| 1. |
- Bhattacharyya, Anirban, et al.
(författare)
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ESS RF Source and Spoke Cavity Test Plan
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes the test plan for the first high power RF source, ESS prototype double spoke cavity and ESS prototype cryomodule at the FREIA Laboratory.
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| 2. |
- Goryashko, Vitaliy, 1982-, et al.
(författare)
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Proposal for Design and Test of a 352 MHz Spoke RF Source
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 3. |
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| 4. |
- Li, Han, et al.
(författare)
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First High Power Test of the ESS Double Spoke Cavity
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The first double spoke cavity for ESS project was tested with high power in the HNOSS cryostat at FREIA Laboratory. This cavity is designed for 325.21MHz, a pulse mode with 14 Hz repetition rate, up to peak power of 360 kW. The qualification of the cavity package in a high power test, involved a spoke superconducting cavity, a fundamental power coupler, LLRF system and a RF station, represented an important verification before the module assembly. This report presents the test configuration, RF conditioning history and first high power performance of this cavity package.
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| 5. |
- Li, Han, et al.
(författare)
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First High Power Test of the ESS High Beta Elliptical Cavity package
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The first high-beta elliptical cavity for ESS project was tested with high power in the HNOSS cryostat at FREIA Laboratory. This cavity is designed for 704.42 MHz, a pulse mode with 14 Hz repetition rate, up to peak power of 1.5 MW. The qualification of the cavity package in a high power test, involved an elliptical superconducting cavity, a fundamental power coupler, cold tuning system, LLRF system and klystron system, represented an important verification before the module assembly. This report presents the test configuration, RF conditioning history and first high power performance of this cavity package.
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| 6. |
- Li, Han, et al.
(författare)
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RF Performance of the spoke prototype cryomodule for ESS
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 7. |
- Miyazaki, Akira, 1986-, et al.
(författare)
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First cold test of a crab cavity at the GERSEMI cryostat for the HL-LHC project
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.
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| 8. |
- Pepitone, Kevin, Dr, 1988-, et al.
(författare)
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First magnet operation on the cryogenic test stand Gersemi at FREIA
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Gersemi cryogenic test bench, installed at FREIA laboratory at Uppsala University, was used for the first time in 2021 to power a superconducting magnet. As part of the HL-LHC program, this cryostat offers an operating temperature between 4.2K and 1.9K. Its satellite equipment such as power converters and the acquisition system allow two superconducting magnet coils to be powered up to 2 kA and provide magnet protection through a robust quench detection and two energy extraction units. This report describes Gersemi's first cryogenic operational experiment and the safety strategy to ensure magnet integrity during operation.
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