The forced flow two phase helium cooling concept of superconducting magnets in parallel channels works successfully since the commissioning of the Nuclotron accelerator at the Joint Institute for Nuclear Research (JINR) in Dubna in 1993. We summarize its main cryogenic aspects and describe the optimization factors for further design of high or low current magnets designated for fast cycling or near DC mode. An overview of the main magnets design and related characteristic test results for the Booster and the Collider of the Nuclotron-based Ion Collider Facility (NICA complex) will be presented, as well as the measured magnetic field parameters. A brief information about the project status will be given.

The work is aimed at constructing a superconducting solenoid for Spin Physics Detector (SPD) at NICA project. The design of a superconducting solenoid made of a Nuclotron cable is proposed based on the technology developed at VBLHEP in the production of magnets for the Nuclotron accelerator and the NICA complex. Preliminary calculations of the magnetic field, forces, heat inflows, the maximum temperature of the winding after quench, etc. were performed.

The accelerator Nuclotron is one of the most important installations of the NICA accelerator complex in Dubna, which also includes a booster synchrotron and a collider. The superconducting booster synchrotron was put into operation at the end of 2020, the superconducting collider is in the final stage of assembly. Its launch is scheduled for late 2022. The magnetic system of the superconducting synchrotron Nuclotron has been in operation since 1993 and will require upgrade in the coming years. One of the possible options for upgrading the Nuclotron is to replace its magnets with magnets made of HTS material. A model superconducting quadrupole magnet with a winding of HTS material has been developed and manufactured at Veksler and Baldin Laboratory of High Energy Physics of Joint Institute for Nuclear Research. The design features and the first results of cryogenic tests of the magnet are discussed.

Serial tests of the SC-magnets of the NICA Booster (0.6 GeV/u, 211 m circumference superconducting booster synchrotron) started at the dedicated facility of LHEP JINR. Magnets' assembly and testing workflow are presented. First results of serial tests are presented and discussed.

Nuclotron-based Ion Collider fAcility (NICA) is a new accelerator collider complex under construction at the Joint Institute for Nuclear Research. The facility is aimed at providing collider experiments with heavy ions up to Gold in the center of mass energy from 4 to 11 GeV/u and an average luminosity up to 1 · 1027 cm-2s-1 for Au79+. The collisions of polarized deuterons are also foreseen. The facility includes two injector chains, a new superconducting booster synchrotron, the existing 6-AGeV superconducting synchrotron Nuclotron, and a new superconducting collider consisting of two rings, each 503 m in circumference. The booster synchrotron and the NICA collider are based on an iron-dominated “window frame”-type magnet with a hollow superconductor winding analogous to the Nuclotron magnet. The status of the serial production and test of the magnets for the booster synchrotron and the development of the full-size model magnets for the NICA collider is presented. The test results of magnets are discussed. The status of the construction of the facility for serial tests of superconducting magnets for the NICA project is described.

NICA is a new accelerator complex being under design and construction at the Joint Institute for Nuclear Research in Dubna. The actual design and the main characteristics of superconducting magnets for the NICA booster and collider are given. The magnets are based on a cold window frame iron yoke and a single-layered superconducting winding made from a hollow NbTi composite superconductor cable cooled with the forced two-phase helium flow. The first results of cryogenic tests of the magnets for the NICA project are presented.

NICA is a new accelerator complex being under design and construction at the Joint Institute for Nuclear Research (JINR) in Dubna. Full-size prototype dipole and quadrupole magnets have been designed, manufactured and tested for the booster synchrotron and the NICA collider. The magnets are based on a cold window frame iron yoke and a saddle-shaped superconducting winding made from a hollow NbTi composite superconducting cable cooled with a forced two-phase helium flow at T = 4.5 K. The maximal operating magnetic field in the aperture is 1.8 T. The magnetic field ramp rate of 1.2 T/s should be achievable. The quench history, AC losses as a function of the magnetic field ramp rate and pressure drop in the cooling channels of the magnets at different pulsed operation modes are presented.

The synchrotron SIS100 is one of the two basic accelerators of the future Facility for Antiproton and Ion Research (FAIR) at GSI in Darmstadt. The SIS100 should provide acceleration of high intensity U 28+ and proton beams for 0.5 s, with a pulse repetition rate of 0.6 Hz. In the accelerator magnetic system superferric 2 T dipoles of about 3 m length and 32 T/m quadrupoles of about 1 m length will be used. The magnet coils are made from hollow NbTi composite cable cooled with two phase helium flow at 4.5 K. The lattice comprises 108 dipoles and 168 quadrupoles. The elliptic beam pipe inner dimensions have been fixed at 130 times 60 mm 2 for the dipole and 135 times 65 mm 2 for the quadrupole. Both the dipole and quadrupole design approaches are based on improved versions of the original Nuclotron fast-cycling magnets and provide significantly less AC loss at 4.5 K, better quality of the magnetic field, and a higher long-term mechanical stability of the magnet coils. The results are based on the investigation of 1.4 m dipole and 0.4 m quadrupole Nuclotron-type magnet models. The status of the new magnets design and its manufacturing are presented. Essential features and new results are discussed.

The progress in the design of a fast-ramped, fast-cycling Cos-style 4 T dipole based on high current hollow superconducting cable is presented. New results obtained in the optimization of both the 40 kA hollow cable and the magnet coil structures are discussed. Experimental data from recent tests of the model dipole coil made from the NbTi keystoned wire are reported. The joint optimization of the angular distribution of the coil turns and the internal shape of iron boundary makes it possible to achieve a relative non-linearity of the magnetic field better than 5 • 10−4 within 82% of the coil aperture over a dynamic range from 0.3 T to 4.5 T. The diameter of the new hollow cable is 8.92 mm. It consists of 40 keystoned NbTi composite wires and a 3mm bore coolant tube. The designed operating current is 40.1 kA at 4.5 T. Full scale tests of the model dipole coil will be performed after completion of the necessary test facility upgrade. The actual maximum of 11.4 kA for the operation current is limited by the power supply and current leads of the test stand. The new current leads aimed at a current of 20 kA have been designed and manufactured.

New experimental results from the investigation of a model superferric Nuclotron-type dipole and quadrupole magnets are presented. The magnets operate at pulse repetition rate f = 1 Hz, providing the peak magnetic field B = 2 T and the field gradient G = 34 T/m in the dipoles and quadrupoles respectively. The superconducting coil is made from a hollow multi-filamentary NbTi cable cooled with two phase helium flow. Different possibilities were investigated to reduce AC power losses in the case of a cold iron yoke (T = 4.5 K). The achieved results are discussed. The value of 9 W/m has been obtained for dipole magnet with the yoke at T = 50 K. The first 50 K yoke quadrupole was designed and tested.

New experimental results from the investigation of a superferric window frame type dipole magnet with the operating parameters: B=2T, dB/dt=4T/s and pulse repetition rate f=1Hz are presented. The magnet SC coil is made from a hollow multifilamentary NbTi cable, cooled with two-phase helium flow. Special attention is devoted to minimization of AC power losses in the magnet to the specified value of 13W/m. The value of 9W/m has been obtained for a model magnet with the yoke at T=50K. Different possibilities were investigated to reduce the losses in the case of a cold iron yoke (T=4.5K). Other problems, connected with the magnetic field quality, mechanical and cryogenic stability of the magnet under SIS100 operating conditions are also discussed.

Experimental data of a fast cycling (f = 1 HZ) 2 T dipole Magnet based on a superconducting NbTi multi filament hollow cable cooled with forced two phase helium flow at T = 4.5 K and iron yoke at T = 80 K are presented. A new magnet design is proposed. The magnet yoke Made of laminated steel cone sists of two parts: the internal smaller part has close mechanical and thermal contact with the coil while the outer part is separated from the cold mass with a gap of 1 mm and cooled with liquid nitrogen.

Two new prototype dipole magnets for the proposed new fast cycling (f = 1 Hz) synchrotron at GSI in Darmstadt have been designed, fabricated and tested. The magnets are based on a window frame iron yoke cooled by liquid nitrogen and a superconducting winding made from a hollow NbTi composite superconductor cable cooled with forced two-phase helium flow at T = 4.5 K. The cold mass of the magnet is separated from the yoke by a small vacuum gap of 0.75 mm to 2.5 mm. A decrease of ac power losses by a factor of 2.3 in comparison with a standard Nuclotron dipole is obtained. The design features of two prototype dipoles as well as the test results are presented.

The results of the calculated analysis of cooling down the magnetic system of the synchrotron-Nuclotron from 300 K to 4.5 K are presented. The principle of the calculations is described. The calculated results are compared with the experimental data on cooling down the superconducting magnetic system of the Nuclotron. Recommendations of choosing an optimum condition of cooling down are given.

The results of design and tests of 2T superconducting model dipoles, operating at 1Hz, are presented. The magnets use a SC coil made from hollow superconducting cable, cooled with forced flow two-phase helium, and utilise a two section window frame iron yoke at different temperatures: one section at 4.5 K, the other at 80 K. Measurements of magnet training, AC losses, and magnetic fields are presented. Some beam pipe design problems as well as radiation effects are also discussed.