| Paper | Title | Page |
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| WEPLS042 | Design and Experimental Investigation of an X-band Multilayer Dielectric Accelerating Structure | 2466 |
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| A new project to significantly improve the efficiency of high gradient DLA structures is presented. A multilayer DLA where the single dielectric layer is replaced by a multiple coaxial layers of differing permittivity have been developed. The power attenuation in the multilayer structure is reduced by the Bragg Fiber principle where the dielectric layers are used to create multiple reflections in order to confine the accelerating mode fields for the most part in the dielectric, reducing the axial current on the conducting outer boundary. A design for an X-band multilayer structure operating in the TM03 mode using alternating dielectric layers with permittivities of 38 and 9.7 is discussed. In order to transfer the RF from the rectangular waveguide to the cylindrical one at TM03 mode, a special coupling and mode conversion scheme was developed. A prototype structure has been constructed and bench test results of the multilayer 11.424 GHz accelerator is presented. | ||
| WEPLS039 | Developments on a Diamond-based Cylindrical Dielectric Accelerating Structure | 2460 |
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| Developments on a high gradient diamond-based cylindrical dielectric loaded accelerator (DLA) is presented. A diamond-loaded DLA can potentially sustain accelerating gradients far in excess of the limits experimentally observed for conventional metallic accelerating structures. The electrical and mechanical properties of diamond make it an ideal candidate material for use in dielectric accelerators: high RF breakdown level, extremely low dielectric losses and the highest available thermoconductive coefficient. We used the hot-filament Chemical Vapor Deposition (CVD) process to produce high quality 5-10 cm long cylindrical diamond layers. Our collaboration has also been developing a new method of CVD diamond surface preparation that reduces the secondary electron emission coefficient below unity. Special attention was paid to the numerical optimization of the coupling section, where the surface magnetic and electric fields were minimized relative to the accelerating gradient and within known metal surface breakdown limits. | ||
| WEPLS040 | Progress towards an Experimental Test of an Active Microwave Medium Based Accelerator | 2463 |
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We have been working on an experimental test of the PASER concept, where an active medium is used to provide the energy for accelerating charged particles. Initial theoretical work in this area focused on acceleration at optical frequencies; however we have identified a candidate active material operating in the X-band: a solution of fullerene (C60) in a nematic liquid crystal has been found to exhibit a maser transition* in this frequency range. The ability to employ a microwave frequency material simplifies the construction of test structures and allows beam experiments to be performed with relatively large beam emittances. We will report results on synthesis and testing of the active material using EPR spectroscopy, design and numerical simulations of bench test structures and plans for future beam experiments.
*A. Blank et al. IEEE Trans. Microwave Theory and Techniques 46 (2137) 1998. |
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| THPCH195 | New Developments on Low-loss Ferroelectrics for Accelerator Applications | 3251 |
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| Recent results on development of BST (barium strontium titanium oxide composition) ferroelectric materials are presented to be used as the basis for new advanced technology components suitable for high-gradient accelerators. Ferroelectric materials offer significant benefits for linear collider applications, in particular, for switching and control elements where a very short response time of 10 ns can be potentially achieved. The applications include: fast active X-band and Ka-band high-power ferroelectric switches, high-power X-band, and L-band ferroelectric-based phase-shifters. The recently developed large diameter (11 cm) BST-based ferroelectric rings will be used at high pulse power (tens of megawatts) for the X-band components as well as at high average power (in the range of a few kilowatts) for the L-band phase-shifters, which are suitable for ILC applications. |