and
• an intensity of the electric field becomes weak toward a position corresponding to an outer side of the acceleration orbit, which has the convoluted shape, in a cross-section perpendicular to a traveling direction of the beam.

A cyclotron that accelerates a beam in a convoluted acceleration orbit, the cyclotron comprising:

• magnetic poles configured to generate a magnetic field in a direction perpendicular to the acceleration orbit;
• D-electrodes generating a potential difference, which accelerates the beam, in the acceleration orbit;
• and
• an inflector through which a beam entering in an incident direction perpendicular to the acceleration orbit passes and which bends the beam so as to introduce the beam to the acceleration orbit,
• wherein the inflector includes a beam convergence unit configured to converge the beam passing through the inflector,
• wherein the acceleration orbit has a convoluted shape,
• the beam convergence unit generates an electric field in a beam passing area through which the beam passes, and
• an intensity of the electric field becomes weak toward a position corresponding to an outer side of the acceleration orbit, which has the convoluted shape, in a cross-section perpendicular to a traveling direction of the beam.