Vertical Magnet Test Facility Research Articles

Cryogenic and safety design of the future high field cable test facility at Fermilab

The HFVMTF (High Field Vertical Magnet Test Facility) is a new experimental facility under development at Fermi National Accelerator Laboratory (FNAL) to test large superconducting magnets (up to 20 tons weight and 1.3 m diameter) in a double bath superfluid helium cryostat (1.9 K and 1.2 bar). Coupled with a superconducting dipole magnet fabricated by Lawrence Berkeley National Laboratory (LBNL), this facility will be able to test future high-temperature superconductor (HTS) cables under a background magnetic field of 15 T for fusion magnets. This paper describes the design of the cryostat and its 1.4-meter diameter lambda plate, as well as the different components for a safe operation of the facility, even during critical events such a magnet quench or a vacuum breaking situation. The project is funded by US DOE Offices of Science, High Energy Physics (HEP), and Fusion Energy Sciences (FES).

Status of the High Field Cable Test Facility at Fermilab

Fermi National Accelerator Laboratory (FNAL) and Lawrence Berkeley National Laboratory (LBNL) are building a new High Field Vertical Magnet Test Facility (HFVMTF) for testing superconducting cables in high magnetic field. The background magnetic field of 15 T in the HFVMTF will be produced by a magnet provided by LBNL. The HFVMTF is jointly funded by the US DOE Offices of Science, High Energy Physics (HEP), and Fusion Energy Sciences (FES), and will serve as a superconducting cable test facility in high magnetic fields and a wide range of temperatures for HEP and FES communities. This facility will also be used to test high-field superconducting magnet models and demonstrators, including hybrid magnets, produced by the US Magnet Development Program (MDP). The paper describes the status of the facility, including construction, cryostat designs, top and lambda plates, and systems for powering, and quench protection and monitoring.

Design of the cryostat for High Field Vertical Magnet Testing Facility at Fermilab

High Field Vertical Magnet Test Facility (HFVMTF) is a joint project between the Office of High Energy Physics (HEP) and the Office of Fusion Energy Sciences (FES). Its construction is currently under way at Fermi National Accelerator Laboratory (Fermilab). As a part of the project a new double bath superfluid helium cryostat has been designed. The cryostat can accommodate magnets with up to 20 tonne weight and 1.3 m diameter. This paper discusses challenges and solutions for cryostat, lambda plate and heat exchanger design, and presents results of performance analysis.

Design and Construction of a High Field Cable Test Facility at Fermilab

Fermi National Accelerator Laboratory, together with Lawrence Berkeley National Laboratory, is building a new High Field Vertical Magnet Test Facility (HFVMTF) to be situated in the Magnet Test Facility at Fermilab. The HFVMTF is jointly funded by the US DOE Offices of Science, High Energy Physics, and Fusion Energy Sciences, and will serve as a superconducting cable test facility for both communities. The background magnetic field for test samples is 15 T and will be produced by a magnet provided by LBNL operating at 1.9 K in superfluid helium. The samples will be placed in the background magnetic field, cooled to between 4.5 K and a user-specified upper limit, and will be powered with a superconducting transformer at up to 100 kA. Additionally, this facility will be used to test high-field superconducting magnet models and demonstrators, including hybrid magnets, produced by the US Magnet Development Program. Currently, the various tasks of the project are at different stages of execution, from conceptual to ready-for-construction designs. This paper describes the parameters and design status of the pit construction, cryostat, heat exchanger, lambda plate, power system, and quench protection and monitoring systems of the facility.

First Field Measurements of the 15 T Nb3Sn Dipole Demonstrator MDPCT1

Within the US Magnet Development Program (MDP), a 15 T Nb3Sn dipole was developed to demonstrate a possible magnet design for a post-LHC proton-proton Collider. The magnet design is based on 60 mm aperture 4-layer shell-type coils, graded between the inner and outer layers to maximize magnet performance. Magnet coils are surrounded by vertically split thick iron laminations, connected by aluminum I-clamps, and a thick stainless-steel skin. The magnet coils were preloaded to achieve 14 T in the first test. The magnet was tested at the Vertical Magnet Test Facility (VMTF) at Fermilab. This paper reports the first results of magnetic measurements of the 15 T Nb3Sn dipole demonstrator, including dipole strength, geometrical harmonics, coil magnetization and iron saturation effects. At the maximum quench current of 9742 A we obtained a dipole strength of 14.13 T.

First operational experience of the upgraded cryogenic infrastructure of the vertical magnet test facility in the SM18 hall, including HFM and cluster D test stations.

As part of the R&D program for HL-LHC, the future upgrade of the Large Hadron Collider (LHC), the vertical magnet test facility in the SM18 cryogenic test hall at CERN has seen significant development. Since the installation of HFM and Cluster D cryogenic test stations in 2017, the facility is comprised of five vertical test cryostats of various sizes operating at either 1.9 K or 4.2 K. It is now possible to test a wide range of superconducting high field magnets with weigh up to 18 tons, maximum stored energy of 10 MJ and powering requirements up to 30 kA. This article describes the first cryogenic operational experiences with these test stations, their cool-down and warm-up characteristics and the heat in-leak measurements of their components. Major upgrades made to the cryogenic infrastructure of the vertical magnet test facility as a whole are also detailed. This includes the adoption of an improved safety strategy to ensure the continued safe operation of the test facility during all operational modes. As well as the incorporation of quench recovery systems on four of the five test stations to reduce the amount of helium lost during testing and the installation helium guards on infrastructure operating at 1.9 K to avoid the ingress of air to cryogenic circuits.

Measurements of Dynamic Effects in FNAL 11-T Nb3Sn Dipole Models

Fermilab, in collaboration with CERN, has developed a double-aperture 11-T Nb3Sn dipole suitable for the high-luminosity LHC upgrade. During 2012–2014, a 2-m-long single-aperture dipole demonstrator and three 1-m-long single-aperture dipole models were fabricated by FNAL and tested at its Vertical Magnet Test Facility. Collared coils from two of the 1-m-long models were then used to assemble the first double-aperture dipole demonstrator. This magnet had extensive testing in 2015–2016, including quench performance, quench protection, and field quality studies. This paper reports the results of measurements of dynamic effects in the single-aperture and double-aperture 11-T Nb 3Sn dipoles and compares them with similar measurements in previous NbTi magnets.

Summary of Test Results of MQXFS1—The First Short Model 150 mm Aperture Nb3Sn Quadrupole for the High-Luminosity LHC Upgrade

The development of Nb3Sn quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC interaction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb3Sn magnets boosting the LHC program of having 10-fold increase in integrated luminosity after the foreseen upgrades. Previously, LARP conducted successful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated a strong performance at Fermilab's vertical magnet test facility reaching the LHC operating limits. This paper reports the latest results from MQXFS1 tests with changed prestress levels. The overall magnet performance, including quench training and memory, ramp rate, and temperature dependence, is also summarized.

Performance of the First Short Model 150-mm-Aperture Nb3Sn Quadrupole MQXFS for the High-Luminosity LHC Upgrade

The U.S. LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the high-luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb 3Sn quadrupoles for the LHC interaction regions. These magnets will replace the present 70-mm-aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity up to 5 × 1034 cm –2s–1 or more. Over the past decade, LARP successfully fabricated and tested short and long models of 90 and 120-mm-aperture Nb3Sn quadrupoles. Recently, the first short model of 150-mm-diameter quadrupole MQXFS was built with coils fabricated both by LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence, as well as protection heater studies.

Magnetic Measurements of the First Nb3Sn Model Quadrupole (MQXFS) for the High-Luminosity LHC

Author(s): DiMarco, J; Ambrosio, G; Chlachidze, G; Ferracin, P; Holik, E; Sabbi, G; Stoynev, S; Strauss, T; Sylvester, C; Tartaglia, M; Todesco, E; Velev, G; Wang, X | Abstract: The U.S. LHC Accelerator Research Program (LARP) and CERN are developing high-gradient Nb3Sn magnets for the high luminosity LHC interaction regions. Magnetic measurements of the first 1.5-m long, 150-mm aperture model quadrupole, MQXFS1, were performed during magnet assembly at LBNL, as well as during cryogenic testing at Fermilab's Vertical Magnet Test Facility. This paper reports on the results of these magnetic characterization measurements, as well as on the performance of new probes developed for the tests.

Field Quality Measurements of LARP <formula formulatype="inline"><tex Notation="TeX">$\hbox{Nb}_{3} \hbox{Sn}$</tex></formula> Magnet HQ02

Large-aperture, high-field, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn quadrupoles are being developed by the U.S. LHC accelerator research program (LARP) for the High luminosity upgrade of the Large Hadron Collider (HiLumi-LHC). The first 1 m long, 120 mm aperture prototype, HQ01, was assembled with various sets of coils and tested at LBNL and CERN. Based on these results, several design modifications have been introduced to improve the performance for HQ02, the latest model. From the field quality perspective, the most relevant improvements are a cored cable for reduction of eddy current effects, and more uniform coil components and fabrication processes. This paper reports on the magnetic measurements of HQ02 during recent testing at the Vertical Magnet Test Facility at Fermilab. Results of baseline measurements performed with a new multilayer circuit board probe are compared with the earlier magnet. An analysis of probe and measurement system performance is also presented.

Field Quality Study of the LARP ${\rm Nb}_{3}{\rm Sn}$ 3.7 m-Long Quadrupole Models of LQ series

After the successful test of the first long Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn quadrupole magnet (LQS01), the US LHC Accelerator Research Program (LARP) has assembled and tested a new 3.7 m-long Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn quadrupole (LQS02). This magnet has four new coils made of the same conductor as LQS01 coils, and it is using the same support structure. LQS02 was tested at the Fermilab Vertical Magnet Test Facility with the main goal to confirm that the long models can achieve field gradient above 200 T/m, LARP target for 90-mm aperture, as well as to measure the field quality. These long models lack some alignment features and it is important to study the field harmonics. Previous field quality measurements of LQS01 showed higher than expected differences between measured and calculated harmonics compared to the short models (TQS) assembled in a similar structure. These differences could be explained by the use of two different impregnation fixtures during coil fabrication. In this paper, we present a comparison of the field quality measurements between LQS01 and LQS02 as well as a comparison with the short TQS models. If the result supports the coil fabrication hypothesis, another LQS assembly with all coils fabricated in the same fixture will be produced for understanding the cause of the discrepancy between short and long models.