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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 SIS300 ion synchrotron is the last stage of the FAIR facility for antiproton and ion research. Its magnet structure is based on rapid-cycling superconducting magnets, making it possible to increase the energy and time-averaged intensity of particle beams. In 2008, the Institute of High Energy Physics (IFVE) developed and successfully tested the SIS300 model dipole, which reached a central magnetic field 6.8 T with ramping 1.15 T/sec, which is higher than that of existing analogues. At the present time, the IHEP is developing with the financial support from Rosatom prototypes of rapid-cycling quadrupole and corrector magnets for SIS300 and is developing in collaboration with the Bochvar All-Russia Research Institute for Inorganic Materials (VNIINM) a superconducting conductor for these magnets and developing the SIS300 cryostating system, which will be built by Kriogenmash and Geliimash. The status of this work is 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.

In the frame of collaboration in the FAIR project IHEP has developed a design of a fast cycling quadrupole, which will be assembled together with corrector magnets in the united cryostat. This quadrupole is intended as the main unit for the SIS 300 ring. The 1-layer coil of the quadrupole is divided in three blocks and will be wound by a cored cable with 19 strands. The quadrupole creates a 45-T/m central gradient in 105-mm aperture. A possible simple quench protection scheme is shortly discussed with relation to the features of the developed quadrupole design. There will be various types of steering and corrector magnets in the SIS 300 ring. The geometries of the corrector and steering magnets are presented as well as their main magnetic parameters.

FAIR (Facility for Antiproton and Ion Research), planned to be built at the site of GSI will include the 300 Tm fast-ramping heavy ion synchrotron SIS 300. In the frame of a collaboration between IHEP (Protvino, Russia) and GSI (Darmstadt, Germany) IHEP developed, produced and tested a superconducting model dipole. The main parameters of the dipole are a two-layer coil, 100 mm inner coil diameter and 1 m length. The magnet is designed for 6 T central magnetic field with a 1 T/s operating field ramp rate. The nominal operating current of 6720 A (6 T central magnetic field) was reached after the third quench and critical current of 7738 A (6.8 T central magnetic field) was reached after the eighteenth quench. The critical current of the dipole did not reduce up to ramp rate of 1300 A/s (1.15 T/s). AC losses for different magnetic field cycles were measured too.

Main parameters for the SIS300 quadrupole, GSI, Darmstadt, project FAIR, are 45 T/m central gradient in 105-mm aperture, the effective length of the quadrupole is 1 m. Optimized geometric parameters of 1-layer magnet are presented both in the cross section and end parts. The coil consists of 3 blocks in one quadrant. Collars are a self-supporting mechanical structure. Integral multipoles are suppressed by central harmonics. Thermal and mechanical characteristics of the magnet are also presented.

Some technological and design peculiar properties have been discovered during working out design drawings and tooling for production of a short dipole model, which is being developed for synchrotron SIS 300, the FAIR project, GSI. These peculiarities should be taken into consideration during development of a full-scale prototype of the dipole. These features are related to both 2D and 3D geometries. This article presents some improvements that allow enhancing magnetic and mechanical characteristics, simplify processing complexity, and increase reliability and efficiency of the new design. Specifically, the field quality in the cross section is ameliorated. The length of the end parts is shortened, which gives larger effective length of the dipole.

The synchrotron SIS 300, developed for the Facility for Antiproton and Ion Research (FAIR) project at GSI, will use fast-cycling dipoles with 100 mm inner diameter coils, magnetic field amplitude of 6 T and a ramp rate of 1 T/s. This work presents the calculations of the magnetic and thermal characteristics of a 1 m model dipole with optimized 2D and 3D geometries. AC losses in the coil and iron yoke, as well as temperature margins, were analyzed. Production tolerances for the main geometrical parameters were also studied.

GSI, Darmstadt is preparing to build FAIR (Facility for Antiproton and Ion Research) which include SIS 300, a 300T - m fast-ramping heavy ion synchrotron. Dipoles for this ring will be 2.9 m long, producing 6 T over a 100 mm coil aperture and ramped at 1 T/s. The cable for these dipoles must have low losses and produce acceptable field distortions during the fast ramp. We plan to achieve this objective by using fine (~ 3 mum) filaments of NbTi in a wire with an interfilamentary matrix of CuMn to reduce proximity coupling and increase the transverse resistivity. The Rutherford cable have a thin stainless steel core and the wires will be coated with SnAg solder which has been oxidized, using a recipe similar to that developed at CERN, to increase the adjacent strand resistance Ra. Measurements of crossover strand resistance Re and Ra in cored cable with oxidized SnAg coating will be presented, together with data on critical current, persistent current magnetization and eddy current coupling in a wire with ultra fine filaments and a CuMn matrix in the interfilamentary region of the wire. These data will be used to predict losses and field distortion in the SIS 300 dipole and optimize the final design of cable for FAIR.

The last stage of the GSI Fast-Pulsed Synchrotron Project for FAIR (Facility for Antiproton and Ion Research) is the SIS 300 ring, which will use superconducting dipoles with 100mm aperture, 6 T magnetic field amplitude and 1 T/s field ramp rate. Stringent requirements on physical parameters and on the dependable service of the dipole necessitated using a cable with increased current carrying capability and low dynamic losses. A suitable geometry of the superconducting cable was found in that used for the outer layer of the Large Hadron Collider superconducting main dipole, supplemented by a stainless steel core for the reduction of the transverse contact resistance between the strands. The shape of the partially keystoned cable demands numerical methods for the optimization of the geometry in adaptation to the wide aperture dipole. The main characteristics of the optimized 2D and 3D geometry of the dipole are presented. Two grades of iron yoke steel were analyzed for use, in view of their resulting field quality. Thermal analysis of the dipole was carried out

An important part of FAIR (Facility for Antiproton and Ion Research), being developed at GSI, Darmstadt, Germany, is the fast-ramping heavy ion synchrotron SIS 300. The main elements of the SIS 300 magnetic system are 6 T, 2.6 m long superconducting dipoles, to guide charged particle beams on a path with a 50 m curvature radius. A model superconducting dipole, manufactured for the UNK project, was chosen to study the influence of bending on the magnet characteristics. The straight collared coil of this model magnet was tested, then bent with a 50 m curvature radius, and then retested. The main measured and calculated characteristics of the coil for both tests are presented. Test results showed similar characteristics, both in training and in ramp rate dependence, as well as in field quality of the straight and bent coils. There is a good agreement between measured and calculated results of the completed study

Short models of the UNK superconducting dipole reached a maximum central field of 6.5 T with 0.8 T/s ramp rate. It allows one to consider this magnet design as a basis for development of a superconducting dipole, which will have low heat loss and could be used for the production of fast-cycling magnetic fields, with 6T amplitude and 1 T/s ramp rate, for the new GSI synchrotron SIS-300. The dipole geometry makes it possible to independently suppress both central field and integral field low-order harmonics. The specific shape of the coil end parts enables a decrease of the maximum field in the end parts to the level in the straight part of the coil. Analyzes of magnet AC heating during the SIS-300 cycle, as well as heat transfer to the helium coolant, are presented. The magnet temperature margin and methods to increase it are discussed.

This paper describes the properties of SC cable with natural oxide on the strands developed for the UNK SC magnets and summarizes the performance of short and long magnets made of such cable. The coating was selected based on the studies of cable samples with various strand coating. Ten 1-m long dipoles and two 6-m long dipoles were manufactured using the cable with natural oxide coating of strands. These dipoles had low value of AC losses in the coil and reached the maximum magnetic field of 6.5 T in magnet aperture at the current ramp rates up to 0.8 T/s and 4.25 K temperature. The effects of interlayer splices and cable electrical insulation on the magnet ramp rate dependence are also reported.

Test of HTS dipole with coil wound by Bi-2223 tape was carried out. Volt-current characteristics of the dipole at various temperatures as well as results of magnetic field measurements are presented. A process of transition to normal state for the HTS coil was calculated.

The structure of a dipole magnet with an iron yoke, where the winding is made of a Bi-2223 high-temperature superconductor, has been developed and the magnet has been built at the Institute of High-Energy Physics. The magnet has also been tested. A magnetic field 0.9 T has been attained in the aperture at temperature 65 K and 1.9 T at 4.2 K. The special features of the magnet structure are described and the results of testing of the magnet in a submerged cryostat at different temperatures are presented.

The superconducting dipoles developed as part of the UNK project have reached a magnetic field 6 T at a rate of up to 0.8 T/sec. Experimental data are presented on the conditioning, rate dependences, and dynamic losses for magnets with two types of superconducting cable (zebra and oxide). Possible ways to decrease the heat release in a dipole operating in rapid-cycling magnetic fields are examined. The results of an analysis of heat release and temperature conditions are presented for a dipole with a winding made of improved current-carrying components.

IHEP has significant experience in the field of development and production of superconducting magnetic systems. In more than 25 years unique equipment has been created, covering the total cycle of magnet manufacture. The equipment includes cable and winding machines, presses, cryogenic system, facilities for test of materials and magnets. For the UNK project the pilot industrial batch's SC dipoles were produced. At present, IHEP develops magnets based on both NbTi and Nb/sub 3/Sn, as well as HTS devices.

A 600 A High Temperature Superconductor (HTS) current lead has been designed, fabricated and tested. The design of the HTS current lead is optimized to reduce the heat leak and to operate safely during fault mode conditions. The current lead consists of a resistive part cooled with helium forced flow and HTS part that is cooled with boiled off helium gas. The HTS part is composed of Bi-2223 with Ag 10 at.% Au alloy matrix. Results of the electrical and thermal tests of the current lead are presented.

Gesellschaft fur Schwerionenforschung (GSI) is planning to build FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany . This facility will include SIS 300, a fast-ramping heavy ion synchrotron with a rigidity of 300 T-m, with 6 T, 100 mm coil aperture 2.6 m long superconducting dipoles, ramped at 1 T/s . The fast ramp rate requires a magnet design that minimizes AC losses and field distortions during ramping. A two layer cos /spl theta/ magnet design, using a cored Rutherford cable, has been chosen. The paper will present the features of the magnet design that is to be built, the expected AC losses and field quality, and the experimental and analytical work that supports the choice of this design.

At present NIIEFA is designing superconducting correction magnets for UNK. UNK magnetic field correction system includes about 1500 various correction windings: dipole, quadrupole, sextupole and octupole. The magnet consisting of 3 concentric saddle type multipole coils with common iron yoke ("spool-piece"type) was selected as basic one. Each of the correction coils has the next optical force: sextupole-600 (T/m/sup 2/)/spl middot/m, quadropole-5.5 (T/m)/spl middot/m, dipole-0.68 T/spl middot/m. Total length is about 1.6 m, operating current /spl les/20 A. The 4 full scale models of the basic correction magnet with different types of conductors and various technique of winding have been built. This report describes the main design parameters of models and the particulars of their construction. The results of manufacturing and tests (quench behavior and magnetic field measurements) are discussed. >

The Tevatron Electron Lens (TEL) installed in the Tevatron at FNAL bends a 10-keV electron beam into and out of the antiproton path. The stringent requirements of the electron beam path demand extremely straight magnetic field lines over roughly two meters which then bend away to the gun and collector. A 6-Tesla superconducting solenoid and two normal-conducting solenoids, supplemented with several dipole and quadrupole correctors, were constructed at IHEP and subsequently assembled and tested at FNAL. Several testing methods, with an resolution of approximately 2 grad, confirmed the field profile to match computer models and meet necessary constraints. Visual inspection of the beam position and size on screens confirmed the measurements. This paper analyzes these results and relates them to the system requirements.

In the framework of collaboration between IHEP and FNAL, a magnetic system of the Tevatron Electron Lens (TEL) has been designed and built. The TEL is currently installed in the superconducting ring of the Tevatron proton-antiproton collider and used for experimental studies of beam-beam compensation.

The dipole magnet having a current carrying element, using a tape composite conductor on base of high temperature superconducting ceramics Bi2223 embedded in a silver matrix has been developed. The operating field of the dipole is 1 T at temperature of liquid nitrogen. The main characteristics of the used high temperature superconducting tape are displayed. The cross-section geometry optimization with goals to reduce field nonlinearities in aperture up to 10/sup -4/ and to minimize the value of magnetic field on the coil was carried out. The main results of the numerical simulations as well as of the properties of high temperature superconductors are presented.

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.

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.

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.

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.

Bi-2223 tapes with Ag-1 at.% Au and Ag-10 at.% Au matrices were fabricated for superconducting magnet current leads. The dependence of critical current on both temperature and magnetic field was studied. Electrical resistance, thermal conductivity, heat capacity and thermal contraction of the (Ag+Au) alloy matrix and HTS tapes were measured. Mechanical characteristics of HTS tapes at 77 K are presented.