Status of Nb-Pb superconducting RF-GUN cavities
ABSTRACT We report on the progress and status of an electron RF* gun made of two superconductors: niobium and lead . The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead. The design of RF-gun and performance of 3 test cavities without and with the emitting lead spot are reported in this contribution. Measured quantum efficiency for lead at 2 K is presented briefly. More details are reported in .
Full-textDOI: · Available from: Triveni Rao, May 30, 2015
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ABSTRACT: Keywords: free electron laser, linear accelerator, vacuum ultraviolet (VUV) source. The fabulous properties of the coherent radiation generated with the free electron lasers (FEL) gained broader perspective on the experimental capabilities in physics, chemistry, biology and medicine. They raise from the nanometer-ranged wavelength, femtosecond-ranged pulse duration and brightness in the range of 10 29 photons/(s·mrad 2 ·mm 2 ·0.1% bandwidth) accompanied by up to megahertz repetition frequency. Such a light source extends experimental capabilities in spectroscopy, photon counting, imagining, photo-induced material processing and warm dense plasma creation. We propose to settle a high average power VUV FEL facility POLFEL at the Andrzej Soltan Institute for Nuclear Studies in Świerk. POLFEL is planned as a node of the EuroFEL network of complementary facilities, recommended by ESFRI. The great weight of the synchrotron radiation studies in modern science and technology makes us recognize the next, fourth generation light source facility as an instrument which will effectively improve the impact of research being run in Poland. Presented concept benefits from the long and wide experience of Polish scientists and engineers involved in the FEL activities world wide. Here we present an the overview of the general layout of the planned facility, paying a special attention to its novel solutions. The ground breaking feature of POLFEL is a continuous wave (cw) or near-cw operation. It will be achieved with a linear superconducting (sc) accelerator fed with a low emittance sc-electron injector furnished with the thin film sc lead photocathode. There are three outstanding characteristics of the VUV radiation emitted by FEL, which are often named as its fundamental advantages: femtosecond pulse duration, huge peak brilliance and high average intensity. As the first two of them are adequately accounted in the existing facilities or those being in the advanced phase of construction: FLASH, FERMI and LCLS, we turn our efforts towards the last of mentioned parameters – the average power. The principal goal, which dictates that approach, is to enable experiments requiring maximization of the time integrated number of interacting photons. They are experiments dealing with diluted samples and/or processes occurring with a low probability [1-3]. For those experiments, the significant improvement of experimental capabilities can be achieved when the recent progress in reduction of detectors readout time  goes together with the higher repetition rate of the light source. POLFEL will operate basing on the SASE (Self-Amplified Spontaneous Emission) principle  and will generate the light as displayed in Table 1.
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ABSTRACT: We report the efforts undertaken at NCBJ and some of its collaborating laboratories dedicated to prepare pure and flat lead films coated onto niobium to operate as superconducting photocathodes. Three approaches to lead cathodic arc deposition have been implemented and tested: active plasma flux filtering, passive filtering and unfiltered flux. None of them allowed us to find a proper balance between thickness and surface roughness of a cathode. At that point efforts were taken to establish post-deposition heat treatment of lead films.Proc SPIE 11/2013; 8903(89032B):89032B-1. DOI:10.1117/12.2035551