Cyclotron for accelerating charged particles around an axis, comprising an electromagnet with an upper pole and a lower pole, producing a magnetic field in the direction of said axis; a Dee electrode assembly and a counter Dee electrode assembly separated from each other by a gap for accelerating said charged particles and a pair of ion sources located in a central region of the cyclotron. Said ion sources are located at a distance of said axis such that the particles emitted from the first ion source pass between said first and second ion sources after a path of half a turn, and radially outwards of the second ion source after a path of three half-turns, and reciprocally.

Cyclotron for accelerating charged particles around an axis, comprising an electromagnet with an upper pole and a lower pole, producing a magnetic field in the direction of said axis; a Dee electrode assembly and a counter Dee electrode assembly separated from each other by a gap for accelerating said charged particles and a pair of ion sources located in a central region of the cyclotron. Said ion sources are located at a distance of said axis such that the particles emitted from the first ion source pass between said first and second ion sources after a path of half a turn, and radially outwards of the second ion source after a path of three half-turns, and reciprocally.

Ion beams are efficiently extracted with an accelerator that includes a circular vacuum container including a pair of circular return yokes facing each other. Six magnetic poles are radially disposed from the injection electrode at the periphery thereof in the return yoke. Six recessions are disposed alternately with the respective magnetic poles in the circumferential direction of the return yoke. In the vacuum container, a concentric trajectory region, in which multiple beam turning trajectories centered around the injection electrode are present, is formed, and an eccentric trajectory region, in which multiple beam turning trajectories eccentric from the injection electrode are present, is formed around the region. In the eccentric trajectory region, the beam turning trajectories are dense between the injection electrode and the inlet of the beam extraction path. Gaps between the beam turning trajectories are wide in a direction 180° opposite to the inlet of the beam extraction path.

Ion beams are efficiently extracted with an accelerator that includes a circular vacuum container including a pair of circular return yokes facing each other. Six magnetic poles are radially disposed from the injection electrode at the periphery thereof in the return yoke. Six recessions are disposed alternately with the respective magnetic poles in the circumferential direction of the return yoke. In the vacuum container, a concentric trajectory region, in which multiple beam turning trajectories centered around the injection electrode are present, is formed, and an eccentric trajectory region, in which multiple beam turning trajectories eccentric from the injection electrode are present, is formed around the region. In the eccentric trajectory region, the beam turning trajectories are dense between the injection electrode and the inlet of the beam extraction path. Gaps between the beam turning trajectories are wide in a direction 180° opposite to the inlet of the beam extraction path.

There is provided a circular accelerator that accelerates a beam of charged particles circulating in a magnetic field such that a closed orbit for each energy of the beam is eccentric. The circular accelerator includes a beam extraction port for extracting beams of different energies from the closed orbit, a first bending magnet and a second bending magnet that bend the beam extracted from the beam extraction port, and a control unit that controls magnetic field strengths of the first bending magnet and the second bending magnet in accordance with the energy of the extracted beam. When the energy of the extracted beam is a designed maximum energy of the circular accelerator, the control unit excites both the first bending magnet and the second bending magnet to bend the beam.

There is provided a circular accelerator that accelerates a beam of charged particles circulating in a magnetic field such that a closed orbit for each energy of the beam is eccentric. The circular accelerator includes a beam extraction port for extracting beams of different energies from the closed orbit, a first bending magnet and a second bending magnet that bend the beam extracted from the beam extraction port, and a control unit that controls magnetic field strengths of the first bending magnet and the second bending magnet in accordance with the energy of the extracted beam. When the energy of the extracted beam is a designed maximum energy of the circular accelerator, the control unit excites both the first bending magnet and the second bending magnet to bend the beam.

The present disclosure relates to a magnet pole for an isochronous sector-focused cyclotron having hill and valley sectors alternatively distributed around a central axis, Z, each hill sector having an upper surface bounded by four edges: an upper peripheral edge, an upper central edge, a first and a second upper lateral edges. The upper peripheral edge of a hill sector may be an arc of circle whose center is offset with respect to the central axis, and whose radius, Rh, is not more than 85% of a distance, Lh, from the central axis to a midpoint of the upper peripheral edge. Furthermore, the midpoint may be equidistant to the first and second upper distal ends.

The present disclosure relates to a magnet pole for an isochronous sector-focused cyclotron having hill and valley sectors alternatively distributed around a central axis, Z, each hill sector having an upper surface bounded by four edges: an upper peripheral edge, an upper central edge, a first and a second upper lateral edges. The upper peripheral edge of a hill sector may be an arc of circle whose center is offset with respect to the central axis, and whose radius, Rh, is not more than 85% of a distance, Lh, from the central axis to a midpoint of the upper peripheral edge. Furthermore, the midpoint may be equidistant to the first and second upper distal ends.

A particle beam therapy system is disclosed which includes: a synchrotron accelerating a charged particle beam injected from a pre-accelerator up to a predetermined energy level before applying a high-frequency voltage to an extraction device to extract the charged particle beam caused to exceed a stability limit; a beam transportation system transporting the charged particle beam extracted from the synchrotron up to a treatment room, and an irradiation device irradiating a patient in the treatment room with the charged particle beam in conformity to the patient's tumor shape. The synchrotron has functionality to accelerate or decelerate the charged particle beam successively to extract the charged particle beam at a plurality of energy levels during an extraction phase of the synchrotron, the beam transportation system further having functionality to block off an unnecessary charged particle beam extracted from the synchrotron during acceleration or deceleration.

A particle beam therapy system is disclosed which includes: a synchrotron accelerating a charged particle beam injected from a pre-accelerator up to a predetermined energy level before applying a high-frequency voltage to an extraction device to extract the charged particle beam caused to exceed a stability limit; a beam transportation system transporting the charged particle beam extracted from the synchrotron up to a treatment room, and an irradiation device irradiating a patient in the treatment room with the charged particle beam in conformity to the patient's tumor shape. The synchrotron has functionality to accelerate or decelerate the charged particle beam successively to extract the charged particle beam at a plurality of energy levels during an extraction phase of the synchrotron, the beam transportation system further having functionality to block off an unnecessary charged particle beam extracted from the synchrotron during acceleration or deceleration.