Most radiation therapy machines are based on microwave linear accelerators. The majority of medical accelerators use frequencies in the S-band range. Having a compact accelerator allows for a wide range of treatments. The size and weight of the accelerator is substantially reduced if a higher frequency is used. X-band frequencies are suitable for such applications. The X-band accelerator technology has been used in high-energy as well as industrial applications. In the radiation therapy field, it is already implemented in some machines. The Mobetron an Intra-Operative Radiation Therapy (IORT) treatment system is one example. Another example is the Stereotactic Radiosurgery machine, the CyberKnife. The compactness of these machines required the use of an X-band accelerator. The basis for choosing the X-band technology in some of the medical machines is analysed. A review of the exiting medical applications is included. We also discuss the availability of other X-band components in the machine, including high-power RF sources.

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Applications of X-band technology in medical accelerators

An electron/positron linear collider with a center-of-mass energy between 0.5 and 1 TeV would be an important complement to the physics program of the LHC. The Next Linear Collider (NLC) is being designed by a US collaboration (FNAL, LBNL, LLNL, and SLAC) which is working closely with the Japanese collaboration that is designing the Japanese Linear Collider (JLC). The NLC main linacs are based on normal conducting 11 GHz rf. This paper will discuss the technical difficulties encountered as well as the many changes that have been made to the NLC design over the last year. These changes include improvements to the X-band rf system as well as modifications to the injector and the beam delivery system. They are based on new conceptual solutions as well as results from the R&D programs which have exceeded initial specifications. The net effect has been to reduce the length of the collider from about 32 km to 25 km and to reduce the number of klystrons and modulators by a factor of two. Together these lead to s...

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Progress in the Next Linear Collider Design

Dogan, Mustafa (Dogus Author) -- Conference full title: 5th International Particle Accelerator Conference, IPAC 2014; International Congress Center DresdenDresden; Germany; 15 June 2014 through 20 June 2014.

Conceptual design of an X-FEL facility using CLIC X-band accelerating structure

On the base of general approach we obtain some results that can be useful in the process of tuning of nonunifrom disc-loaded waveguides Our consideration has shown that simple values that characterize the detuning of the cells can be introduced only for the disc-loaded waveguide with parameters that change very slow In general case it is needed to conduct full numerical simulation of specific disc-loaded waveguide and obtain all necessary coupling coefficients After that one can start the tuning process on the base of bead-pull field distribution measurements

Electromagnetic fields in nonuniform disk-loaded waveguides

A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.

FEL proposal based on CLIC X-band structure

For more than ten years, we have been working on R&D for X-band accelerator structures for the JLC/NLC linear collider. Several types of Detuned (DS) and Damped Detuned Structures (DDS) have been successfully designed and fabricated. They have been experimentally tested at both low power and high power to characterize their mechanical and electrical properties. Recently we started developing a new type of damped detuned structure with optimized round-shaped cavities (RDDS). This paper discusses the special specifications, design methods, fabrication procedures, measurement technologies, and anticipated future improvements for all these structures.

Accelerator structure R&D for linear colliders

As a joint effort in the JLC/NLC research program, we have developed a new type of damped detuned accelerator structure with optimized round-shaped cavities (RDDS). This paper discusses some important R&D aspects of the first structure in this series (RDDS1). The design aspects covered are the cell design with sub-MHz precision, HOM detuning, coupling and damping technique and wakefield simulation. The fabrication issues covered are ultra-precision cell machining with micron accuracy, assembly and diffusion bonding technologies to satisfactorily meet bookshelf, straightness and cell rotational alignment requirements. The measurements described are the RF properties of single cavities and complete accelerator section, as well as wakefields from the ASSET tests at SLAC. Finally, future improvements are also discussed.

T.O. Raubenhemer

Papers

Accelerator structure R&D for linear colliders

Design, fabrication and measurement of the first rounded damped detuned accelerator structure (RDDS1)