Lars Hermansson

Design of a horizontal test cryostat for superconducting RF cavities for the FREIA facility at Uppsala University

Uppsala University is constructing a large scale facility, called FREIA (Facility for Research Instrumentation and Accelerator Development). FREIA includes a helium liquefier and an accelerator test facility and has the capacity to test superconducting radio-frequency (RF) cavities with the same RF system and RF power level as in an accelerator. A central element of FREIA is a horizontal test cryostat connected in closed loop to a helium liquefier. This cryostat can house two fully equipped (tuners, piezo, power coupler, helium tank) superconducting cavities to perform full RF high power tests and operate at temperatures between 1.8 K and 4.2 K. The cryostat is designed to accommodate a large array of superconducting cavities and magnets, among which the European Spallation Source (ESS) type spoke and high-β elliptical cavities as well as TESLA/ILC type elliptical cavities. The present status of the project and the design of the cryostat are reported.

Tetrode Based Technology Demonstrator at 352 MHz, 400 kWp for ESS Spoke Linac

The European Spallation Source (ESS) will be the worlds most powerful spallation neutron source when it comes in operation at the end of this decade. The ESS linac will accelerate 50mA of protons to 2 GeV in 2.86 ms long pulses at a repetition rate of 14 Hz on a tungsten target for neutron spallation. The linac contains 26 superconducting spoke cavities, which are being developed by IPN Orsay, France, and which accelerate the protons from 90 to 220 MeV. The FREIA laboratory at Uppsala University (Sweden) has developed the required RF power sources, procured the RF distribution and will test the cavities at nominal power. As no suitable amplifier was available at the ESS specifications (352MHz, 400kWp / 20kWavg, pulse width = 3.5 ms, pulse repetition frequency = 14 Hz), various technologies were compared and tetrode technology was selected for the first technology demonstrator RF power station at FREIA. We discuss the design of the technology demonstrator and present the first test results.

ESS Superconducting RF Collaboration

The European Spallation Source (ESS) project is a neutron-scattering facility, currently under construction by a partnership of at least 17 European countries, with Sweden and Denmark as host nations. The ESS was designated a European Research Infrastructure Consortium, or ERIC, by the European Commission in October of 2015. Scientists and engineers from 50 different countries are members of the workforce in Lund who participate in the design and construction of the European Spallation Source. In complement to the local workforce, the superconducting RF linear accelerator is being prototyped and will be constructed based on a collaboration with European institutions: CEA-Saclay, CNRS-IPN Orsay, INFN-LASA, STFC-Daresbury, Uppsala and Lund Universities. After a description of the ESS collaborative project and its in-kind model for the SRF linac, this article will introduce the linac component first results.