Search

The SwissFEL Injector Test Facility at the Paul Scherrer Institute (PAI/Switzerland) started its operation in August 2010. This Facility represents the first stage of the 6 GeV acceleration complex foreseen for the SwissFEL X-Ray coherent light source planned at the PSI. The 250 MeV Injector consists of an S-Band RF photo injector followed by four S-Band acceleration structures of 4 m length each. For fine focusing corrections each accelerating structure is surrounded by four solenoids (WFS) of 0.8 m length and a maximum field of 0.1 T. Each solenoid consists of two coils in one yoke tube. To decrease the bunch length of the electron beam a magnetic bunch compressor chicane with four dipoles (AFBC2) providing a maximum magnetic field of 0.4 T for a length of 0.25 m was build. The central dipoles of the compressor chicane are sited on a movable girder to allow extensive compression studies with dipole angles between 0^\circ and 5^\circ. The preservation of a high brightness and a low emittance for the femto-second electron pulse impose severe tolerances in the field quality and in the magnet positioning. In this paper we review the design of two magnet types and discuss the results of field quality and magnetic axis measurements in terms of the specifications. [ABSTRACT FROM PUBLISHER]

A radiation therapy system using carbon ions is proposed. It is based on an accelerator system of two coupled cyclotrons. The first cyclotron accelerates carbon ions (or other particles) up to 250 MeV/nucl. The second cyclotron is used to boost these carbon ions to 450 MeV/nucl for treatments at deep tumor sites. This separate sector cyclotron consists of six sector 3.5 T magnets with superconducting coils and four RF cavities. We report on our first results of a feasibility study of the superconducting sector magnets of this booster cyclotron. To prevent concave magnet pole edges and to achieve symmetry in the design of the magnet, the introduction of a radial gradient in the sector is proposed. A magnet geometry based on a configuration with tilted coils is presented. The field strength varies from 2.8 T to 3.5 T over 0.8 m. The viability of the magnetic design is checked with tracking simulations. The distribution of the large electromagnetic forces acting on the coil winding, evaluated using a 3D finite element analysis, is reported. The details of the superconducting coil, of the type of wires, and of the cable layout are presented. The conceptual design of the cryostat and the options for conductor protection against quench are proposed. [ABSTRACT FROM AUTHOR]

The Paul Scherrer Institute (PSI/Switzerland) is developing, within the PROSCAN project, a new method of proton radiotherapy for treating cancers using a gantry based spot scanning technique for irradiating deep-seated tumors. Among the innovative elements are the laminated magnets in the beam lines, including the newly conceived Gantry 2, that will enable rapid energy changes (<150 ms) to modulate the range of the scanning pencil beam in three dimensions over the tumor volume. The last and multifunctional 90° bending magnet in the Gantry 2 transport system is not only the largest, but also the most challenging element. The dynamic eddy current effects during ramping were reduced with a special arrangement of laminated parts in the central pole region of the magnet. The construction of the Gantry 2 is finished and the first proton beam reached the treatment area in May 2008. The start of the patient treatment program is planned for the near future. In this paper, the 90° bending magnet construction and the results of the magnetic measurements (both static and dynamic) are presented, together with the commissioning experiences of the Gantry 2 magnet system. The results of the magnetic measurements validated the design, showing a very successful reduction of the eddy current effects so that the fast switching between two treatment energy steps (1 to 2% of the total energy) can be realized in less than 80 ms. [ABSTRACT FROM AUTHOR]

At the Paul Scherrer Institute (PSI/Switzerland) a new proton gantry for cancer treatment is planned. A fast 3 dimensional scanning technique of the tumor volume is one of the medical highlights of this new gantry. The gantry will be driven by the new COMET proton cyclotron, which will deliver a cw proton beam. The energy of this beam will be adjusted by a fast degrader device. All beam line magnets should follow the energy changes of the degrader as fast as possible. Therefore the eddy current effects in the laminated bending magnets of the beam line and the gantry must be reduced by an appropriate magnet design. The paper shows measurements and numerical simulation of the dynamic behavior of the fast switched bending magnets and design schemes for eddy current reduction in the bending magnets. [ABSTRACT FROM AUTHOR]