A low-erosion radio frequency ion source is disclosed having a hollow body with conductive interior walls that define a cylindrical cavity, with a gas supply inlet for plasma-forming gases and a power supply inlet for injecting radio frequency energy into the cavity; an expansion chamber connected to the cavity by means of a plasma outlet hole; an ion-extraction aperture in contact with the expansion chamber; coaxial conductor disposed in the cavity, parallel to the longitudinal axis thereof, one or both ends of the coaxial conductor being in contact with a circular interior wall of the body, forming a coaxial resonant cavity; the coaxial conductor having a conductive protuberance opposite the plasma outlet hole and which extends radially into the cavity. It substantially reduces the erosion of the conductive materials.

A low-erosion radio frequency ion source is disclosed having a hollow body with conductive interior walls that define a cylindrical cavity, with a gas supply inlet for plasma-forming gases and a power supply inlet for injecting radio frequency energy into the cavity; an expansion chamber connected to the cavity by means of a plasma outlet hole; an ion-extraction aperture in contact with the expansion chamber; coaxial conductor disposed in the cavity, parallel to the longitudinal axis thereof, one or both ends of the coaxial conductor being in contact with a circular interior wall of the body, forming a coaxial resonant cavity; the coaxial conductor having a conductive protuberance opposite the plasma outlet hole and which extends radially into the cavity. It substantially reduces the erosion of the conductive materials.

An accelerator includes: a plurality of ion sources 221, 222, and 233 that generate a plurality of different types of ions; an electromagnet 11 that generates a magnetic field; and a high frequency cavity 21 that generates a high frequency electric field. The center of an orbit of the ion is eccentric with acceleration, the magnetic field generated by the electromagnet 11 is a magnetic field distribution that decreases outward in a radial direction of the orbit, the high frequency cavity 21 accelerates the ion up to a predetermined energy by the high frequency electric field adjusted to an orbital frequency in response to a nuclide of the incident ion, and a frequency of the high frequency electric field changes following an energy of the ion. Accordingly, it is possible to provide an accelerator and a particle therapy system capable shortening an irradiation time with a small size.

An ECR (Electron Cyclotron Resonance) ion source includes a plasma chamber having a circular cylindrical cross-section, magnets for generating a magnetic field for confinement of the plasma in the plasma chamber, and a microwave generator disposed outside the plasma chamber and generating at least two microwave signals. Several antennas protrude radially into the plasma chamber with a predetermined angular offset α. The antennas receive phase-shifted microwave signals from the microwave generator and radiate linearly polarized microwaves, which in turn produce a circularly polarized microwave inside the plasma chamber. A method for operating an ECR ion source is also described.

In a circular accelerator that applies a radiofrequency wave in a main magnetic field to accelerate charged particle beam while increasing an orbit radius, another radiofrequency wave with a frequency different from the radiofrequency wave used for acceleration is applied to the charged particle beam in order to extract the charged particle beam. Thereby, in the circular accelerator that accelerates charged particle beam while increasing an orbit radius by applying a radiofrequency wave in a main magnetic field, the high precision control on extraction of the charged particle beam from the circular accelerator is achieved.

A system and method for injecting an electron beam to an accelerator are provided. The system may include a cathode, an anode, and a modulation electrode. The cathode, for generating the electron beam, may have a first electrical potential. The anode may have a second electrical potential. The modulation electrode, located between the cathode and the anode, may be configured to adjust at least one parameter of the electron beam. The at least one parameter of the electron beam may include at least one transverse parameter of the electron beam.

A system and method for injecting an electron beam to an accelerator are provided. The system may include a cathode, an anode, and a modulation electrode. The cathode, for generating the electron beam, may have a first electrical potential. The anode may have a second electrical potential. The modulation electrode, located between the cathode and the anode, may be configured to adjust at least one parameter of the electron beam. The at least one parameter of the electron beam may include at least one transverse parameter of the electron beam.

A wafer-based charged particle accelerator includes a charged particle source and at least one RF charged particle accelerator wafer sub-assembly and a power supply coupled to the at least one RF charged particle accelerator wafer sub-assembly. The wafer-based charged particle accelerator may further include a beam current-sensor. The wafer-based charged particle accelerator may further include at least a second RF charged particle accelerator wafer sub-assembly and at least one ESQ charged particle focusing wafer. Fabrication methods are disclosed for RF charged particle accelerator wafer sub-assemblies, ESQ charged particle focusing wafers, and the wafer-based charged particle accelerator.

A wafer-based charged particle accelerator includes a charged particle source and at least one RF charged particle accelerator wafer sub-assembly and a power supply coupled to the at least one RF charged particle accelerator wafer sub-assembly. The wafer-based charged particle accelerator may further include a beam current-sensor. The wafer-based charged particle accelerator may further include at least a second RF charged particle accelerator wafer sub-assembly and at least one ESQ charged particle focusing wafer. Fabrication methods are disclosed for RF charged particle accelerator wafer sub-assemblies, ESQ charged particle focusing wafers, and the wafer-based charged particle accelerator.

Technology is described for an electron gun driver including a half bridge driver circuit and a drive controller. The half bridge driver circuit includes a drive circuit configured to generate a grid drive voltage for a grid connection of an electron gun, and a cutoff circuit configured to generate a grid cutoff voltage for the grid connection of the electron gun, and a gate driver configured to switch between the grid drive voltage and the grid cutoff voltage. The drive controller is configured to generate a pulse input to the drive circuit and cutoff circuit and grid switching signals for the gate driver.