Vertical Test Facility Research Articles

Commissioning and cryogenic performance of the UKRI STFC Daresbury Vertical Test Facility for jacketed SRF cavities

A novel vertical test facility has been developed at the STFC Daresbury Laboratory. The cryostat is designed to test 3 jacketed superconducting RF cavities in a horizontal configuration in a single cool-down run at 2 K. The cavities are cooled with superfluid helium filled into their individual helium jackets. This reduces the liquid helium consumption by more than 70% in comparison with the conventional facilities operational elsewhere. The facility has now completed commissioning successfully and moved into a 2-year program to qualify 84 high-beta SRF cavities for the ESS (European Spallation Source) as part of the UK’s in-kind contribution. This paper reports on the commissioning program, along with a detailed discussion of the cryogenic operations and performance of the facility, including that of the cryoplant.

Characterization of NbTi Busbar for HL-LHC Interaction Region Quadrupoles

The US Accelerator Upgrade for the HiLumi-LHC (US-HL-LHC AUP) project and CERN are designing and fabricating superconducting quadrupole magnets for the interaction regions of the High Luminosity Large Hadron Collider (HL-LHC). The triplet is made of three optical elements: Q1, Q2, and Q3. The Nb3Sn quadrupole magnets operate in superfluid He at 1.9 K with a nominal field gradient of 132.6 T/m. The three inner triplet elements are connected together with superconducting buses. The design and fabrication of the through and local buses is carried out at Applied Physics and Superconducting Technology Division (APS-TD) at Fermilab (FNAL). This paper reports the characterization of the bus-bar thermo-electric properties. The bus was tested with a short Nb3Sn magnet (MQXFS1e) in the vertical test facility of the APS-TD at FNAL. The test demonstrated that the bus design is adequate since no spontaneous quench took place up to 17.89 kA current value. Quench propagation velocities were investigated over a range of currents that is typical for accelerator superconducting magnets. Temperature margins were found above that required for the Hi-Lumi triplet bus. The design guarantees the protection of the bus at operational current value according to the quench detection voltage threshold (100 mV) established for the Hi-Lumi LHC interaction region.

2 K superfluid helium cryogenic vertical test system for superconducting cavity of ADS Injector I

The accelerator-driven subcritical system (ADS) is the internationally recognized key technology of nuclear waste problem treatment, of which superconducting proton linac is an important part. With the support of the strategic science and technology pilot project of the Chinese Academy of Sciences, the Institute of High Energy Physics of the Chinese Academy of Sciences took the lead in the research of 325 MHz superconducting proton linac, which is called ADS Injector I. The superconducting accelerator part of ADS Injector I mainly consists of 14 spoke-type superconducting cavities with β 0.12. At the same time, the research work of various cavities with different β values and different frequencies is also carried out to lay the technical and technological foundation for ADS main accelerator. The only way to determine whether the superconducting cavity can reach the design target and whether it can be installed into the cryostat is the vertical test at cryogenic. As the only way to test the microwave performance of the superconducting cavity at low temperature, the vertical test can accurately test the acceleration gradient Eacc and the corresponding quality factor Q0 of the superconducting cavity. The design and construction of the superconducting cavity vertical test facility is based on the practical needs of the pilot project and the long-term development of the superconducting accelerator. This paper mainly introduces the design and construction of the cryogenic vertical test system for the superconducting cavity of ADS Injector I, including the system scheme design, process design, heat load analysis, 2 K superfluid helium obtaining method, system commissioning and operation, etc. The static heat leakage at 2 K of the 2 K superfluid helium vertical test system of ADS Injector I is 1.624 W, which has reached the international advanced level. The 2 K superfluid helium vertical test system of ADS Injector I after constructed not only meets the test requirements of ADS pilot project, but also conducts 4 K and 2 K vertical tests for other different types of superconducting cavities and relevant cryogenic experiments.

Cryogenic safety considerations for Vertical Test Facility for qualifying high-β SRF cavities for the European Spallation Source

A dedicated cryogenic infrastructure has been installed at STFC Daresbury Laboratory to qualify and deliver 84 high-,0 SRF cavities for the ESS (European Spallation Source) under construction in Lund, Sweden. In order to meet the delivery schedule and optimise the test process efficiently, a large 1.6 m diameter, 3.5 m tall liquid helium cryostat has been developed. RF tests are conducted on 3 cavities at 2 K in one cool-down. There are 3 cryogenic circuits operating at 50 K, 4.2 K and 2 K designed to handle a maximum helium mass flow rates of 4 g/s. Considering the large internal beam pipe and external surface areas of the cavities under test, the pressure relief system has been designed very carefully. Various limiting scenarios and associated safety schemes are presented in detail in this paper.

Upgrade of the CERN Superconducting Magnet Test Facility

The superconducting magnet test facility at CERN has hosted the series test of the majority of the LHC magnets. The facility has evolved, and is presently divided in two main areas: a vertical test facility, equipped with three vertical cryostats, and a horizontal test facility, with ten feedboxes for test of cryostated magnets in horizontal position. The test demands from construction projects, such as the high-luminosity LHC, or design studies, such as the future circular collider, are calling for a further upgrade. The new accelerator magnet technology based on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn and HTS superconductors, and the demand for higher bore field, result in high current (up to 30 kA), large cold mass dimensions (up to 1 m diameter), and increased stored energy (up to 1.5 MJ/m). To meet the new demands, two new vertical cryostats with their associated ancillary equipment are being built, and one horizontal test stand is being upgraded for operation at higher current. In addition, an upgrade of the cryogenic plant and services is planned to absorb the additional test needs. The paper gives the input parameters for the upgrade of the magnet test stations and the main characteristics of the new equipment.

Fabrication and testing of 2K cryostat for vertical test facility at RRCAT

Raja Ramanna Centre for Advanced Technology (RRCAT) has developed a 2K Cryostat for characterization of Superconducting RF (SRF) cavities, under Indian Institution Fermilab Collaboration (IIFC). A vertical Test Stand (VTS) is a facility for qualifying bare SRF cavities for their required performance by measuring quality factor and cavity accelerating gradient at a cryogenic temperature of 2K. The VTS cryostat has been designed for a large testing aperture for testing variety of SRF cavities including 325 MHz Spoke resonators, 650 MHz and 1.3 GHz multi-cell SRF cavities. The engineering design and analysis of VTS cryostat has been carried out using ASME B&PV Code and Finite Element Analysis. Fabrication of Cryostat was carried out in strict accordance with ASME B&PV code under joint supervision of engineers from RRCAT and Fermilab. The paper describes the fabrication & acceptance testing aspects of the VTS cryostat at the vendor location and at RRCAT.

Experimental studies and CFD calculations for buoyancy driven mixing phenomena

In nuclear reactor safety the mixing of borated and deborated water is a critical issue that needs investigation, assessment and prediction. Such mixing is buoyancy driven and numerical codes must correctly model momentum transfer between fluids of different density. To assess and develop CFD models for buoyancy driven mixing we set up a simple vertical mixing test facility (VeMix) and equipped it with a newly developed planar electrical imaging sensor. This imaging sensor acquires conductivity images of the liquid at the rear channel wall with a speed of 2,500 frames/s. By adding NaCl tracer to the denser fluid we were able to visualize the mixing process in high spatial and temporal detail. Furthermore, an image processing algorithm based on the optical flow concept was implemented and tested which allows the measurement of flow pattern velocities. Selected experiments at different Richardson numbers were run with two components of different density (pure water and glucose–water mixture) simulating borated and deborated water in a light water reactor scenario. These experiments were compared to CFD calculations using standard turbulence models. Good agreement between experimental data and CFD simulations was found.

The Variable Input Coupler for the Fermilab Vertical Cavity Test Facility

A variable input coupler has been designed for the Fermilab vertical cavity test facility (VCTF), a facility for testing bare 1.3 GHz 9-cell superconducting radiofrequency (SRF) cavities at 2 K, to provide some flexibility in the test stand measurements. The variable coupler allows the cavity to be critically coupled for all tests, including all TM010 passband modes, which will simplify or make possible the measurement of those modes with very low end-cell fields, e.g., pi/9 mode. The variable coupler assembly mounts to the standard input coupler port on the cavity, and uses a cryogenic motor submerged in superfluid helium to control the antenna position. The RF and mechanical design and RF test results are described.

Magnetic Shielding for the Fermilab Vertical Cavity Test Facility

A superconducting RF cavity has to be shielded from magnetic fields present during cool down below the critical temperature to avoid freezing in the magnetic flux at localized impurities, thereby degrading the cavity intrinsic quality factor Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The magnetic shielding designed for the Fermilab vertical cavity test facility (VCTF), a facility for CW RF vertical testing of bare ILC 1.3 GHz 9-cell SRF cavities, was recently completed. For the magnetic shielding design, we used two cylindrical layers: a room temperature ldquoouterrdquo shield of Amumetal (80% Ni alloy), and a 2 K ldquoinnerrdquo shield of Cryoperm 10. The magnetic and mechanical design of the magnetic shielding and measurement of the remanent magnetic field inside the shielding are described.

YS-11型機胴体構造の落下衝撃試験（その1）

The Structures and Materials Research Center of the National Aerospace Laboratory of Japan (NAL) and Kawasaki Heavy Industories, Ltd. (KHI) conducted a vertical drop test of a fuselage section cut from a NAMIC YS-11 transport airplane at NAL vertical drop test facility in December 2001. The main objectives of this program were to obtain background data for aircraft cabin safety by drop test of a full-scale fuselage section and to develop computational method for crash simulation. The test article including seats and anthropomorphic test dummies was dropped to a rigid impact surface at a velocity of 6.1 m/s (20 ft/s). The test condition and result were considered to be severe but potentially survivable. A finite element model of this test article was also developed using the explicit nonlinear transient-dynamic analysis code, LS-DYNA3D. An outline of analytical method and comparison of analysis result with drop test data are presented in this paper.