Itelco-Electrosys 400 kW RF Station Site Acceptance Test

The manufactured and delivered Itelco-Electrosys 400 kW RF station was tested on site at FREIA, in Uppsala August 31 through September 4 2015. The station could successfully deliver continuous pulsetrains with a power-level up to 400 kW. Each of the stations 200 kW tetrode based amplifier sections were mounted with TH-595 tetrode tubes from Thales and tuned for optimal performance. The gain of the tetrode amplifiers were roughly 15 dB with some variation between the two amplifier sections andthe overall gain was approximately 85 dB maximum.Some droop and phase distortion on the combined output pulse was measured caused primarily by a limited response time of the screen-grid power supply

DB Science 400 kW RF Station Site Acceptance Test

The manufactured and delivered DB-Science 400 kW RF station was tested on site at FREIA during 2016. The station can successfully deliver continuous pulse-trains with a power-level up to 400 kW, however during most of the on-site measurements and testing the total combiner output power was limited to 360 kW due to unusually high G2 currents measured in one of the spare TH595 tetrode tubes used in the station. Each of the stations 200 kW tetrode based amplifier sections were mounted with TH595 tetrode tubes from Thales and tuned for optimal performance. The gain of the tetrode amplifiers were roughly 15 dB with some variation between the two amplifier sections and the overall gain was approximately 74 dB maximum. Amplitude and phase pulse variations were within the specified levels

Earth-field Compensation Coils for the Vertical Cryostat in FREIA

We describe the design and construction of coils to compensate the Earth magnetic field in the vertical cryostat in FREIA

Retro-Fitting Earth-Field Compensation Coils to the Vertical Cryostat GERSEMI in FREIA

We describe the design and construction of coils to compensate the Earth’s magnetic field in the vertical cryostat GERSEMI in the FREIA laboratory at Uppsala University

Earth-field Compensation Coils for the Vertical Cryostat in FREIA

We describe the design and construction of coils to compensate the Earth magnetic field in the vertical cryostat in FREIA

Earth-field Compensation Coils for the Vertical Cryostat in FREIA

We describe the design and construction of coils to compensate the Earth magnetic field in the vertical cryostat in FREIA

400 kW RF Stations Operational Experience : Overview of the operation experience during 2018-2019 with the Itelco-Electrosys and DB Science stations at the FREIA Laboratory

We present the operational experience with the Itelco-Electrosys and DB Science 400 kW RF stations installed at the FREIA Laboratory. From the summer of 2018 to the summer of 2019 the stations were used for the test of the spoke cryomodule prototype for ESS. Unfortunately multiple issues with both RF stations delayed or inhibited normal operation. The Itelco-Electrosys station was out-of-operation from October 2018 to June 2019, due to multiple issues, which took a long time to understand and solve

400 kW RF Stations Operational Experience : Overview of the operation experience during 2018-2019 with the Itelco-Electrosys and DB Science stations at the FREIA Laboratory

We present the operational experience with the Itelco-Electrosys and DB Science 400 kW RF stations installed at the FREIA Laboratory. From the summer of 2018 to the summer of 2019 the stations were used for the test of the spoke cryomodule prototype for ESS. Unfortunately multiple issues with both RF stations delayed or inhibited normal operation. The Itelco-Electrosys station was out-of-operation from October 2018 to June 2019, due to multiple issues, which took a long time to understand and solve

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

The European Spallation Source (ESS) will be the world's 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

RF Performance of the spoke prototype cryomodule for ESS

The European spallation source (ESS), as a world-class high power proton accelerator facility, will be the first one to adopt 26 double spoke resonators (DSR) at its low energy section. As a new superconducting accelerating structure, these DSRs are therefore considered as a key technology and challenge of the whole project. They will be the first D SRs in the world to be commissionedfor a high power proton accelerator. As a milestone, the first DSR prototype cryomodule for ESS project was successfully tested at the FREIA Laboratory. In this qualification of the prototype cryomodule, the whole chain of RF station, RF distribution, fundamental power coupler (FPC), DSRs, cold tuning system (CTS) and low level radio frequency (LLRF) system, as well as the testing procedure have been verified on preparation for the industrialized cryomodules. Both cavities in the prototype cryomodule achieved nominal accelerating gradient, with the maximum gradient of 15 MV/m and 10.5 MV/m for cavity 1 and cavity 2 respectively. Based on the calorimetrical method, the dynamic heat load measurement showed that the cavity power consumption is around 0.5 W and therefore the intrinsic quality factor is consistent with the vertical test. This report presents the test configuration, RF conditioning history and first high power performance of this cryomodule