Welcome to the 5th SMTF Workshop

• Marta Bajko (cern)

Room: Saal room Oral presentation (10 min) + Q&A (10 min) Introduction to the Workshop

PSI foreword speech

• Stephane Sanfilippo (PSI - Paul Scherrer Institut)

Room: Saal room A very short description of the PSI and related activities Practical details on accommodation and PSI day.

Test and diagnostic: priorities for high field magnets program

• Ezio Todesco (CERN)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The high field magnet program is an R&D activity focused on the construction of 14 T dipole prototypes in Nb3Sn, proving the HTS technology for main accelerator dipoles in the 14-20 T range, and developing the superconducting technology for particle physics. In this talk we will outline few R&D guidelines that concern test and diagnostics. The recent studies and proposal for an FCC-hh operated at 4.5 K, as in the baseline for the SppC, would require the ability to measure the temperature margin in magnets tested at 4.5 K. Another critical aspect is the measurements of hysteresis losses during ramp, that are one of the main bottlenecks for the energy consumption and dimensioning of cryogenic system. Finally, the measurement of the stability of transfer function and low order multipoles during magnet ramping for both HTS and LTS is a fundamental proof of the viability of both technologies for main magnets in accelerators.

Muon Collider Magnet Programme: Test and Measurement Requirements

• Luca Bottura (CERN)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The muon collider requires advanced magnet systems to meet the demands of muon production, acceleration, and storage. The key targets for magnet R&D include achieving field levels up to 20 T in dipoles, quadrupoles and combined function accelerator magnets, up to 40 T in solenoids, and very fast ramping, up to 3 kT/s, in resistive accelerator magnets. R&D presently focuses on integrating high-temperature superconductors (HTS), developing efficient cooling systems, required to manage heat loads from muon production and decay at the level of kW, ensuring radiation resistance at the level of tens of MGy, and developing efficient MJ-scale energy storage and GW-scale power management for the pulsed accelerators. These exceptional challenges will require intense test and measurements with tailored and advanced techniques, from materials, to magnets, to systems. In this presentation we will outline the magnet challenges, the proposed R&D program and the time scale of the development, prototyping and series production towards a muon collider. Based on the proposed R&D and production programme, we have identified some specific challenges for test and measurements that will need dedicated new methods, sensors and infrastructure. Examples are: - Characterization of HTS material performance at cryogenic temperatures and ultra high field (up to 40 T), including in relevant radiation environment; - High current conductor testing with capabilities up to 20 T, currents up to 60 kA and variable temperature in the range of 4.2 to 100 K; - Characterization of magnet performance, quench detection and protection of NI HTS magnets, including at temperatures above liquid helium (e.g. 10 to 20 K); - Measurement of field quality, stability and reproducibility of NI HTS dipoles and quadrupoles, which can rely on the standard methods of harmonic expansion, as well as combined function accelerator magnets and solenoids, for which a non-standard field representation is required. The presentation will provide a first evaluation of the measurement needs and tentative range of operation, useful to guide future developments and investments in test methods and infrastructure.

The INFN Test Facility for Large Magnets and Superconducting Lines

• Antonella Chiuchiolo (Istituto Nazionale di Fisica Nucleare)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The Test Facility for Large Magnets and Superconducting Lines (TFML) in Salerno, Italy, is a state-of-the-art laboratory dedicated to the development and testing of superconducting technologies. Established and operated by the National Institute of Nuclear Physics (INFN) in collaboration with the University of Salerno's Physics Department TFML supports the THOR (Test in Horizontal) program since 2020. This is dedicated to the Site Acceptance Tests (SAT) of quadrupole doublet modules for the SIS100 synchrotron, part of the FAIR facility under construction at GSI in Darmstadt. The existing facility includes a cryogenic plant capable of cooling magnets to 4.5 K using a supercritical helium stream at 3 bar. Since 2022, within the IRIS (Innovative Research Infrastructure on Applied Superconductivity) program, a second building is under construction in Salerno, adjacent to the already existing facility. The new facility will be dedicated to the test of a 130m long superconducting cable based on MgB2, capable to carry up to 40 kA at 25 kV operating at 20 K Helium gas. The unique features and technical specifications of the facility, along with an overview of its current infrastructure, ongoing activities and developments are presented.

Superconducting magnet String Test for the SIS100 accelerator of FAIR

• Patricia Bartolome (GSI)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The SIS100 accelerator, currently under construction in Darmstadt (Germany), con- sists of six arc and straight sections. Each of the six cryogenic arc sections comprises fourteen regularly repeating optical cells (lattice). Each standard cell includes two dipole magnets and two quadrupole units integrated in a quadrupole doublet module. The SIS100 String Test technically represents one standard cell of the arc section of the SIS100, terminated by and End Cap and a Bypass Line as a representation of the end of the arc section. The purpose of the SIS100 String Test is to validate all technical sys- tems such as cryogenics, vacuum, interlock and quench detection and investigate their collective behavior. A wide spectrum of test are performed during cool down, power- ing at operational conditions and warm up. Additionally, the experience gained during the SIS100 String Test will be crucial for the installation, commissioning and operation of the SIS100. The planning, installation process and first experimental results of the String Test will be presented.

CEA test facilities applied to superconducting magnets, cryomodules and physic detectors

• Roser Vallcorba (CEA Saclay)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The STAARQ cryogenic test station is designed to test and characterize magnetically 2 series of quadrupole magnets for the LHC accelerator: 6 MQ magnets running at 13kA for the LHC consolidation project and 2 MQYY magnets running at 6kA for the HiLumi project. The pressurized superfluid bath required to run those magnets in the station at 1.9K and 1.4 bars can accommodate magnets up to 640 mm in diameter, 5.5m in length and 12t in mass. Among its notable characteristics, the station is equipped with a hermetic cold pumping system (up to 3.5g/s) to run the 1.9K heat exchangers. It enables the recycling of the helium exhaust in the LP circuit of the liquefier without additional purification. The full magnetic characterization of the magnets is achieved through a magnetic probe system running inside 2 anticryostats (50mm diameter and 7.35m length) inside the apertures of the magnets. Finally, the cryostat of the station is equipped with prototype hybrid superconducting current leads running liquid nitrogen to cool the resistive/superconductive junction in order to mitigate the heat leaks the liquefier has to deal with. In this presentation, we will present the results of the initial successful commissioning of the station. We successfully tested the prototype hybrid current leads at their maximum rated current. We also fully characterized the cryogenic process and 1.9K cooling system through an additional heating element enabling the demonstration that the station can provide more than double the 1.9K cooling power than required by the future tests of the MQ and MQYY magnets.

Upgrades of the SM18 magnet test infrastructure at CERN

• Franco Mangiarotti (CERN)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The test capabilities of the SM18 vertical magnet test station is growing alongside the more diverse magnets that will be tested there. An overview of the status of the test station will be presented, and the main upgrades will be summarized in this presentation. These include: a new insert with ~3 m long anticryostats for the Cluster D cryostat, a new setup in the HFM cryostat for (cryostated) magnet tests in a helium gas “bath”, the rehabilitation of the Cluster G feedbox for force flow gaseous helium cooled magnets, and a future new insert for the HFM cryostat for magnet tests in forced flow helium gas up to ~3-5 bar, and up to ~50-70 K.

FRESCA and FRESCA2 facilities at CERN

• Jerome Fleiter (CERN)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) FRESCA, the Facility for the reception of Superconducting cables was built in 1995-1998 at CERN to measure the electrical properties of Rutherford superconducting cables. Its main features are: independently cooled superconducting dipole (9.6 T for FRESCA1 and 13 T for FRESCA2), test currents up to 32 kA, temperature between 1.9 and 4.3 K, long measurement length of 60 cm and applied transverse field either perpendicular or parallel to the cable face. Within the outer cryostat containing the magnet, an inner cryostat is installed containing the sample insert. This approach makes it possible to change samples while keeping the background magnet cold, decreasing the helium consumption and cool-down time of the samples. In this presentation the FRESCA test facility and the typical measurements will be discussed.

STRING test facility at CERN for HL-LHC

• Marta Bajko (cern)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The High-Luminosity Large Hadron Collider (HL-LHC) Inner Triplet (IT) STRING aims to faithfully replicate, within a surface building, the collective behavior of various systems in the new HL-LHC IT zone. These systems include superconducting magnets, magnet protection, cryogenics for both the magnets and the superconducting link, powering, vacuum, alignment, magnet interconnections, and the superconducting link itself. The construction of this test bed, designed to be completed years ahead of the actual equipment installation in the LHC tunnel, is now well advanced. Initiated in 2016, the project has taken significant shape: most of the hardware is in place, and parts of the control and software systems are already operational. By the end of 2025, we expect the entire STRING to be cooled to 1.9 K, marking the readiness for the String Validation Program. In this talk, we will provide an update on the installation status, describe the major components, outline the test program, and discuss the next steps.

BNL test facility

• Joshi Piyush (BNL)

Room: Saal room Oral presentation (20 min) + Q&A (10 min)

FNAL test facility

• Vladica Nikolic (FNAL)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) This presentation will focus on the current testing capabilities for superconducting magnets at Fermilab, highlighting existing systems, recent upgrades, and future plans. The Vertical Magnet Test Facility (VMTF) remains a cornerstone for testing superconducting magnets in R&D applications, maintaining its established capabilities. Stand 4 continues to support the Hi-Lumi AUP production line of magnets in cryostats and has achieved significant improvements through a redesign of lead connections, resolving issues with liquid helium levels and resistance, culminating in a successful endurance test without interruption. Similarly, Stand 7 underwent commissioning and a lead redesign to reduce heat load, while its core testing capabilities remain unchanged. Looking forward, Stand 3 is undergoing a redesign, with plans to restart and begin commissioning by the end of 2025, introducing new features such as background magnetic field testing and upgraded power supplies. Fermilab is also advancing the High Field Vertical Magnet Test Facility (HFVMTF), designed to support the fusion and magnet R&D program, with commissioning scheduled for 2025 and critical components, including the cryostat and power supplies, being delivered. Enhancing all operations, the newly commissioned IB1 cryoplant now offers automated overnight helium production and efficient transfer to a 10,000-liter dewar, streamlining support across all test stands. This talk will provide a comprehensive overview of testing capabilities, and showcasing how Fermilab is advancing its capabilities to meet the evolving demands of superconducting magnet testing.

US MD Program - Road Map. Test Infrastructures

• Soren Prestemon (LBNL)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The US Particle Physics community has completed its decadal planning process, culminating in the Particle Physics Project Prioritization Panel (P5) report [1]. Over the last year the US Magnet Development Program has worked to update its its research roadmap to align with the P5 strategy, and in particular is focusing on developing magnet technology that can enable the primary 10TeV Parton Center of Mass colliders such as the FCC-hh and the muon collider. We will provide an overview of of the updated MDP roadmap, and describe progress over the last couple of years in both LTS and HTS accelerator magnet technology in the US. A major thrust of the program in the coming years will be the testing of HTS “inserts” in Nb3Sn “outsert” dipoles, requiring advances and improvements in MDP test facilities to enable independent powering and energy extraction of the HTS and LTS magnets. Advances are also required in our ability to model and diagnose quench initiation and the energy extraction process, and to determine design and test parameters that enable safe operation without degradation to the conductor, and program elements are designed to help address these issues.

Design and progress status of the ITER Magnet Cold Test Bench to test TF and PF1 coils

• Christine Hoa (ITER)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The 19 Toroidal Field (TF) coils, including one spare, have been manufactured by Japan and Europe and have been delivered on ITER site. The Poloidal Field Coil PF1, procured by Russia has also arrived on site. The new baseline schedule has given the Project the opportunity to build a magnet test bench (MCTB) on site in order to test some of the ITER TF coils and the PF1 coil taking into account the new assembly schedule. The most complete magnet integrated tests will be performed to gain experience for the tokamak commissioning. The main objective of the tests is to check the overall magnet performance (joint resistance, mechanical deformation, operating conditions) and confirm the proper operation of the coils. One major risk mitigation is the check of the ground insulation and ground protection. The TF coils will be energized at half nominal current (34 kA) to optimize the testing plan and meet the tokamak assembly schedule. Only the TFC19 spare coil and PF1 will be tested at nominal current, respectively 68 kA and 48 kA. The coils will be cooled with supercritical helium at 4.75 K and 0.46 MPa provided by the ITER cryoplant. Most of the components of the test facility will be ITER relevant and will allow the test of the instrumentation chains and control logics foreseen for the ITER operation. An ITER Cold Terminal Box will be connected to the coil for the helium and electrical supplies. The cryogenic system will provide enough refrigeration capacity with one out of the three ITER refrigeration cold boxes and will supply supercritical helium to the TF winding pack, casing and busbars. One important system to be tested will be the magnet protection system to demonstrate the quench detection capabilities (primary, secondary and safety class detection). A 21 m long- 11 m large and 6 m height cryostat is being manufactured to position horizontally either a TF coil or PF1 coil. A dedicated power supply will energize the coil and a Fast Discharge Unit will protect the coil in case of Fast discharge and quench. The presentation gives an overview of the design of the test facility, the progress status of the main components and the testing program. "The views and opinions expressed herein do not necessarily reflect those of the ITER Organization”

Development of the Magnet System for the Gauss Fusion Stellarator

• Neil Mitchell (Gauss Fusion)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) Gauss Fusion is developing the magnet system for a conventional 4-module QI Stellarator based 1GW electrical plant with realistic and commercially viable component maintenance routes and nuclear life times. Such a choice produces a design so that the magnetic systems do not require very high field strength (up to about 13 T). However, they have complex shaping and support requirements, and need to be developed to better match the requirements of the nuclear systems, as regards access for maintenance, repairability, reliability and efficient structural design while exploiting the advantages of a steady state stellarator configuration. Gauss Fusion will summarise the major parameters of the stellarator and the associated conceptual design of the magnet system, and the ongoing technical activities in the areas of coil structures, demountable coils, and quench protection leading to verification by a model coil programme and test platform requirements.

Challenges of test infrastructures for fusion in the US ( MIT, CFS)

• Theodore Golfinopoulos (Massachusetts Institute of Technology)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The Superconducting Magnet Test Facility (SMTF) at MIT's Plasma Science and Fusion Center provides a range of capabilities to support development of HTS magnet technology. Constructed between 2019-2021 around the SPARC Toroidal Field Model Coil (TFMC) – a non-insulated HTS magnet – it has subsequently been upgraded and employed to service a broader range of test objectives, including those of insulated magnet systems. The main facility provides a large cryostat with power supply and binary HTS current leads capable of continuous operation at 50 kA. Cooling is provided by a closed-loop supercritical helium cryogenic infrastructure that provides ~600 W of cooling at 20 K. The facility also provides a large amount of instrumentation for data acquisition and control. The SMTF has been used to test the SPARC toroidal and central solenoid model coils, as well as a smaller forerunner to the CSMC, and will host the "Magnet 0" test coil of Type One Energy in 2025. In support of these later experiments, a quench detection and fast discharge system has been deployed, with response times on the order of 100 ms. Presently, discharges are limited to 125 V, with further hardening of the system desired to increase this ceiling. Moreover, proposals have been prepared to install a set of pulsed power supplies at 800 V and 16 kA, together with new current leads and other ancillary systems. A satellite facility services testing in liquid nitrogen. A 16 kA, 10 V power supply is available for testing a wide variety of coils, cables, and other samples. Several liquid nitrogen cryostats host these samples, and custom cryostats may be built for form factors that exceed the parameters handled by these, while direct connection to a 26000-liter (7000 gallon) LN2 tank provides for substantial volumes of liquid nitrogen for long-duration, large-scale tests. Desired upgrades to this facility include an expansion of the instrumentation and control system, the addition of a small cryostat and helium circulation loop for test articles of a scale not appropriate to the larger facility, and a further increase in available voltage and fast discharge capabilities.

ITER CS Magnet Module Test Facility Status Report

• Kenneth Khumthong (General Atomics)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) General Atomics (GA) is under contract by US ITER organization (UT-Battelle c/o Oak Ridge National Laboratory) for the fabrication of ITER Central Solenoid (CS) Magnet Modules. GA will provide seven modules to ITER Organization (IO), six of which will be assembled in a stack that forms the ITER Central Solenoid. All CS Modules are required to pass factory acceptance testing (FAT) at General Atomics’ Magnet Technology Center (MTC) test facility prior to shipment to IO. Currently, CS Modules 1, 2, 4, and 5 have completed FAT and have been delivered to IO. CS Module 7 has completed FAT and is being prepared for shipment to IO. CS Module 6 has completed the FAT powered testing portion and CS Module 3 will repeat FAT after repairs are completed on the Module. The MTC test facility was designed and built to conduct factory acceptance tests on low-temperature superconducting magnets for fusion research, i.e. CS Modules. The test facility consists of the test chamber, high vacuum system, 4.5 K recirculating supercritical helium refrigeration plant, 50 kA direct current power supply, counter-pulsed direct current circuit breakers, 1 GJ discharge resistor, high- temperature superconducting current feeders, data acquisition system, supervisory control logic, and magnet quench protection system. Each CS Module FAT campaign comprises of a pre-cooldown 30 kV electrical insulation test at ambient pressure, pre-cooldown 15 kV electrical insulation tests at sub-atmospheric (Paschen) pressures, pre- cooldown 30 bara global helium leak test, controlled cooldown to 4.5 K, hydraulic impedance tests at 4.5 K, AC loss measurements (6.8 and 23.4 second decay time constants) at currents up to 40 kA, current cycling from 0.5 kA to 40 kA, coil height displacement and surface strain measurements, cold (<20 K) 30 bara global helium leak test, controlled warmup to room temperature, post-cooldown 30 kV electrical insulation test at ambient pressure, and post-cooldown 15 kV Paschen tests. Additionally, temperature- current sharing tests up to 8 K were performed on CS Module 6 and are planned for CS Module 3. A summary of the test facility equipment and operational lessons, upgrades, and modifications developed and implemented from tests performed on CS Modules 1-7 (thus far) will be discussed. This work was supported by UT-Battelle/Oak Ridge National Laboratory under sponsorship of the US Department of Energy Office of Science under Awards 4000103039 and DE-AC05-00OR22725.

Status update from the FREIA Laboratory

• Rocio Santiago Kern (Uppsala University)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) The FREIA Laboratory, which is part of the Department of Physics and Astronomy at Uppsala University in Sweden, is a research facility that focuses on R&D on superconducting accelerator technology. As part of the lab, there is the vertical cryostat Gersemi with an associated test-stand for superconducting magnets. We are currently upgrading the test-stand by adding a system for magnetic field measurements. It is based on rotating coils and an anticryostat, in order to keep the sensor warm while operating the magnet at cryogenic temperatures. We will report on the latest updates of the lab, our magnet development activities, and the plans ahead.

GSI Test facility at CERN

• Hugo Bajas (GSI)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) As part of the FAIR project and within the GSI and CERN collaboration, the superferric magnet production series —key components of the Superconducting FRagment Separator (SuperFRS) under construction at GSI Darmstadt, Germany— are undergoing rigorous testing at CERN in a dedicated cryogenics test facility. The tested magnets include dipoles and various types of multiplets (composed of different numbers of quadrupoles, steering dipoles, sextupoles, and octupoles, housed inside a shared vacuum vessel), which must be qualified for cryogenics, electrical and magnetic field performances. For this workshop, we will present the actual status of the cryogenics facility that is composed of three test benches. Each bench can be connected up to nine power converters for the purpose of multiplet testing. The cryogenics, the quench detection and the energy extraction systems will be shown. The status of the SuperFRS magnet testing will then be exposed along with the main results obtained so far. A quick discussion around magnet training will be launched. At last, the future of the test facility will be presented in terms of possible improvements and upcoming upgrades.

LASA test facility

• Marco Statera (INFN - LASA)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) LASA laboratory at INFN Milano unit have been testing superconducting magnets and conductors at 4.5 K for several projects, including ATLAS, DISCORAP (SIS300) and HL-LHC high order correctors by three test stations. An update of those test stations is ongoing in the framework of the next generation EU project IRIS (Innovative Research Infrastructure on applied Superconductivity). The updated tests area will provide three variable temperature conduction-cooled test beds, one system also provides a background field up to 8 T. The powering and protection systems are updated up to 30 kA with a fast switch. A detailed description of testing capabilities and the schedule of the update are presented.

A test facility for cryocooler-based superconducting magnets and advanced cryogenics

• Quentin Gorit (PSI - Paul Scherrer Institut)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) A test facility has been developed at the Paul Scherrer Institut to test cryocooler-based LTS and HTS magnets and develop novel cryogenic devices for their cooling. This contribution describes the experimental set-up, different tests of insulated and non-insulated HTS magnets and shows the results of the, to our knowledge, first ever cooldown and operation of an HTS coil using neon pulsating heat pipes as thermal bus with a cryocooler.

Latest progresses of cold test facilities development for fusion SC magnet technology at ASIPP

• Fang Liu (Chinese Academy of Sciences)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) Supported by the national project CRAFT, which aims to explore and master fusion DEMO level key technologies and establish testing facilities for key material, components and system for CFETR, serials cold test facility for SC material, conductor and magnet are under construction and planned to be completed this year. The SC material testing facility has already been accomplished, mainly consists of a self-developed superconducting background magnets with field of 19T and aperture of 70mm, and multifunctional sample holders. The conductor test facility (Super-X), aims to evaluate the reliability of engineering technology and safe operation for CICC in operation environment, mainly consists of a 15T split solenoid background DC magnet, a 100kA superconducting transformer, and auxiliary system. For the fusion magnet testing, two large-scale facilities will be used. The one with dimension of φ7.7m*H11m, current capacity of 60kA and refrigerator of 1000W@4.5K, has already been used for the CFETR CSMC coil test in 2024. The current of CSMC reached to the design parameter 48kA. The other with dimension of 25m×15.5m×10m has two pairs of current leads with capacity of 100 kA and 60 kA respectively, will be used for CFETR TF and BEST TF magnets tests. Up to 4 BEST TF magnets can be tested at once using this facility.

Cryogenic developments for very high field magnets

• Bertrand Baudouy (CEA Saclay)

Room: Saal room Oral presentation (20 min) + Q&A (10 min) Very high permanent magnetic fields, i.e., over 20 T, are produced by superconducting magnets made partially, or fully, with high-temperature superconducting (HTS) conductors. These specific magnets generally operate at liquid helium temperatures to take full advantage of the HTS properties. Very high-field magnets, usually immersed in a saturated liquid helium bath, experience an excessive temperature increase in working conditions above 20 T. Beyond this threshold, it has been demonstrated that the magnetic force is strong enough to interact with helium molecules due to their diamagnetism. The magnetic field distribution can cause this body force to compensate for gravity, creating zones of levitation around the magnet. It either degrades the boiling heat transfer, preventing bubbles from developing freely and leaving the magnet surface, or traps helium vapor structures on the magnet surface, thus creating a film at the liquid and the magnet interface. To avoid jeopardizing the long-term operation of superconducting high-field magnets cooled by liquid helium at 4.2 K beyond 20 T, heat transfer in liquid helium under these conditions must be fully understood and quantified. An alternative solution is to use a non-gravity-assisted cooling system, such as a capillary heat pipe. This talk presents the recent experimental studies carried out at CEA Paris-Saclay on the helium pool boiling heat transfer under reduced gravity and the development of gravity-independent heat pipes for cooling a 10T class HTS magnet.

Lectures on Superconducting Magnet Test Stands, Magnet Protections and Diagnostics

• Hugo Bajas (GSI)

Room: Saal room Oral presentation (15 min) + Q&A (5 min) Presentation of the updated online lectures on superconducting magnet test stands, protection, and diagnostics, scheduled for June 3rd–13th, 2025.

Close Out

• marta bajko (cern)

Room: Saal room

JORDI test facility (SPC, EPFL)

• Nikolay Bykovskiy (PSI - Paul Scherrer Institut)

Oral presentation (25 min) + Q&A (10 min) An extensive characterization of cable-in-conduit conductors (CICC) at the EPFL Swiss Plasma Center led to the construction of the JORDI test stand in the 2000s, initially used for JOint Resistance DIstribution measurements in CICC immersed in a liquid helium bath [1]. The test stand is connected to a cryoplant supplying helium in a supercritical state at ~10 bar pressure and ~4.5 K temperature, as well as a DC power supply rated for 10 kA and 2 V. Consequently, it was used for testing sub-scale HTS current leads designed for fusion magnets; however the helium flow was still expanded to relatively low pressures, close to 1 bar [2]. Currently, we aim to upgrade JORDI in terms of cooling conditions, operating currents, and background magnetic fields to expand the testing capabilities at SPC within a testing zone of 0.7 m in diameter and 1 m in length. The latest developments, including a list of components required for the upgrade (e.g., mass-flow orifice, superconducting transformer, background field coils, etc.), as well as the first test samples, such as superconducting switches and HTS coil windings, will be discussed in this work.

EDIPO test facility

• Xabier Sarasola (EPFL - SPC)

Oral presentation (25 min) + Q&A (10 min) The EDIPO 2 test facility will complement and enhance SULTAN at EPFL-SPC, which has qualified superconductors for all major superconducting fusion facilities worldwide over the past two decades. EDIPO2 will significantly enhance the high-current and high-field testing capabilities at EPFL-SPC to align with the requirements of the new generation of superconducting samples, driven by the development of High Temperature Superconductors. The background field of EDIPO 2 will reach 15 T (compared to 10.9 T in SULTAN) in the center of a square aperture of 144×144 mm² (94×144 mm² in SULTAN) and its superconducting transformer is designed for testing samples beyond 100 kA. In recent years, EPFL-SPC has developed the conceptual design for the EDIPO2 magnet which relies only on planar racetrack coils wound with a flat two-stage cable. This presentation will provide an overview of the EDIPO 2 design and the latest progress, including the procurement of the Nb₃Sn strand, the production of prototype copper dummy and Nb₃Sn cables, and the initiation of technological R&D and engineering design for coil manufacturing.

Women in Science

• Christine Hoa (ITER)
• Marta Bajko (cern)
• Antonella Chiuchiolo (Istituto Nazionale di Fisica Nucleare)
• Rocio Santiago Kern
• Franco Mangiarotti (CERN)
• Patricia Bartolome (GSI)
• Roser Vallcorba (CEA Saclay)
• Carolin Zoller (PSI - Paul Scherrer Institut)

Join us for a free exchange regarding the Women in Science and Technology on the 2nd of April 2025 at PSI. Are you passionate about the future of science and technology? Don’t miss this engaging discussion on the role of women in superconductivity and cryogenic measurements! • Meet female scientists who are pioneering in superconductivity and cryogenic research. • Connect with professionals and enthusiasts who share your passion for science and innovation. • Discuss how we can foster a more inclusive and supportive environment for the next generation of scientists. The participation of female scientists in the SMTF workshop is steadily increasing, as reflected in the growing number of talks given by women. But how can we sustain and further this positive trend? Key questions we'll explore: • How can we continue to inspire and support young women in the field? • What motivated us to join this field, and would those same factors appeal to the next generation? • How do our male colleagues view the impact of diversity? • What unique perspectives and strengths do female scientists bring to research teams, collaboration, and scientific progress? Join us for a session of inspiration and insight. Together, we can shape the future of superconductivity and technology by fostering an inclusive and diverse scientific community.

Sponsor's presentation

Introduction and Welcome PSI

• Hans-Heinrich Braun (PSI - Paul Scherrer Institut)

Introduction and Welcome EPFL/SPC

• Kamil Sedlak (PSI - Paul Scherrer Institut)

Welcome/IDSM program overview

• Gerard WILLERING (CERN)
• Maxim Marchevsky (Lawrence Berkeley National Laboratory)

Room: Saal room

Challenges in Instrumentation and Diagnostics for Nb3Sn magnets

• Gerard WILLERING (CERN)

Room: Saal room In the past 15 years accelerator magnet development focused on Nb3Sn magnet technology, reaching a mature state for 11T dipole magnets and MQXF quadruple magnets built at CERN and in the US LARP and AUP programs. Instrumentation and diagnostics methods reached maturity with state of art Quench Antenna, rotating coil magnetic measurements, high precision voltage measurement on full coils, strain measurements, fiber optics, etc. Quench localization methods have been improved strongly in Cosθ magnets using the harmonic quench antenna in the bore of the magnet. With a coil length of up to 7 meter long and reduced instrumentation when the magnets are in operation in the HL-LHC, it is important to be able to do diagnostics on only the few voltage signals that can be retrieved. Through the past years, the HFM program has been launched and many model magnets use block coil technology, either in racetrack configuration or with flared ends. With the existing technology it has been very difficult to identify the location of a quench with high enough precision, since quench antenna seem less sensitive to quenches in the coil block and can sometimes not be deployed due to absence of a bore. Repetitive flattop quenches were found in some magnets and it proves difficult to describe its exact origin and the diagnostics methods will be discussed. In this presentation examples of recent challenges in Nb3Sn magnet diagnostics will be discussed, including a discussion on possible instrumentation and diagnostics solutions. This presentation is intended to start a fruitful workshop discussion.

Challenges in Instrumentation and Diagnostics in the Hybrid Magnet Program

• Soren Prestemon (LBNL)

Room: Saal room Instrumentation and diagnostics are crucial for gaining direct insights into magnet performance, making them essential for both magnet operation and guiding magnet development. This is particularly true when they are combined with modeling and analysis, which together demonstrate a comprehensive scientific understanding of magnet performance. The US Magnet Development Program (MDP) is actively pursuing high-temperature superconducting (HTS) accelerator magnet technology to enable new high-field regimes. In the coming years, we aim to develop, build, and test a series of hybrid accelerator magnets. These will utilize large-bore Nb3Sn-based “outsert” dipoles and HTS (REBCO and Bi2212) “insert” dipoles, each equipped with independent powering and energy extraction systems. We foresee a critical need for advanced instrumentation that can serve as the foundation for HTS magnet protection. Ideally, this instrumentation would identify quench precursors and/or deviations from standard operational parameters, allowing sufficient time to extract energy and/or transition the system into a safe, controlled operational mode. The high-field solenoid community has extensive experience in designing, testing, and operating hybrid low-temperature superconducting (LTS)/HTS systems. The renewed interest from the high-energy physics community in a muon collider as a potential energy frontier facility is acting as a catalyst for the MDP to strengthen its collaborations with the solenoid community, thereby leveraging and building on their expertise.

Challenges in Instrumentation and Diagnostics in HTS magnets

• Maxim Marchevsky (Lawrence Berkeley National Laboratory)
• - Guided discussion
• Gerard WILLERING (CERN)

Room: Saal room

HTS quench detection using optical fibers, co-wound wires and thermocouple arrays

• Nikolay Bykovskiy (PSI - Paul Scherrer Institut)

Room: Saal room Three quench detection methods are being developed at SPC: (1) resistance measurements of superconducting quench detection (SQD) wires, (2) voltage measurements across series-connected thermocouple wires, and (3) measurements of the spectral shift of light reflected by FBG optical fibers. All three methods primarily respond to temperature rise and are designed to be immune to electromagnetic noise (a challenge for (1) and (2)) and mechanical strain (a challenge for (3)). Here, we will emphasize the specifics of the developed methods, focusing in particular on their integration. Corresponding experimental demonstrations have been carried out in SULTAN on LTS and HTS high-current insert coils, using an identical instrumentation plate that contained approximately ~10 m long detection instruments of each type. We will highlight the key findings from these experiments and outline the next steps in the development, aimed at creating a co-wound instrumentation strip that can be used simultaneously for quench detection, mechanical reinforcement, and turn insulation.

RF quench detection in HTS magnets

• Maxim Marchevsky (Lawrence Berkeley National Laboratory)

Room: Saal room Detection of the thermal runaway and its precursors is critical for HTS high-field magnets in High Energy Physics and Fusion applications. Among various distributed sensing techniques, radio-frequency (RF)-based methodology emerges as a versatile method combining the best features of other sensing technologies, such as fiber-optic and ultrasonic sensing, while offering unique capabilities such as self-calibration and distributed calorimetry. RF sensors are robust, flexible, and can be bent over a small radius of curvature without affecting performance and operated in a wide temperature range from ambient to 4 K. I will review the principles of this technique and provide an overview of the latest LBNL developments in RF sensing technology. Tests at 77 K and 4 K involving RF sensors integrated with various HTS cable conductors will be presented, and prospects of using these techniques to monitor large-scale magnets will be discussed.

Updates on Fiberoptic Sensing at FNAL

• Steve Krave (FNAL)

Room: Saal room Fermilab has been exploring the use of distributed strain and temperature sensing fibers on superconducting magnets. This presentation provides updates on the technology including application to quench propagation in short samples, measurements on coils during assembly, and the many challenges of the subject from splicing to signal loss and calibration shift.

Advanced DAQ and Quench Detection using FPGA based UQDS systems

• Jens Steckert (CERN)

Room: Saal room

Use of UQDS for various HTS coils

• Michal Duda (PSI - Paul Scherrer Institut)

Room: Saal room

Cryogenic Tests of Electronic Components and Sensors for Superconducting Magnet Instrumentation

• Vincenzo Di Capua (CERN)

Room: Saal room This research explores the development of advanced electronic systems for magnetic measurements under various operating conditions. The study focuses on two main areas: Characterization of electronic components and sensors in extreme temperature environments, from cryogenic to room temperature. Development of electronics for standard magnetic measurements and quench localization techniques at room temperature. The aim is to identify and optimize suitable components for advanced instrumentation in the field of magnetic measurements, with particular attention to the performance of amplifiers, passive elements, digital components, and various types of sensors. Experimental results show how some components maintain functionality across a wide temperature range while others require specific adaptations. In parallel, innovative solutions for precise magnetic measurements and early quench detection techniques at room temperature are presented. This research contributes to the advancement of electronic systems for magnetic measurements in various applications, from superconductor technologies to high-energy physics, medical imaging, and advanced materials science.

Magnetic Field Measurements of the Super-FRS magnets

• Pawel Kosek (GSI)

Room: Saal room The Super-FRS (Superconducting FRagment Separator) is part of the new superconducting accelerator complex (FAIR) [1], which is under construction at the Helmholtz Center for Heavy Ion Research (GSI) in Darmstadt, Germany. The Super-FRS is composed of 24 superferric dipole magnets and 31 multiplet assemblies, with up to nine magnets in a common cryostat (175 quadruple and corrector magnets in total). The acceptance tests are currently taking place at CERN in a dedicated cryogenic test facility [2]. To date, two dipole magnets and 13 multiplets have been tested. This talk will highlight the magnetic measurements testing program. Instruments for the magnetic measurements include, for the multiplets, a 334 mm diameter rotating-coil magnetometer and a single stretched wire system [3]. For the dipole magnets, we use an array of induction coils translating longitudinally through the aperture (i.e., a translating fluxmeter [4]), a single stretched wire, and the 3D mapper. The presentation will compare the applied measurement techniques addressing their respective advantages and limitations. The talk will outline the measurement results, present the metrological performance of the instruments, and describe the data analysis techniques. The results will include the magnetic axis, field strength and field quality, as well as the crosstalk effect between adjacent magnets. The measurement results will be compared to simulation and the sources of the differences will be discussed. The presentation will conclude with the challenges encountered and lessons learned during the initial part of the measurement campaign.

Status of work on a Non-rotating Magnetic Field Harmonics Probe

• joe dimarco (Fermi National Accelerator Laboratory)

Room: Saal room Being able to accurately measure magnetic field harmonics with a stationary probe can be advantageous. The typical mechanics required to rotate the probe and maintain alignment are obviated, as even could be the anti-cryostat for a superconducting magnet test, for example. This talk describes work towards one such device which uses a piezo sensor to detect torque caused by AC power applied in turn to vertices around the perimeter of a cylindrical coil. The voltage measured from the sensor is proportional to the force at a given vertex, and thus to the field, allowing determination of field harmonics from the ensemble. A proof of concept coil is described and a first look at data acquired is presented.

TITO: Individual Tape Powering Experiments in CORC® High Temperature Superconducting Cables

• Reed Teyber

Room: Saal room ReBCO high temperature superconducting cables have the potential to push the performance limits of fusion and high energy physics magnets. One of the ongoing development challenges with this research is conductor stability, caused by local performance reductions in individual tapes from tape manufacturing, magnet manufacturing and magnet operation. The resulting current redistribution around these defects can induce a magnet quench and irreversible performance degradation. In this work, we present our progress on individual tape powering experiments in CORC® high temperature superconducting cables to probe this phenomenon. Developments in the cable termination, electrical controls for automated tape switching and a simplified model for current percolation in CORC® cables are presented. Analyzed measurements are shown with a straight cable and with a bent cable at radii of 152 mm and 76 mm. The Lawrencium computing cluster is then used to attempt to fit model parameters to these experiments. The methods and results provide both quantitative insight and help derive deeper understanding of the current sharing and current distributions in High Temperature Superconducting cables.

Quench Antennasfor Accelerator Magnets

• Lucio Fiscarelli (CERN)

Room: Saal room The positive experience with quench antennas used for the HL-LHC magnets fosters new developments for other projects. In its first phase, the HFM program includes the construction and testing of demonstrator magnets based on racetrack coils. Racetrack coils do not have, or do not provide access to, a round aperture. Therefore, cylindrical quench antennas cannot be used. Instead, search coils can be positioned on the flat surfaces around the magnet coils. With such setup, the quench position can be as well estimated from a relatively small number of useful signals. A suitable sensor design, together with the use of compensated signals, allows the reconstruction with a precision better than 5 mm.

Building Training Datasets and Semi-Supervised Models for Magnet Quench Detection

• Maira Khan (FNAL)

Room: Saal room Detecting quenches in superconducting (SC) magnets during training is a challenging process that involves capturing physical events that occur at different frequencies and appear as various signal features. These events may be correlated across instrumentation type,thermal cycle, and ramp. These events together build a more complete picture of continuous processes occurring in the magnet, and may allow us to flag potential precursors for quench detection. We build upon our existing work on unsupervised autoencoders for acoustic sensors and quench antenna (QA) by first establishing a supervised ML training pipeline. We show the results of an event tagging, analysis, and simulation framework which are used concurrently to build a training dataset for a supervised implementation. We then show how this supervised training can be used as a prior in a semi-supervised framework and compare this to the unsupervised auto-encoder performance. This allows us to have a more concrete understanding of the performance of our algorithms relative to physical events occurring in the magnet, and also provides a baseline software tool to generically evaluate autoencoders under completely unsupervised, supervised, and semi-supervised training conditions.

Novel method for quench initiation using ESC

• Emmanuele Ravaioli (CERN)

Room: Saal room

Advances in Superconducting Magnet Monitoring via in-situ fiber optic sensing techniques including effects of ionizing radiation.

• Federico Scurti (NCSU)

Room: Saal room Superconducting magnets play a critical role in a wide range of applications, including their use as an enabling technology for fusion energy. However, ensuring their reliable operation requires robust monitoring techniques to prevent catastrophic magnet failure. Fiber optic sensors have emerged as a promising solution to address this technical gap, offering distributed, online strain and temperature measurements. Prior research has demonstrated that optical fibers can be successfully integrated into superconducting magnets, though further optimization is needed to maximize their performance and reliability. This contribution presents recent progress at Penn State and collaborating institutions in the development of fiber optic sensing techniques for in-situ health monitoring of superconducting magnets. The work includes advancements in Rayleigh scattering-based Optical Frequency Domain Reflectometry (OFDR), particularly improvements in sensing length, measurement rate, and characterization of its response to vibrations and AC current operation. Additionally, new developments in Brillouin scattering-based Optical Time Domain Reflectometry (B-OTDR) for cryogenic applications are highlighted, with a focus on performance below 40 K. Results of a novel technique based on coherent-phase Optical Time Domain Reflectometry (cp-OTDR) are also presented, including its potential and current limitations in cryogenic environments. Further, we present the cryogenic characterization of a novel type of Fiber Bragg Grating (FBG) that can be inscribed in a wide range of optical fiber material compositions, enabling higher radiation tolerance for fusion reactor environments. The effects of ionizing radiation on these sensing techniques are also investigated, since the optical fibers are to be integrated into systems exposed to ionizing radiation, such as particle accelerators and fusion reactors. Optical fibers Emphasis is placed on understanding how cryogenic irradiation influences sensor performance compared to room-temperature irradiation. Finally, we explore new concepts for integrating optical fibers into pancake coil configurations, including both insulated and non-insulated coil designs. These advancements mark a step forward toward the deployment of fiber optic sensors as a tool for preventing failure of superconducting magnets operated in complex environments.

Electromagnetic Transients during SMCT01b Testing

• Steven Krave (FNAL)

Room: Saal room Following work presented at the last IDSM workshop, FNAL had a unique opportunity to measure electromagnetic transients during magnet testing with SMCT01b. This magnet exhibited an unusual training behavior where a large voltage spike appeared shortly before a quench was initiated. To identify the source of the spike, an additional current transducer was added to the magnet test to search for transient behavior during ramping. The measurement suggests substantial coil motion, consistent with mechanical analysis and observations of electromagnetic noise. This measurement suggests a reasonable physical displacement in line with predicted values.

Quench detection using cryogenic electronics

• Joshi Piyush (BNL)

Room: Saal room

Close-out session - workshop feedback

• marta bajko (cern)

Room: Saal room