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[en] An R ampersand D RF cavity production and test program is underway to evaluate the practicality of superconducting RF cavity systems for future linear collider applications in the 500 GeV energy region. An international collaboration organized by DESY is assembling a TESLA test facility to assess gradient, systems, and manufacturing cost issues of the superconducting RF collider option. Construction of a state of the art cavity processing facility is underway. It is proposed to build four 12 m long cryounits each with eight 9-cell superconducting cavities operating at 1.3 GHz. Two 4.5 Mwatt, 2 msec pulse length klystrons will distribute power to the total 32 cavities. An electron gun and injector section will be included in this test facility, and beam tests with energies of about 500 MeV will be carried out
[en] Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement. Key aspects of high-current cw superconducting linac designs are explored in this context
[en] A new 9-cell shape is designed for Tev Superconducting Linear Accelerators (TESLA). The ratio of the maximal Surface electric field to the accelerating gradient, Epk/Eacc, was lowered down to 2.024 in the center cell while the cell to cell coupling is 1.95% for the 1.3 GHz accelerating mode. The properties of the higher order modes were investigated with a open-quotes dissipated band modelclose quotes
[en] We present a scheme of preparing the tripartite W state among three cavity modes of radiation field inside high-Q superconducting cavities. Our scheme is based on the interaction of a four-level atom with the cavity field for precalculated interaction times with every mode.
[en] Superconducting cavities are under operation or construction for acceleration of electrons and heavy ions at several laboratories. At present gradients around 5 MV/m, beam current up to 10 mA and operating experience exceeding 10,000 h are typical values. The advantage of superconducting RF is the high cw accelerating gradient, the low operating cost to establish RF voltage and the favorable cavity shape for a low loss factor. Ongoing progress in improving Niobium material, simplifying design and fabrication, understanding of performance limitations and investing cures against field emission promise to increase the operating gradient at reduced investment costs. High beam current applications are investigated to take advantage of the small higher order mode impedance. The most challenging development is the use of superconducting cavities for a TeV Linear Collider (TESLA)
[en] A precision method for measuring of ultrahigh unloaded Q factors of superconducting cavities is proposed which is based on the excitation of oscillation in the cavity by electron beam. In this measuring, the cavity is not connected to any external microwave circuit; its unloaded Q factor is determined from the loss of electron-beam power, which can be measured with high accuracy.
[en] Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities
[en] We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL-modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations. (Author) 6 figs., 5 tabs., 4 refs
[en] The full complement of 169 pairs of niobium superconducting cavities has been installed in the CEBAF accelerator. This paper surveys the performance characteristics of these cavities in vertical tests, commissioning in the tunnel, and operational experience to date. Although installed performance exceeds specifications, and 3.2 GeV beam has been delivered on target, present systems do not consistently preserve the high performance obtained in vertical dewar tests as operational capability. Principal sources of these limitations are discussed
[en] This paper briefly reviews the technical history of superconducting ion-accelerating structures. Various superconducting cavities currently used and being developed for use in ion linacs are discussed. Principal parameters and operational characteristics of superconducting structures in active use at various heavy-ion facilities are described