Three experiments HIHEX (Heavy Ion Heating and Expansion), LAPLAS (Laboratory Planetary Sciences) and PRIOR (Proton Microscope for FAIR) are proposed by the HED@FAIR (High Energy Density at Facility for Antiproton and Ion Research) collaboration to study matter under extreme conditions of temperature and pressure at the FAIR facility in Darmstadt, Germany. A special beam strong final focusing and imaging system has to be installed at the end of the HED@FAIR beam line. One of the main components of these systems are four wide-aperture quadrupoles, which have to provide a focal spot of about a millimeter size. Within the framework of collaboration between IHEP and GSI at IHEP, these magnets will be designed and produced. The main parameters of the quadrupoles are: DC operating mode; the coil inner diameter is 260 mm; the minimal distance between quadrupole centers of two nearby magnets is 2500 mm; the integral of field gradient is 66 T. The prototype of the quadrupole coil is manufactured and its mechanical characteristics is studied. The 2D and 3D geometry of large-aperture quadrupole is optimized taking into account these studies. The general characteristics of this geometry are presented in this article.

Recently, there has been a need to develop scientific and medical accelerators using fast-cycling magnetic fields. The article studies the possibility of creating superconducting magnets based on new materials for generating such fields. One of the main tasks in the development of such magnets is to provide high quality of the magnetic field and to minimize dynamic losses in the coil and in the iron yoke. Here it is described the attempt to find the previous design of dipole magnet which satisfies to specification for the magnet of the rapid cycled proton synchrotron of the OMEGA project. The operating frequency is 25 Hz. Such fast ramping superconducting magnets for particle accelerators have not been considered before. Therefore, presented information may be of particular interest. The following options were considered in this study: steels for the iron yoke, superconducting wires, cable designs and various magnet configurations.

The experiments on matter under extreme conditions of density and temperature which are proposed by the HED@FAIR plasma physics collaboration at the new accelerator facility FAIR in Darmstadt, Germany require a strong final focusing system for energetic heavy ion beams. The main components of this system are four wide-aperture quadrupoles which have to provide a millimeter-size focal spot at the target. These superconducting magnets have 33 T/m central gradient with the inner aperture diameter of 240 mm and the magnetic length of 2 m. While designing the magnets, it has turned out that the magnet's aperture shall be increased to 260 mm, and the design distance between the magnet's centers of 2.5 m cannot be kept. Therefore it was necessary to reduce the physical length of the magnets and correspondingly, to compensate the integral field gradient by increasing the current. New requirements led to the development of a new magnets geometry which is presented along with parameters of the correction system and considerations about the magnet's cooling system.

The option being considered for the FCC-hh high energy injector is a superconducting synchrotron replacing the CERN SPS. The new machine would operate in a cycled mode also to feed experimental areas, much like the SPS nowadays. Due to this specific cycled operation, innovative design and development approaches is required to cope with the AC losses in the superconducting cables and iron yoke. The research joins experience accumulated at CERN and JINR in the design and operation of large systems operated at 1.9 K and in fast ramped and cycled magnets respectively. Minimization of the cycling power losses is particularly important. Total thermal losses should be limited to tentatively < 2 W/m at 4.2 K equivalent. The magnet design, and the results of preliminary tests on a candidate NbTi-wire for building a model magnet are presented and discussed.

The report overviews the recent SC-related R&D and production activity at IHEP. The scope of the paper extends over the items to follow. Two superconducting magnetic systems of Electron Lens for the Tevatron collider were developed, manufactured and successfully brought into operation. 42 cryogenic electrical feed boxes of various types for the Large Hadron Collider were developed, produced and commissioned. Results of development of fast-cycling SC magnets for the FAIR project are discussed. Operational experience acquired with the largest in Russia cryogenic system for cooling with a superfluid helium of SC RF separator for the beam transfer line #21from the U-70 machine is presented. Test-and-trial results with HTS current leads and dipole magnet employing Bi2223 as well as racetrack coils made of second-generation HTS are reviewed.

An accelerating complex of intensive beams of charged particles (Project Omega) is being developed at IHEP. The main part of this complex is a 3.5 GeV ring accelerator. The basic parameters of the dipole magnet for this ring are: 0.947 T central field in the rectangular region of 272 mm × 150 mm; the field ramp rate is 58 T/s; the injection field is 0.208 T; and the magnet length is 2 m. A comparative analysis of various designs of the dipole magnet is provided in this article for the purpose of selecting the most optimal geometry.

Eight four-layer racetrack coils from HTS-2G tape for electrical machines were developed, manufactured and tested. These coils were wound by YBCO HTS-2G tapes insulated by Kapton film. Influence of magnetic field and tension on the HTS-2G tape critical current as well as resistance of HTS-2G tape solder joints were measured. Effect of gluing of the coil turns by epoxy compound was studied. The application of HTS-2G racetrack coils is discussed.

Heavy ion heating and expansion and laboratory planetary sciences experiments are designed by the high energy density matter generated by heavy ion beams collaboration to study matter under extreme conditions of temperature and pressure at the FAIR facility in Darmstadt, Germany. A special final focusing system has to be installed at the end of the high energy density matter generated by heavy ion beams beam line for strong transverse focusing. To provide a focal spot of the size of a millimeter or less, a large focal angle is needed and, consequently, large-aperture high-gradient quadrupole magnets have to be used in the final focusing system. The Institute for High Energy Physics has considered the basic principles of the development of these magnets. The main parameters of the quadrupole are: the central gradient is 33 T/m; the inner diameter of the coil is 240 mm; the effective length of the magnet is 2 m; and the operating mode is dc. Design features of these quadrupole magnets are detailed: the superconducting wire, 2- and 3-D optimization of the coil and yoke geometry, and mechanical analysis. Preliminary considerations are given on the parameters of the protection and cooling systems of the magnets.

Results of the development of fast-cycling superconducting magnets for the FAIR project (European Research Centre of Ions and Antiprotons, Germany) are presented. Largest in Russia cryogenic system of 280 W refrigeration capacity at 1.8 K temperature for cooling with superfluid helium of superconducting RF separator for the OKA experimental complex to produce a separated Kaon beam from U-70 proton accelerator was developed and commissioned at Institute for High Energy Physics (IHEP). Experience of the cryogenic system operation is discussed.

FAIR (Facility for Antiproton and Ion Research), planned to be built at the site of GSI Darmstadt will include the 300 Tm fast-cycling heavy ion synchrotron SIS 300. In the frame of collaboration in FAIR project IHEP developed, produced and tested a prototype of SIS 300 fast cycling superconducting quadrupole. The main parameters of the quadrupole are 45 T/m central gradient, the gradient ramp rate of 10 T/m/s, the useful aperture of 105 mm, the coil inner diameter of 125 mm, 1 m length of the magnet. The one layer coil of the quadrupole is divided by three blocks and was wound by cored cable with 19 strands. The paper presents main characteristics of the magnet and results of its production and test.

As part of participation in project FAIR, IHEP has been developing designs of fast-cycling superconducting corrector magnets for the SIS 300 ring. There will be four types of corrector magnets: a steering dipole with vertical and horizontal dipole coils, a chromaticity sextupole, a resonance sextupole and a multipole magnet, consisting of quadrupole, sextupole and octupole coils. The paper presents requirements for the magnets, optimizations of the cross-section and 3D geometries, main magnetic characteristics, selection of the mechanical structure of the magnet to confine all forces affecting the coil. Since the magnets are fast-cycling, special attention is given to the choice of the current-carrying element by taking into account quench processes. Numerical analysis of AC losses and magnet temperature margin will also be presented.

SIS300 fast-cycling superconducting quadrupole magnet is developed at IHEP. Temperature margin and minimum quench energy are main parameters of stability of superconducting magnets. These parameters are important for the design and safe operation of superconducting magnets. But additional understanding for fast-cycling superconducting magnets is needed. To calculate the temperature margin one needs coupled numerical transient simulation of electromagnetic and thermal processes in the coil because critical temperature, operating temperature and AC losses are nonuniform over turns and their magnitudes vary in time during accelerator cycles. For calculation of the minimum quench energy the combination of the network model with thermal analysis is necessary, which allows one to model quench dynamics, including the effects of a current redistribution between strands of cable and spatial inhomogeneity of cable. Results for the temperature margin and the minimum quench energy for the magnet are presented and theirs dependence on various parameters is discussed.

IHEP has developed a design of a superconducting quadrupole magnet for the SIS 300, project FAIR. The main parameters of this quadrupole are: 45-T/m central gradient with the gradient ramp rate of 10 T/m/sec in the useful aperture of 105 mm and the coil ID of 125 mm; the geometric length of the magnet is 1 m. This work includes the analysis of the factors affecting field quality and heat releases of the quadrupole magnet for the SIS 300. Particularly, influence of the weak magnetic elements of the design on the field quality in the magnet is examined as well as the effect of generated heat releases in the resistive parts on the temperature margin in the quadrupole. Tolerances for the manufacturing accuracy of various geometrical parameters are presented. Examination of the parameters affecting the integral field quality is described. Presented law of dependence of low integral field multipoles on both thickness of the spacer and its position in the end parts allows one to quickly find optimized geometry with a viewpoint of the integral field quality.

A harmonic-coil measurement system is presented. The main task of the system is to determine the harmonic coefficients of the magnetic field in the aperture of the superconducting (SC) magnet such as dipoles, quadrupoles, sextupoles, and octupoles. The hardware includes a rotating shaft with a harmonic coil array, a motor controller linked to a personal computer (PC) via the CAN bus and a data acquisition controller linked to a PC by the USB bus. The system operation is based on a synchronization of a step motor rotating the shaft and a delta-sigma ADC, measuring a voltage induced during the coil's rotation. Such a mode provides an integral number of samplings per one step allows storing the row measurement data to a local disk for an off-line analysis and permits to change an interval of integration. Inspection of linearity of dependence between the positions of the shaft and a number of steps of the step motor was done. All subsystems, except the power supply (PS) are programmed using the Lab View software.

Fast-cycling magnetic fields, produced by superconducting magnets of the SIS300 accelerator, generate cable losses, which should be reduced by increase of contact resistances between wires in the cable. For this purpose various methods of cable interstrand resistance increasing are used successfully. But the values of contact resistances have strong influence on a stability, which could be characterized by minimum quench energy (MQE). From this point of view at IHEP it was carried out the experimental study of Rutherford type 19-strand superconducting cable with high value of contact resistances. Contact resistances and MQE measurements were performed. The description of features of samples, the measurement scheme and procedure are presented along with the experimental results.

Development of fast-cycling superconducting magnets with high field amplitudes and ramp rate makes severe requirements especially to material properties in order to improve field quality and to reduce AC losses. Analysis of experimental and literature data is fulfilled for magnetic characteristics of electric steels at different temperatures. Susceptibilities of stainless steels of different grades are examined as well as a tolerance on the value of the magnetic permeability. Mechanical, thermophysical and technological properties at room and cryogenic temperatures are presented. Comparison of steel characteristics, selected for the SIS300 quadrupole prototype, with the steels, used in the SIS300 dipole and steels, applied in the SIS100 prototype magnets is carried out. General advices to the choice of materials for electrical and stainless steels, used in a design of fastcycling magnets, are given.