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  • 1.
    Goryashko, Vitaliy A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Yogi, Rutambhara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    A megawatt class compact power combiner for solid-state amplifiers2014In: Journal Electromagnetic Waves and Applications, ISSN 0920-5071, E-ISSN 1569-3937, Vol. 28, no 18, p. 2243-2255Article in journal (Refereed)
    Abstract [en]

    We propose a compact multiport two-stage combiner capable of handling peak power up to 10MW at the UHF band and suitable for particle accelerator applications. The detailed electromagnetic and thermal simulations of the combiner operating at the ESS specifications of 400kW at 352MHz are presented. At the first stage, the power is combined to a 100kW level by means of a non-resonant 12-way radial combiner, which is assumed to be fed by 8kW solid-state amplifiers. At the second stage, a waveguide combiner with T-shape couplers separated by a half-wavelength of the fundamental waveguide mode is used in order to bring the combined power to the required level. The combiner is broadband and has a relative power non-uniformity less than 5% over a 10MHz frequency band around the central frequency. The size of the proposed combiner is several times smaller than the existing ones. We also present low-power measurement results of a prototype of the radial combiner.

  • 2.
    Goryashko, Vitaliy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gajewski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Johansson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lofnes, Tor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Noor, Masih
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Santiago-Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Wedberg, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Yogi, Rutambhara A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Proposal for Design and Test of a 352 MHz Spoke RF Source2012Report (Other academic)
    Abstract [en]

    More than a dozen of spoke resonators prototypes (SSR, DSR, TSR) have been constructed and tested worldwide. None have accelerated beam until now and the ESS LINAC will be the first accelerator to operate with spoke cavities. Experience with other types of superconducting cavities indicates that high-power test is vital for reliable operation of the cavity in an accelerator. Although characteristics of a bare cavity can be obtained in a low-power test some important features of a `dressed' cavity like the electroacoustic stability and tuning system can be studied only in a high-power test stand. The ESS LINAC is a pulsed machine and the Lorentz detuning originating from the electromagnetic pressure on the cavity walls is expected to be strong. The Lorentz force along with the cavity sensitivity to mechanical excitations at some resonant frequencies may lead to self-sustained mechanical vibrations which make cavity operation dicult. Practical experience shows that increasing the boundary stiness will decrease the static Lorentz force detuning but not necessarily the dynamic one. Therefore, the FREIA group at Uppsala University is building a high-power test stand able to study performance of the ESS spoke cavity at high power. The RF test stand will be able to drive the cavity not only in the self-excitation mode but also with closed RF loop and fixed frequency. The later technique will be used to reproduce the shape of the cavity voltage pulse as it is expected to be in the cavity operating in the ESS LINAC such that the cavity tuning compensation system will be tested under realistic conditions.

  • 3.
    Olvegård, Maja
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Bhattacharyya, Anirban
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Eriksson, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Fransson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Gajewski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Holz, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Jacewicz, Marek
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Jobs, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Jönsson, Åke
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Li, Han
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lofnes, Tor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Nicander, Harald
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Santiago Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Wedberg, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Yogi, Ruthambara
    European Spallation Source.
    PROGRESS AT THE FREIA LABORATORY2015In: Proceedings of IPAC'15, JACoW: The Joint Accelerator Conferences Website , 2015Conference paper (Refereed)
    Abstract [en]

    The FREIA Facility for Research Instrumentation and Accelerator Development at Uppsala University, Sweden, has reached the stage where the testing of superconducting cavities for the European Spallation Source (ESS) is starting. The new helium liquefaction plant has been commissioned and now supplies a custom-made, versatile horizontal cryostat, HNOSS, with liquid helium at up to 140 l/h. The cryostat has been designed and built to house up to two accelerating cavities, or, later on, other superconducting equipment such as magnets or crab cavities. A prototype cavity for the spoke section of the ESS linac will arrive mid 2015 for high-power testing in the horizontal cryostat. Two tetrode-based commercial RF power stations will deliver 400 kW peak power each, at 352 MHz, to the cavity through an RF distribution line developed at FREIA. In addition, significant progress has been made with in-house development of solid state amplifier modules and powercombiners for future use in particle accelerators. We report here on these and other ongoing activities at the FREIA laboratory.

  • 4.
    Ruber, Roger
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Yogi, Rutambhara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gajewski, Konrad
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Jacewicz, Marek
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Lofnes, Tor
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Santiago Kern, Rocio
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Wedberg, Rolf
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Tests of the Spoke Cavity RF Source and Cryomodules in Uppsala: ESS TDR Contribution2012Report (Other academic)
  • 5.
    Wedberg, Rolf
    et al.
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Yogi, Rutambhara A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Santiago-Kern, Rocio
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Lofnes, Tor
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gajewski, Konrad
    Uppsala University, The Svedberg Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Power Supplies for Tetrode High Power Amplfiers at FREIA: ESS TDR Contribution2012Report (Other academic)
    Abstract [en]

    This paper select the topology of the power supplies to the RF power amplifier to one spoke cavity to be tested at FREIA Uppsala University.The power supplies are thought to fulfill the requirements of ESS in Lund.

    The amplifiers pulsed operation will have a strong impact of the choice of topology. The RF amplifier will have two tetrodes in the final stage.

    The anode power supply is studied for different topologies and number of anodes to supply.

    Storing the energy for pulse current to the anodes at high voltage or at low voltage is considered.

    The short circuit protection can be with a crowbar or a series switch. The series switch is selected for reasons of short interrupts in case of temporary short circuits.

    The grid and filament supplies are thought to be standard of the shelf power supplies.

    Cost estimate and comments on maintenance in the end of the paper.

  • 6.
    Yogi, Rutambhara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Design of the RF Distribution System for the ESS Spoke Linac2013Report (Other academic)
    Abstract [en]

    Based on the known boundary conditions of cost, ionizing radiation and space, we propose a combination of coaxial lines and waveguides for the RF distribution system of the spoke linac. At full power level (400 kW peak) 6-1/8" coaxial lines are used in low radiation level zones while WR2300 half-height waveguide are used in high radiation level zones. At lower power levels and in low radiation zones 3-1/8" and 7/8" coaxial lines are used.

  • 7.
    Yogi, Rutambhara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Gajewski, Konrad
    Uppsala University, The Svedberg Laboratory.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Noor, Masih
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Wedberg, Rolf
    Uppsala University, The Svedberg Laboratory.
    Santiago-Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Lofnes, Tor
    Uppsala University, The Svedberg Laboratory.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Goryashko, Vitaly
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ruber, R J M Y
    CERN, Geneve, Schweiz.
    Uppsala high power test stand for ESS spoke cavities2012In: Proceedings of LINAC2012, 2012, p. 711-713Conference paper (Refereed)
  • 8.
    Yogi, Rutambhara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Wedberg, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Goryashko, Vitaliy
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Santiago-Kern, Rocio
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Hermansson, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Lofnes, Tor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Gajewski, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Dancila, Dragos
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Rydberg, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ziemann, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ekelöf, Tord
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Ruber, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Selection of RF Power Source and Distribution Scheme at 352 MHz for Spoke Cavities at ESS and FREIA2012Report (Other academic)
    Abstract [en]

    The report describes selection of RF power source and distribution scheme for spoke cavities at ESS and FREIA.  The European Spallation Source (ESS) is the world’s most powerful neutron source, which contain 36 superconducting spoke cavities at 352MHz and provide power of 0.5MW to the beam. The baseline for the RF system is a point-to-point generation and distribution  from a single source to a single accelerating cavity.The RF system that has to generate this power and distribute it to the accelerating cavities, is a main resource driver for linear accelerators in form of investment, operation and maintenance. Therefore the technical alternatives are compared to minimize capital and running cost of the accelerator, without compromising its reliability. At 352 MHz and 350 kW RF power output, tetrode amplifiers are selected because of their advantages of being cheap, reliable, simple and efficient as compared to the other RF power amplifiers. The tetrodes, due to their low gain, need a pre-driver. The solid state amplifier technology is selected as a pre-driver due to its simplicity, reliability and efficiency. Half height aluminum WR2300 wave guides shall be used for RF distribution. This solution makes it possible to discard the circulator from the RF distribution chain, thus improving system efficiency.

1 - 8 of 8
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