The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure power... more The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure powered in reversed direction are presented. Powering the tapered structure from the small aperture, normally output, at the end of the structure provides unique conditions for the study of gradient limits. This allows high fields in the first cell for a comparatively low input power and a field distribution that rapidly falls off along the length of the structure. A maximum gradient of 130 MV/m in the first cell at a pulse length of 100 ns was reached for an input power of 31.9 MW. Details of the conditioning and operation at high-gradient are presented. Various breakdown rate measurements were conducted at different power levels and rf pulse widths. The structure was standard T24 CLIC test structure and was tested in Xbox-3 at CERN.
A Ferro-Electric fast Reactive Tuner (FE-FRT) is a novel type of RF cavity tuner containing a low... more A Ferro-Electric fast Reactive Tuner (FE-FRT) is a novel type of RF cavity tuner containing a low loss ferroelectric material. FE-FRTs have no moving parts and allow cavity frequencies to be changed extremely quickly (on the timescale of 100s of ns or less). They are of particular interest for SRF cavities as they can be placed outside the liquid helium environment and without an FE-FRT it's typically very difficult to tune SRF cavities quickly. FE-FRTs can be used for a wide variety of use cases including microphonics suppression, RF switching, and transient beam loading compensation. This promises entirely new operational capabilities, increased performance and cost savings for a variety of existing and proposed accelerators. An overview of the theory and potential applications will be discussed in detail.
Ion Beam Analysis (IBA) centres have provided researchers with powerful techniques to analyse obj... more Ion Beam Analysis (IBA) centres have provided researchers with powerful techniques to analyse objects of cultural significance in a non-destructive and non-invasive manner. However, in some cases it is not be feasible to remove an object from the field or museum and transport it to the laboratory. In this conference proceedings, we report the initial results of an investigation into the feasibility of a compact accelerator that can be taken to sites of cultural significance, for PIXE analysis. In particular, we consider the application of a compact, robust accelerator that is capable to producing 2 MeV protons that can be taken into the field to perform PIXE measurements on rock art. We detail the main challenges and considerations for such a device, as well as highlighting the potential benefits of this new accelerator application.
As part of the deign studies, the CompactLight project plans to use an injector in the C-band. Wh... more As part of the deign studies, the CompactLight project plans to use an injector in the C-band. Which constitutes a particular complication for the harmonic system in charge of linearising the beam's phase space, since it means its operation frequency could be higher than the standard X-band RF technologies. In the present work, we investigated a 36 GHz (Ka-band) as the ideal frequency for the harmonic system. A set of structure designs are presented as candidates for the lineariser, based on different powering schemes and pulse compressor technologies. The comparison is made both in terms of beam dynamics and RF performance. Given the phase stability requirements for the MW class RF sources needed for this system, we performed careful studies of a Gyro-Klystron and a multi-beam klystron as potential RF sources, with both showing up to 3 MW available power using moderate modulator voltages. Alternatives for pulse compression at Ka-band are also discussed in this work.
Although accelerator technology has matured sufficiently, state-of-the-art X-ray linacs for radio... more Although accelerator technology has matured sufficiently, state-of-the-art X-ray linacs for radiotherapy and cargo-scanning capture merely 30-50% of the electrons from a thermionic cathode, requiring a higher cathode current and leaving uncaptured electrons to cause problems due to back bombardment, shortening of cathode life, etc. Any solution to increase capture should be effective, simple, reliable, compact, and low cost in order to be adopted by industry. To address this, we present the design of a 6 MeV high capture efficiency S-band electron linac that captures 90% of the initial DC beam. This linac does not require any extra parts that would increase the cost as the high efficiency is achieved via a low-field-amplitude in the first bunching cell to decrease the number of backstreaming electrons, to velocity bunch the electron beam, and recapture backstreaming electrons. Under the low field amplitude, any electrons launched at decelerating phases travel backward with low speed...
A prototype Fast Reactive Tuner (FRT) for superconducting cavities has been developed, which allo... more A prototype Fast Reactive Tuner (FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a newly developed ultra-low loss ferro-electric material residing within the tuner. The tuner operates at room temperature, outside of the cryostat and coupled to the cavity via an antenna and co-axial cable. This technique allows for active compensation of microphonics, eliminating the need to design over-coupled fundamental power couplers and thus significantly reducing RF power particularly for low beam current applications. Modelling; simulation; and stability analysis, of the tuner; cavity; measurement system; and feedback loop, have been performed in the frequency and time domain, and are compared to the latest experimental results. The potential benefits of applying this techniques to ERLs, which are seen as one of the major use cases, are detailed both in general and with regards to specific project...
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