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MOPRI058 | Metal Plasmonic Nanostructures Functionalized by Atomic Layer Deposition of MgO for Photocathode Applications | 739 |
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Funding: Euclid TechLabs LLC acknowledges support from the DOE SBIR program, grant No. DE-SC0009572. To create high current, long lasting electron sources capable of providing sub-ps bunches, new photocathode concepts are sought. Most recently, plasmonic nanostructured metal surfaces or flat metal surfaces activated by an ultrathin MgO are under great attention. We report on a photocathode design combining these two approaches. It consists of plasmonic Ag nanoparticles (NPs) functionalized by 3 MgO monolayers (MLs). Ag NPs were synthesized by an aerosol method and MgO was grown by atomic layer deposition (ALD). The NPs geometry was tuned to obtain broadband >50% absorption in the entire blue range as evidenced by UV-vis. spectroscopy. The WF of 3 MgO MLs/Ag NPs multilayer was reduced by 1 eV compared to bare NPs, from 5 to 4 eV, as evidenced by UPS and Kelvin probe. Reduction by 1 eV is maximal for this pair of materials, and agrees well with experimental and theoretical findings. While the effect on WF is indeed significant, a special handling protocol for Ag before depositing MgO is a must. It would preserve a clean Ag surface with a WF of nearly 4 eV to achieve 3 eV upon ALD of MgO. This and other issues are under study to promote photocathode applications. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI058 | |
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WEPRO008 | A Beam-driven Microwave Undulator for FEL | 1956 |
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Funding: DOE SBIR Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.* *A. Zholents, HBEB Workshop, Puerto-Rico, 2013. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO008 | |
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WEPRO118 | THz Radiation Generation in Multimode Wakefield Structures | 2248 |
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Funding: DOE SBIR A number of methods for producing sub-picosecond electron bunches have been demonstrated in recent years. A train of these bunches is capable of generating THz radiation via multiple mechanisms like transition, Cherenkov and undulator radiation. We propose to use a bunch train like this to selectively excite a high order mode in a dielectric wakefield structure. This allows us to use wakefield structures that are geometrically larger and easier to fabricate for beam-based THz generation. In this paper we present a THz source design based on this concept and experimental progress to date. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO118 | |
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WEPRI012 | Euclid Modified SRF Conical Half-wave Resonator Design | 2502 |
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Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302. The new low-beta conical Half-Wave Resonator (cHWR) is suggested for CW proton accelerators of new generation with relatively low beam loading, where frequency detune caused by microphonics and helium pressure fluctuations is essential. This particular design, considered in the paper, has operation frequency of 162.5 MHz, b=v/c=0.11, and is suitable for the first section of the PIP-II superconducting accelerator which is under development at Fermilab. The main idea of the cHWR design is to provide a self-compensation cavity design together with its helium vessel to minimize the resonant frequency dependence on external loads. A unique cavity side-tuning option is also under development. Niowave, Inc. proposed a series of cavity and helium vessel modifications to simplify their manufacturing. The whole set of numerical simulations has been generated to verify that the main parameters of the initial structure design were not affected by the proposed modifications. Here we present the main results of the cavity and helium vessel modified design. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI012 | |
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WEPRI078 | Development of a Quarter-wave Coaxial Coupler for 1.3 GHz Superconducting Cavities | 2675 |
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Superconducting ILC-type cavities have an rf coupler that is welded on. A detachable coupler will reduce conditioning time (can be conditioned separately), reduce cost and improve reliability. The problem with placing an extra flange in the superconducting cavity is creating a possible quench spot. Euclid Techlabs LLC designed a coupler and optimized its geometry that yielding an area on the surface with zero magnetic field (hence zero surface current). By placing a flange in that area we are able to avoid disturbing surface currents that typically lead to a quench. The coupler is optimized to preserve the axial symmetry of the cavity and rf field. The rf test results of this type coupler with a 1.3 GHz ILC-type single-cell cavity at Fermilab will be reported and discussed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI078 | |
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