In this paper we give a first baseline of the interaction region. We discuss the main motivations that lead us to choose the technology, the combination of fields/gradients and lengths, the apertures, the quantity of superconductor, and the operational margin. Key elements are also the constraints given by the energy deposition in terms of heat load and radiation damage; we present the main features related to shielding and heat removal.

The iron-based superconductor (IBS) single pancake coil (SPC) with 30 mm inner diameter was firstly fabricated and tested under 24 T background field. This SPC was successfully made using the 7-filamentary Ba1-xKxFe2As2 (Ba122) tape by wind-andreact method. This IBS coil show the highest Ic value at magnetic field reported so far.For example, the transport critical current of this Ba122 SPC achieved 35 A at 4.2 K and 10 T, which is about half of that of short sample. This indicates that the noninsulation winding process together with the stainless-steel tape is suitable to the ironbased superconductor. Even more encouraging is the fact that the Ic of this SPC is still as high as 26 A under 24 T background field, which is still about 40% of that at zero external magnetic field. These results clearly demonstrate that the iron-based superconductors are very promising for high-field magnet applications.

Iron-based superconducting (IBS) racetrack coils were firstly fabricated by using 100-m 7-filamentary Ba1-xKxFe2As2 (Ba122) tapes at the Institute of High Energy Physics, Chinese Academy of Sciences (IHEP, CAS). The IBS tape was wound in parallel with stainless steel tape to withstand the high tensile hoop stress under high magnetic field. After the heat treatment, the coils were impregnated with epoxy resin. Then the IBS coils were tested in a low-temperature superconducting Common-Coil dipole magnet which provided a maximum background field of 10 T at 4.2 K. Most importantly, the best IBS racetrack coil quenched at 4.2 K and 10 T with an operating current of 65 A, which is still as high as 86.7% of critical current of the short sample at 10 T. The details of the fabrication process and performance test results were presented in this paper. The performance test demonstrated the IBS conductor is a promising candidate for the application of high field magnets especially for future high-energy accelerators.

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High magnetic fields play a critical role in the development of modern science and technology, breeding many significant scientific discoveries and boosting the generation of new technologies. In the last few years, China has untaken a great deal of work on the application of Ultra-High-Field (UHF) superconducting magnet technology, such as for the Synergetic Extreme Condition User Facility (SECUF) in Beijing, the UHF nuclear magnetic resonance (NMR)/magnetic resonance imaging (MRI), nuclear fusion energy, particle accelerator, and so on. This paper reports the research status of UHF superconducting magnets in China from different perspectives, including design options, technical features, experimental progress, opportunities and challenges.

KEK has been conducting the design study of the beam separation dipole magnet, D1, for the High Luminosity LHC (HL-LHC) upgrade within a framework of the CERN-KEK collaboration. The D1 magnet has a coil aperture of 150 mm using Nb-Ti superconducting cable and the nominal dipole field of 5.6 T can be generated at 12 kA and 1.9 K. A field integral of 35 T·m is required. The development of the 2-m-long model magnet has been started since May 2013. This paper describes the development status of the short model magnet as well as advancement of the fundamental design studies.