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The Institute of Plasma Physics, Chinese Academy of Sciences was contracted by General Atomics Company to develop a superconducting feeder system containing a pair of 50-kA high-temperature superconducting (HTS) current leads for ITER central solenoid magnet test. These HTS current leads (HTSCL) are based on the previous ITER lead design experiences. However, the vertical assembly design of HTSCL which is different from ITER's horizontal assembly causes the water leakage in the insulation flange during the initial phase. Some improvements were recognized and expected to avoid the potential risk for further prototypes and series production of ITER leads. Some development experiences are shared in this paper. The HTS current leads contain BiSCCO AgAu matrix tapes tominimize the heat load to 4.5 K end. Its resistive part is cooled by 50-K helium. In the HTS part, the conduction cooling is adopted. The HTS current leads were integrated in the feeder system to perform 4.5-K full current test. The factory acceptance test was implemented to verify the highvoltage and thermodynamic performances. The maximum current of 55 kA was achieved. The test indicates that the helium mass flow consumption is 3.3 g/s per lead and the loss of flow accident time is approximate to 10 min at the nominal current with the stoppage of 50-K helium. The insulation flange passed the high-voltage test of 15 kV, while the leakage current is less than 1 mA after the improvement. More detailed test results will be shown in this paper. [ABSTRACT FROM AUTHOR]

The central solenoid (CS) is the backbone of the ITER magnet system. It consists of six independent coils held together by a vertical precompression structure that must react to tensile loads and provide sufficient preload to maintain coil-to-coil contact during all stages of plasma operation. Material selection and specifications applicable to the structural components of the precompression structure are particularly demanding. These include large forgings manufactured from a high-strength austenitic stainless steel (FXM-19) with a stringent specification in terms of microstructure and maximum allowed magnetic permeability. Stringent requirements are also imposed on all welded joints. In particular, the attachment welds of the cooling pipes to the structure are subject to challenging restrictions in terms of weld imperfections and geometry. They must induce limited distortion of the components and are submitted to inspections carried out in accordance with the most severe acceptance levels of applicable national and international standards. The results of a campaign of tests covering nondestructive and destructive evaluation of samples from different components and welds are summarized in this paper, particularly focusing on the quality achieved at the microstructural and macrostructural level. The influence of the microstructure on the final properties and on the inspectability of the material by nondestructive examinations is also discussed. [ABSTRACT FROM AUTHOR]

A central solenoid model coil (CSMC) is being developed to verify the large-scale Nb3Sn superconducting coil manufacture technologies for China Fusion Engineering Test Reactor in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences). The CSMC composed of Nb3Sn and NbTi hybrid superconducting magnet can reach to the maximum magnetic field 12 T. All of the Nb3Sn and NbTi coils are composed of pancakes windings, pancake joggles, and upper and lower leads. For the multipancakes, the radial dimensions are from 1500 to 3544.8 mm and the maximum axial height is 1545.4 mm. High manufacture accuracy must be acquired for coil continuous winding, i.e., the innermost and outermost circular turn surface profile tolerance is 2 mm and the conductor feeding tolerance is 0.5‰L. The winding R&D activities, including the continuous winding for the pancakes and the online forming for the joggles, have been conducted to optimize and finalize the coil design as well as to carry out the coil winding technology verification and improvement. Now, the continuous winding for double pancakes of the Nb3Sn inner coil has been finished. The details have been described in this paper. [ABSTRACT FROM AUTHOR]

The cable-in-conduit conductors (CICCs) that will be adopted for the ITER central solenoid (CS) coil of the ITER machine have been extensively characterized in the SULTAN facility in Villigen, Switzerland, by means of DC and AC tests. The AC measurements were performed superimposing a sinusoidal magnetic field, with the amplitude of 0.2-0.3 T and frequency in the range of 0.1-5 Hz, to a background constant magnetic flux density of 2 T and 9 T. This paper describes the analysis of the AC loss SULTAN tests of one CICC, identical to that used for the manufacturing of the CS Insert tested in 2015 in the CSMC facility in Naka, Japan. The numerical analysis of these experiments was performed by means of the THELMA code, by developing three models at different levels of discretization (sub-cables of different cabling stages and strands). The comparison between measured and computed losses allows one to estimate the interstrand contact conductances of the tested sample. The model provides a useful insight on the time and space distribution of the power dissipated in the conductor. [ABSTRACT FROM AUTHOR]

A novel active shimming method is proposed for the correction of magnetic field nonuniformity of superconducting (SC) magnet for magnetic resonance imaging. Active shimming utilizes several coils to correct specific field harmonic components appear in the inhomogeneous field, and each coil is usually designed independently to the others, and also takes no account of the presence of the main magnet coil blocks. However, the magnetic coupling among these SC shim coils exists, and also the interaction between those zonal even-order shim coils and the main magnet are particularly significant. This coupling/interaction can lead to the drift of main field and even a possible destruction of shim coils by quench due to tremendous energy transferred from the main magnet. In this paper, we attempt to develop magnetic decoupling technologies for the reduction of magnetic interactions between the shim coil and main magnet. Specifically, a hybrid optimization algorithm, including linear and nonlinear programming, is proposed to design a set of decoupled even-order zonal shim coils. The linear programming determines the globally optimal topology and preliminary position of the shim coils. Then, the nonlinear programming is applied to further optimize the position and the turn number of the shim coils, ensuring the designed coils are capable of correcting the unwanted field deviation. Taking the example of Z2 shim coil, compared with the conventional Z2 shim coil, the proposed method significantly reduces the mutual inductance between the Z2 shim coil and the main magnet. For the same field deviation in the tested case, the mutual inductance has been decreased from 83 to 2.3 H. We also further analyze the influence of system parameters and main magnet structure on the optimal topology of decoupled Z2 shim coil. Z4 and Z6 shim coils are also designed with excellent decoupling effect. In our future work, a whole set of active shim coils decoupled from each other and also the main magnet and will be designed and tested in the 9.4 T whole-body MRI system. [ABSTRACT FROM PUBLISHER]

An optimization design method of short-length actively shielded and open structure, superconducting MRI magnets is suggested in the paper. Firstly, the section of the solenoid coil is simplified as a current loop with zero section to solve a linear programming problem. The position coordinates in the radius and axial, and current for the loop can be calculated by the linear programming method. Then, the cross-section of the coil is optimized with a genetic algorithm to get appropriate section size. The method of linear programming, especially combining with genetic algorithm, reduces optimizing variables, which makes the design of a magnet feasible. Based on the method, a full open MRI superconducting magnet is designed with maximum radii of 0.8 m and 1.2 m. In the paper, the detailed optimization technologies are presented. [ABSTRACT FROM AUTHOR]

Canted–Cosine–Theta (CCT) magnet is an accelerator magnet that superposes fields of nested and tilted solenoids that are oppositely canted. The current distribution of any canted layer generates a pure harmonic field as well as a solenoid field that can be cancelled with a similar but oppositely canted layer. The concept places windings within mandrel's ribs and spars that simultaneously intercept and guide Lorentz forces of each turn to prevent stress accumulation. With respect to other designs, the need for pre-stress in this concept is reduced by an order of magnitude making it highly compatible with the use of strain sensitive superconductors such as \Nb3\Sn or HTS. Intercepting large Lorentz forces is of particular interest in magnets with large bores and high field accelerator magnets like the one foreseen in the future high energy upgrade of the LHC. This paper describes the CCT concept and reports on the construction of CCT1 a “proof of principle” dipole. [ABSTRACT FROM PUBLISHER]

The superconducting dipole magnets wound with HTS wires have been developed for a magic-angle-spinning NMR. The magnetic field of the dipole magnets is tilted from z-axis. Since the highly homogeneous magnetic field is required, the magnetic field of the dipole magnets is necessarily compensated by passive and/or active shimming. However, the compensation of all the components has not been reported. Usually, due to the axial symmetry of a solenoid magnet, only z component of the magnetic field is homogenized. In this paper, all the x, y, and z components of the magnetic field generated by the superconducitng dipole magnet are compensated because of the tilt from the z-axis. [ABSTRACT FROM PUBLISHER]

The A15-type superconductors (\Nb3\Sn, \Nb3 \Al) have been used to fabricate the 10-15-T high-field superconducting magnets. Due to the strain sensitivity of this type of conductors, minimization of the strain in conductors is an important issue to realize the highest critical current density during operation. It is also known that the superconductors in epoxy-impregnated coils exhibit much less critical current degradation than wire samples when subjected to transverse compressive stress, due to the stress buffer effect of the epoxy and insulation materials among strands. This paper presents analytical and numerical investigation of the stress and strain distributions in A15-type superconducting coils, which are usually wound with copper-stabilized Rutherford cable and are epoxy impregnated. Analytical formulas have been derived to calculate the strain in superconductors from the average strain in coils. In addition, a FEM simulation model has been built to get a clear view of the strain distribution between superconductors and the surrounding insulation materials. [ABSTRACT FROM PUBLISHER]

Stambaugh developed the Peng–Hicks concept of a fusion reactor based on a solid copper center-post spherical tokamak (ST). Using the promising results from the START experiment, they produced a vision for a path to fusion power. This path had two elements such as the ability to produce high fusion gain from an ST and of equal importance, the ability to demonstrate this in a small (and therefore relatively low cost) pilot plant device. In this paper, we review various attempts to pursue this vision, and try to elucidate the reason why success has not yet been achieved. However, we show that the advent of high temperature superconductors may overcome some of the problems, and we suggest a revised version of the small, low entry cost route to fusion power. [ABSTRACT FROM PUBLISHER]

The National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida designs, builds and operates the world's highest field dc resistive magnets, providing fields up to 36 T in pure resistive systems and up to 45 T in resistive-superconducting hybrids. The NHMFL has several resistive solenoid magnet projects underway presently, including upgrading existing magnets, designing the conical insert for the Helmholtz Center Berlin (HZB), and designing insert coils of the Series-Connected-Hybrid (SCH) for NHMFL. In addition, building the 28 MW all resistive magnets will start in 2012. The method, called irregular stacking, successfully used in the upgrade of the existing magnets in 2009, will be employed in the new upgrades and the design of the new magnet system. In this paper, the progresses of each project are briefly summarized at first. The new technology of irregular stacking is then discussed in detail. In the last section, the application of the technology in future upgrades and the design of the magnets are present. [ABSTRACT FROM PUBLISHER]

Now that ITER is entering construction, many of its systems are in the final stages of design and analysis. Among them the 31 feeders, which will be supplied in-kind by the Chinese ITER partner. The feeders supply the electrical power and cryogens through the warm-cold barrier to the ITER superconducting magnet systems. They are complex systems with their independent cryostats and thermal shields, densely packed with many components, such as the current feeds, the cryogenic valves and High-Voltage (HV) instrumentation hardware. Some of the feeder components are particularly critical and have been designed with great care. Among them the High-Temperature Superconductor (HTS) current leads, designed for unprecedented currents, the 30 kV class, Paschen-hard HV insulation and the bus bar support system, designed to react the multi-ton Lorentz-forces from the bus bars at minimal heat load. This paper discusses the design challenges for these (and other) key components of the ITER magnet feeders. [ABSTRACT FROM PUBLISHER]

MICE superconducting spectrometer solenoids fabrication and tests are in progress now. First tests of the Spectrometer Solenoid discovered some issues which could be related to the chosen passive quench protection system. Both solenoids do not have heaters and quench propagation relied on the “quench back” effect, cold diodes, and shunt resistors. The solenoids have very large inductances and stored energy which is 100% dissipated in the cold mass during a quench. This makes their protection a challenging task. The paper presents the quench analysis of these solenoids based on 3D FEA solution of coupled transient electromagnetic and thermal problems. The simulations used the Vector Fields QUENCH code. It is shown that in some quench scenarios, the quench propagation is relatively slow and some areas can be overheated. We describe ways of improving the solenoids' quench protection in order to reduce the risk of possible failure. [ABSTRACT FROM PUBLISHER]

A conceptual design of curved superconducting magnet for a carbon therapy gantry has been proposed. The design can reduce the gantry's size and weight and make it more comparable with gantries used for proton therapy. In this paper we report on a combined function, 5 T, superconducting dipole magnet with a 260 mm bore diameter that is curved 90 degrees at a radius of 1269 mm. The magnet superimposes two layers of oppositely wound and skewed solenoids like windings, energized in a way that nulls the solenoid field and doubles the dipole field component. Furthermore, the combined architecture of the windings can create a selection of field terms that are off the near-pure dipole field. Combined harmonics such as a quadrupole and sextupole are needed to adjust the beam trajectory. Ways to adjust the field and beam trajectory, magnet size and assembly, structure and pre-stress are considered. [ABSTRACT FROM PUBLISHER]

The new AEGIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) Experiment will be installed in the Antiproton Decelerator hall at CERN. The main goal is to measure the Earth's gravitational acceleration of antihydrogen atoms. The experiment consists of two high-homogeneity solenoids placed on the same axis. The 5 T magnet is part of a cylindrical Penning trap to catch and to accumulate antiprotons delivered by the decelerator. The antihydrogen is then produced in the 1 T region where sub-kelvin antiproton temperatures provided by the dilution refrigerator are required to form a slowly-moving beam of antihydrogen. The helium bath cooled superconducting magnets; the different traps and the dilution refrigerator are integrated in a common cryostat with an internal vacuum barrier between the insulating cryogenic vacuum and the very high beam vacuum. In addition, the magnet system has to guarantee a smooth transition between the 5 T and the 1 T magnetic field areas required for a loss-free transfer of antiprotons and positrons from the trapping region to the antihydrogen production area. In this paper the design of this AEGIS magnet system is presented and discussed. [ABSTRACT FROM AUTHOR]

The construction of the 1st phase Japan Proton Accelerator Research Complex (J-PARC) was completed. Three major experimental facilities, which have been utilized by users, are instrumented with the superconducting magnet systems; a muon transport solenoid in Materials and Life Science Experimental Facility, a superconducting spectrometer in Hadron Experimental Facility, and a 150 m superconducting beam line in Neutrino Experimental Facility. There are also several superconducting magnet systems proposed as part of future experiments at J-PARC. The paper briefly summarizes the current status of the superconducting magnet systems currently in operation, and introduces the superconducting magnet systems associated with the new proposals. [ABSTRACT FROM AUTHOR]

In the framework of the JT-60SA project, aiming at upgrading the present JT-60U tokamak toward a fully superconducting configuration, the detailed design phase led to adopt for the three main magnet systems a brand new design. Europe (EU) is expected to provide to Japan (JA) the totality of the toroidal field (TF) magnet system, while JA will provide both Equilibrium field (EF) and Central Solenoid (CS) systems. All magnet designs were optimized trough the past years and entered in parallel into extensive experimentally-based phases of concept validation, which came to maturation in the years 2009 and 2010. For this, all magnet systems were investigated by mean of dedicated samples, e.g. conductor and joint samples designed, manufactured and tested at full scale in ad hoc facilities either in EU or in JA. The present paper, after an overall description of magnet systems layouts, presents in a general approach the different experimental campaigns dedicated to qualification design and manufacture processes of either coils, conductors and electrical joints. The main results with the associated analyses are shown and the main conclusions presented, especially regarding their contribution to consolidate the triggering of magnet mass production. The status of respective manufacturing stages in EU and in JA are also evoked. [ABSTRACT FROM AUTHOR]

Magnesium diboride (MgB2) shows a wide application prospect in the field of low field DC application for its relatively simple structure and rather higher critical temperature than LTS. With the development of MgB2 composite superconductor manufacturing technology and cryogenic technology, developing conduction cooled superconducting MRI system with MgB2 composite superconductor is becoming increasingly feasible. An MgB2 superconducting magnet for MRI was developed. The MgB2 superconducting magnet is used to investigate the fundamental scientific problem of the MRI main magnet, including field uniformity and stability, influencing factors of MgB2 composite superconductor on field uniformity and stability. The superconducting magnet consists of 2 solenoids wound with MgB2 wire with the length of 60 m. The magnet has an outer diameter of 169 mm, an iron core diameter of 135 mm, and air gap of 32 mm. The superconducting magnet is fabricated and tested. The central magnetic field reaches 1.0 T when the current of the MgB2 magnet is 290 A. The central magnetic field is 0.39 T when the current of the MgB2 magnet is 100 A. In this paper, main magnet for MRI with MgB2 composite superconductor is analysed and proposed, including magnet design, test results, and field uniformity. [ABSTRACT FROM AUTHOR]

High power Stirling-type pulse tube coolers (HSPTCs) with oil-free linear compressors are promising solutions for cooling superconducting magnets. The cooling capacity of HSPTC ranges from 50 W to a few kilowatts below 100 K. At present the lowest refrigeration temperature of HSPTC has reached below 30 K. After a brief introduction of Stirling-type PTC, this paper reviews the newest developments in HSPTC. At the same time, the potential of HSPTC to be applied in cooling superconducting magnets is analysed. Possible future advances and prospective research emphases are also presented. [ABSTRACT FROM AUTHOR]

A superconducting coupling solenoid mounted around four conventional RF cavities, which produces up to 2.6 T central magnetic field to keep the muons within the cavities, is to be used for the Muon Ionization Cooling Experiment (MICE). The coupling coil made from copper matrix NbTi conductors is the largest of three types of magnets in MICE both in terms of 1.5 m inner diameter and about 13 MJ stored magnetic energy at full operation current of 210 A. The stress induced inside the coil assembly during cool down and magnet charging is relatively high. In order to validate the design method and develop the coil winding technique with inside-wound SC splices required for the coupling coil, a prototype coil made from the same conductor and with the same diameter and thickness but only one-fourth long as the coupling coil was designed and fabricated by ICST. The prototype coil was designed to be charged to strain conditions that are equivalent or greater than would be encountered in the coupling coil. This paper presents detailed design of the prototype coil as well as developed coil winding skills. The analyses on stress in the coil assembly and quench process were carried out. [ABSTRACT FROM AUTHOR]

Some superconducting magnets research at IMP (Institute of Modern Physics, CAS, Lanzhou) will be described in this paper. Firstly, a superconducting electron cyclotron resonance ion source (SECRAL) was successfully built to produce intense beams of highly charged heavy ions for Heavy Ion Research Facility in Lanzhou (HIRFL). An innovation design of SECRAL is that the three axial solenoid coils are located inside of a sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. Some excellent results of ion beam intensity have been produced and SECRAL has been put into operation to provide highly charged ion beams for HIRFL since May 2007. Secondly, a super-ferric dipole prototype of FAIR Super-FRS is being built by FCG (FAIR China Group) in cooperation with GSI. Its superconducting coils and cryostat is made and tested in the Institute of Plasma Physics (IPP, Hefei), and it more 50 tons laminated yoke was made in IMP. This super-ferric dipole static magnetic field was measured in IMP, it reach to the design requirement, ramping field and other tests will be done in the future. Thirdly, a 3 T superconducting homogenous magnetic field solenoid with a Φ70 mm warm bore has been developed to calibrate Hall sensor, some testing results is reported. And a penning trap system called LPT (Lanzhou Penning Trap) is now being developed for precise mass measurements. [ABSTRACT FROM AUTHOR]

Abstract-The efficient operation of high-power microwave (HPM) sources using slow-wave structures (SWSs) in low magnetic field has been an attractive aim pursued by HPM researchers. This paper presents the latest experimental results of an X-band oversized SWS HPM source operating at low guiding magnetic field with both power and efficiency enhancements. Driven by an electron accelerator with diode voltages of 450-900 kV, the generator operated with the output microwave power ranging from 0.5 to 3 GW and the efficiency being kept at about 25%. The optimized magnetic field was in the 0.5-0.75 T range, depending on diode voltages. Without the employment of superconductive-solenoid system, a very stable 100-Hz repetitive operation with 1.5-GW output microwave power was realized in the 1-s-burst mode. [ABSTRACT FROM AUTHOR]

The superconducting coupling solenoid to be applied in the Muon Ionization Cooling Experiment (MICE) is made from copper matrix Nb-Ti conductors with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm at room temperature. The magnetic field up to 2.6 T at the magnet centerline is to keep the muons within the MICE RF cavities. Its self inductance is around 592 H and its magnet stored energy is about 13 Mi at a full current of 210 A for the worst operation case of the MICE channel. The stress induced inside the coil during cool down and charging is relatively high. Two test coils are to build and test in order to validate the design method and develop the fabrication technique required for the coupling coil winding, one is 350 mm inner diameter and full length same as the coupling coil, and the other is one-quarter length and 1.5 m diameter. The 1.5 m diameter coil will be charged to strain conditions that are greater than would be encountered in the coupling coil. This paper presents detailed design of the test coils as well as developed winding skills. The analyses on stress in coil assemblies, AC loss, and quench process are carried out. [ABSTRACT FROM AUTHOR]

The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory in the UK. The coupling magnet is a superconducting solenoid mounted around four 201 MHz RF cavities, which produces magnetic field up to 2.6 T on the magnet centerline to keep muons within the iris of RF cavities windows. The coupling coil with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm will be cooled by a pair of 1.5 W at 4.2 K small coolers. This paper will introduce the updated engineering design of the coupling magnet made by ICST in China. The detailed analyses on magnetic fields, stresses induced during the processes of winding, cool down and charging, and cold mass support assembly are presented as well. [ABSTRACT FROM AUTHOR]

The superconducting magnetic energy storage (SMES) system has an attractive potential in power systems. Solenoid coil, one important configuration of SMES, can be simply built and provide highly stored energy per unit of the conductor. This paper suggests a novel two-objective optimization design model of solenoid coil. The objectives include the minimization of the solenoid volume and the uniformity of the magnetic field inside the magnet. Three constraints are considered, i.e., the energy requirement, the stray field in the surrounding region, and the quench condition. To optimize this highly constrained two-objective optimization design problem, Evolution Strategy (ES) has been used. The proposed sorting operator with Pareto competition divides the individuals into four groups: feasible Pareto (FP), infeasible Pareto (IP), feasible dominated (FD), and infeasible dominated (ID). FP solutions have the highest selection priority and ID solutions hold the lowest one. The annealing-like deterministic parameter control method for the acceptable tolerance of the energy error is also suggested to improve the constraints handling ability of ES. Numerical solutions show that the Pareto competition based ES can provide a set of feasible Pareto solutions for the two-objective optimization design model of SMES solenoids, among which the "best" one is to be extracted according to the designer's experience. [ABSTRACT FROM AUTHOR]

Abstract-The MICE focusing solenoids have three 4 K coolers (two for the superconducting magnet and one for the liquid absorber) and four HTS leads that feed the current to the focusing coils. The focusing solenoids produce large radial external fields when they operate with the polarity of the two coils in opposition (the gradient or flip mode). When the MICE focusing coils operate at the same polarity (the solenoid or non-flip mode), the fields are much smaller and parallel to the axis of the solenoid. The worst-case magnetic field affects the selection of the cooler and the HTS leads. This magnetic field can also determine the height of the service towers that house the three coolers and the four HTS leads. This paper shows the criteria used for Cooler selection, HTS lead selection, and the position of both the cooler and leads with respect to the solenoid axis of rotation. [ABSTRACT FROM AUTHOR]

Superconducting solenoids are increasingly used as focusing lenses in transport channels of linear RF accelerators of ions. If these accelerators employ superconducting RF cavities, each focusing lens is usually comprised of three coils connected in series: a main coil, which provides the needed focusing strength, and two bucking coils, that help to reduce magnetic field outside the lens. When a normal zone develops in any of the coils in a focusing lens, it propagates with a direction and a rate which depends on the coil and the specific part of the coil in which the quench first occurred. As a result of this propagation process (quenching), the temperature and/or voltage of parts of the lens can exceed safe limits, thus compromising lens reliability. On the other hand, the negative impact of quench events can be significantly mitigated if an external resistor is used to absorb a part of the energy stored in the magnetic field. This paper presents the main results of a solenoid quench protection study based on computational modeling of normal zone propagation in solenoid lenses being built for a superconducting linear RF accelerator under development at Fermilab. [ABSTRACT FROM AUTHOR]

The final beam cooling stages of a possible Muon Collider may require DC solenoid magnets with magnetic fields of 40-50 T in an aperture of 40-50 mm. In this paper, we study possible solutions towards creating DC fields of that order using available superconductors. Several magnetic and mechanical designs, optimized for the maximum performance are presented and compared in terms of cost and size. [ABSTRACT FROM AUTHOR]

The Broader Approach agreement between Europe and Japan includes the construction of a fully superconducting tokamak, the JT-60 Super Advanced (JT-60SA), as a satellite experiment to ITER. In particular, the whole Toroidal Field magnet system, described in this paper, will be provided to Japan by the EU. All the TF coil main constituents, i.e. conductor, winding pack, joints, casing, current leads, are here presented and discussed as well as the design criteria adopted to fulfil the machine requirements. The results of the analyses performed by the EU and JA to define and assess the TF magnet system conceptual design are reported and commented. Future work plan is also discussed. [ABSTRACT FROM AUTHOR]

Procurement of the ITER magnets is due to start at the end of 2007/early 2008, with the launch of the longest lead time items, the Nb3 Sn conductor and the TF coil windings. The base design for procurement was established in 2001, and the build up of the Cadarache ITER team has been accompanied by a review of the most critical, or controversial, features of the 2001 design. At the same time, an urgent R&D program has been launched to complete the necessary verification of the design solutions that are proposed. In this paper an overview will be presented of the main design features and drivers, and some of the recent issues and R&D results will be summarized. [ABSTRACT FROM AUTHOR]

The field strength and homogeneity of all the LHC superconducting magnets were measured as a part of the production control and qualification process that has taken place during the past four years. In addition to field measurements at room temperature performed on the integral of the production, a significant part of the magnets has been subjected to extensive magnetic measurements at cold. The measurements at cryogenic temperatures, generally performed up to excitation currents of 12 kA corresponding to the ultimate LHC energy of 7.6 TeV, were mainly based on static and dynamic field integral and harmonic measurements. This allowed us to study in detail the DC effects from persistent current magnetization and long-term decay during constant current excitation. These effects are all expected to be of relevance for the field setting and error compensation in the LHC. This paper reports the main results obtained during these tests executed at operating conditions. The integrated field quality is discussed in terms of distribution (average and spread) of the field strength and low-order harmonics as obtained for all the main ring magnet families (dipoles, main and matching quadrupoles). The dependence of field quality on coil geometry, magnet and cable manufacturer is analyzed. A projection of the field quality expected for the critical components in the machine is presented. [ABSTRACT FROM AUTHOR]

A pair of dual-purpose superconducting quadrupole magnets and a superconducting detector solenoid were fabricated and installed in Beijing Electron-Positron Collider Upgrade (BEPCII). The magnets are symmetrically inserted into the BESIII detector with respect to the interaction point. They are identical, iron-free, non-collared, multi-layered and active shielded superconducting magnets for the micro-beta focusing at the interaction region of the collider rings. Each quadrupole magnet is composed of seven coils at different operating currents wound layer by layer on a common cylindrical support. The magnet has an overall effective length of 0.96 m and provides a good field aperture of 65 mm in diameter. They are cooled by supercritical helium in order to eliminate the flow instabilities in constrained cooling channels. The BESIII superconducting solenoid magnet was designed to provide an axial magnetic field of about 1.0 T over the' tracking volume and to meet the requirement of particle momentum resolution to particle detectors. A single layer of coil, in-direct cooling by forced two-phase helium, high purity aluminum based stabilizer and NbTi/Cu superconductor is adopted for the solenoid. The solenoid is 3.4 m in diameter and 3.89 m in length. This paper presents the design of the superconducting magnets in the BEPCII as well as their cryomodules. The cooling system for the magnets is also discussed. [ABSTRACT FROM AUTHOR]

This paper presents the 2-D design of the SIS300 synchrotron dipole of the FAIR facility at GSI. The dipole has a length of 7.8 m, a field of 4.5 T, in a 100 mm bore, and is ramped at 1 T/s. The studies are performed by INFN (Frascati, Genova and Milano-LASA) in a R&D collaboration with GSI. The program started in 2006 (DISCORAP) and has as a final goal the construction and test of a prototype. Particular emphasis is given to the study of the field quality and of the losses during the ramping of the magnet. Some calculation methods and different codes for magnet design are evaluated and compared. [ABSTRACT FROM AUTHOR]

High-field superconducting solenoids have proven themselves to be of great value to scientific research in a number of fields, including chemistry, physics and biology. Present-day magnets take advantage of the high-field properties of Nb3 Sn, but the high-field limits of this conductor are nearly reached and so a new conductor and magnet technology is necessary for superconducting magnets beyond 25 T. Twenty years after the initial discovery of superconductivity at high temperatures in complex oxides, a number of high temperature superconductor (HTS) based conductors are available in sufficient lengths to develop high-field superconducting magnets. In this paper, present day HTS conductor and magnet technologies are discussed. HTS conductors have demonstrated the ability to carry very large critical current densities at magnetic fields of 45 T, and two insert coil demonstrations have surpassed the 25 T barrier. There are, however, many challenges to the implementation of HTS conductors in high-field magnets, including coil manufacturing, electromechanical behavior and quench protection. These issues are discussed and a view to the future is provided. [ABSTRACT FROM AUTHOR]

Since 2003, three years of the current 5-year national project for development of coated conductors using Y-system superconductors have passed and remarkable results have been achieved. In this paper, the current status and future prospects are reviewed. The group of Fujikura and SRL has worked on a long tape with high performance in the PLD-YBCO supercon- ducting tapes on the IBAD-GZO buffered substrates. The highest Ic × L value of the tape is over 50 k Am which is 212 m in length and 245 A of critical current (Ic). Additionally, a 500 m long IBAD-buffered tape with a reasonable in-plane texture was produced using a large scale IBAD apparatus by Fujikura. In the other group, long tape processing has been developed focusing on lowering production cost. An extremely high Ic value of 692 A was obtained in a short sample by the advanced TFA-MOD method on a CeO2 (PLD)/GZO(IBAD)/Hastelloy substrate. In the efforts for the long tape processing, a 25 m long tape with the Ic value of 100 A by a continuous reel-to-reel system and a 40 m long tape with 155 A by a batch system were realized. 100 m class long tapes were also obtained with the MOCVD and PLD-HoBCO processes. Both groups are aiming for 500 m long tapes with the high Ic value of 300 A/cm-w with a production rate of 5 m/h. Furthermore, feasibility studies for applications using coated conductors have already began due to the above mentioned success of long tape production. Several kinds of coils using the long coated conductors such as solenoid and pancake types and spiral shaped conductors for the cable were made. Reasonable high performance results were confirmed in the trials. New approaches on the preliminary studies for the applications of cables, transformers, motors and current limiters etc. are planned in this project. [ABSTRACT FROM AUTHOR]

This paper deals with the dielectric breakdown characteristics of superconducting coils for development of high voltage superconducting machines such as superconducting fault current limiter (SFCL) and superconducting transformer. The electrode systems are simulated to investigate the dielectric breakdown characteristics of solenoid and pancake coil. Dielectric breakdown tests are carried out on several basic electrode systems: needle-plane, sphere-plane, rod-plane, cutting bar-plane, and rounded bar-plane electrodes. These results could be applied to design the high voltage superconducting magnet system. Dielectric tests of turn-turn and layer-layer in solenoid coil are performed according to the groove depth, pitch length, and the distance between two layers. Dielectric tests of turn-turn with various insulation materials are also performed in pancake coil. In addition, the deterioration of high temperature superconducting (HTS) tapes and coils due to the electrical breakdown are investigated experimentally. It is proven that the HTS tape and coil could be robust to the electrical breakdown by the laminated metal. [ABSTRACT FROM AUTHOR]

CMS (Compact Muon Solenoid) is one of the large experiments for the LHC at CERN. The superconducting magnet for CMS has been designed to reach a 4 T field in a free bore of 6 m diameter and 12.5 m length with a stored energy of 2.6 GJ at full current. The flux is returned through a 10 000 t yoke comprising of five wheels and two end caps composed of three disks each. The magnet was designed to be assembled and tested in a surface hall, prior to be lowered at 90 m below ground, to its final position in the experimental cavern. The distinctive feature of the cold mass is the four-layer winding, made from a reinforced and stabilized NbTi conductor. The design and construction was carried out by CMS participating institutes through technical and contractual endeavors. Among them CEA Saclay, INFN Genova, ETH Zurich, Fermilab, ITEP Moscow, University of Wisconsin and CERN. The construction of the CMS Magnet, and of the coil in particular, has been completed last year. The magnet has just been powered to full field achieving electrical commissioning. After a brief reminder of the design and construction the first results of the commissioning are reported in this paper. [ABSTRACT FROM AUTHOR]

A 6 T conduction-cooled superconducting magnet was designed, fabricated and tested. The magnet is composed of two coaxial NbTi solenoid coils with identical axial length. Clear bore of the magnet is ϕ 226 mm. The magnet is installed in a vacuum cryostat with a ϕ 100 mm room temperature bore. The cryostat is designed in a support frame to be rotatable in a horizontal or vertical direction. A two-stage 4 K Gifford-McMahon (GM) cryocooler is used to cool down the superconducting magnet from room temperature to 4 K. The cooling power of the 4 K cold head is 1 W. A pair of Bi-2223 high temperature superconducting current leads was employed to reduce heat leakage into 4 K cold muss. Total cold mass of the superconducting magnet is about 115 kg. It takes 82 hours to cool down the magnet from 300 K to 4 K directly through the cryocooler. The superconducting magnet reached the designed central magnetic field of 6 T in the warm bore when a 115 A energizing current is applied. The superconducting magnet was stably operating more than 275 hours continuously in full field. Further, a Nb3Sn coil insert to be installed, the magnet can provide the maximum center field of 10 T with effective warm bore of ϕ 100 mm. In this paper, the detailed design, fabrication and test are presented. [ABSTRACT FROM AUTHOR]

The development of a high frequency, high harmonic gyrotron based on a superconducting magnet is described. A conduction-cooled superconducting magnet with the warm room of Φ 80 mm and the center field of 4 T was designed and fabricated. The superconducting magnet has two homogenous regions with length of 150 mm and 250 ram. The homogeneity of magnetic field is about ±0.25%. All the homogeneous regions are with the same starting point and the field is decayed to 1/6–1/7 from the front point of the homogeneous region to 195 mm. This paper describes the design and fabrication of the superconducting magnet for Gyrotron. [ABSTRACT FROM AUTHOR]

A magnet system comprising a 2 T superconducting solenoid for a target spectrometer and a large aperture dipole magnet for a forward spectrometer is being developed for the PANDA experiment at GSI. The inner radius of the solenoid coil is 1.1 m. The solenoid is of a split type to provide a warm bore between the coil parts for the target. An energy of 23 MJ is stored in the magnet. The Dipole Magnet will provide a bending momentum of 2 T · m. The magnet is of the ‘H-type’ with a water-cooled winding. The paper covers magnetic field and forces calculations as well as strength analysis and description of the magnet system components and their implementation. [ABSTRACT FROM AUTHOR]

A conceptual design is presented for a distributed reinforcement conductor that enables the use of presently available, high current density, round cross-sectional wire for high field superconducting magnets. One of the disadvantages of providing separate structural reinforcement on the outer diameter of layer wound coils is the inherent thermal and mechanical stresses developed at the interface between the superconductor and reinforcement. This paper proposes a new concept, a single wire in conduit (WIC), for a distributed reinforcement conductor configuration which not only eliminates the problem of interface stresses, but introduces coolant directly to the superconducting wire where it will be more effective in providing a stable operating environment. The materials required for the proposed configuration are discussed and a conceptual design for a 30 T superconducting solenoid using the WIC conductor is described. The areas of WIC conductor technology requiring development and characterization are discussed. [ABSTRACT FROM AUTHOR]

The Korea Superconducting Tokamak Advanced Research (KSTAR) Central Solenoid Model Coil (CSMC) has been developed to validate the design of KSATR CS coil. The thermo-hydraulic characteristics were analyzed for the KSTAR CSMC. The major thermo-hydraulic parameters of the coil are AC losses, strand temperature, coolant temperature, pressure drop and temperature margin. A numerical code has been developed for the thermo-hydaulic analysis of the KSTAR CSMC according to the operating conditions. In this paper, the description of the thermo-hydraulic analysis models and analysis results of CSMC are presented. The total energy deposition due to AC losses in CSMC winding will induce a flow reversal of supercritical helium. The minimum temperature margin is estimated approximately 0.5 K. The maximum temperature in CSMC winding is about 7.6 K. [ABSTRACT FROM AUTHOR]

A 1.5 T thin superconducting solenoid has been in operation as part of the BaBar detector since 1999. This magnet is a critical component of the BaBar experiment. A significant amount of magnet operating experience has been gathered. The average availability of this magnet currently approaches 99 percent. This paper describes the historical frequency and modes of unplanned magnet ramp downs and quenches. It also describes steps that have been taken to mitigate these failure modes as well as planned future improvements. [ABSTRACT FROM AUTHOR]

The ATLAS particle detector in the Large Hadron Collider at CERN features a hybrid system of four superconducting magnets: a Central Solenoid surrounded by 2 End-cap Toroids and a Barrel Toroid. The magnet system dimensions are 20 m in diameter and 26 m in length. With its 1.55 GJ stored energy in air, it actually is the largest superconducting magnet in the world. The construction of the magnets has started in 1998 and will end in 2006 with the completion of the installation underground. Currently, in October 2004, practically all magnet parts are manufactured and delivered to CERN for final integration. The first two out of 8 full size 25 × 5 m² size coils for the Barrel Toroid have been completed and tested while the other 6 are near to completion as well. The production of the so-called End-Cap Toroids is progressing well. The Central Solenoid is complete and ready for installation. The installation underground of the entire system including its services has commenced. In the paper the main features of the magnets, their common infrastructure and services are reviewed and the status of realization presented. [ABSTRACT FROM AUTHOR]

Electrodynamic Maglev systems (EDSs) and passive magnetic bearings (PMBs) generate magnetic forces by induction through the movement of permanent or superconducting magnets past conducting coils. Nearly all EDSs and PMBs use a null flux coil exposed to changing magnetic fields in the rotation or travel direction. An unusual variant eliminates discrete coils by using field structures that do not vary in the direction of rotation. We discuss the design and analysis of this homopolar variant in this paper. We believe that this is the first combined passive damper/axial support bearing, and we present here the first generalized solution of its governing equations. Actuated brushes during motoring and generating simplify energy exchange when the device is used for flywheel energy storage. [ABSTRACT FROM AUTHOR]

This paper compares the advantages and shortcomings of shape optimization method and topology optimization method for HTS solenoid design. For both methods critical current condition of superconducting material is taken into account for accurate analysis and design. Details of each method are explained including design variables and sensitivity analysis. With these methods, it is possible to design HTS solenoid that makes efficient use of superconducting material. Design results show that it is best to use topology optimization method for basic layout design and use shape optimization method for fine-tuning of the basic layout. [ABSTRACT FROM AUTHOR]

A high-Tc superconducting (HTS) DC reactor has been developed as a part of DC reactor type superconducting fault current limiter (SFCL) rated on 6.6 kV/200 A. The DC reactor was a solenoid coil and was wound with a 4-parallel stacked tape. This coil has 5 layers which are connected in series each other. The inductance of the coil is about 84 mH. This paper deals with the design, fabrication and testing of the DC reactor. For this design of the coil, a prototype solenoid coil had been used. Using the experimental result of a prototype solenoid, the number of stacks and the inductance were designed. The winding machine for the HTS solenoid was manufactured. Using this machine, the large-scale HTS solenoid using a Bi-2223 tape was fabricated successfully. Characteristics of the fabricated coil were observed through a measurement of voltage as current transportation. [ABSTRACT FROM AUTHOR]

The High Temperature Superconducting (HTS) electric equipment using Bi-2223 wire successfully commercialized 1st generation HTS wire, has been developing by many research groups. HTS coil is one of the most important parts in HTS electric equipment. To enlarge the critical current, the operating temperature of the equipment tends to go down and number of HTS wire tends to increase. Thus, it is very important to determine the whole critical current of HTS coil for the stable operation of HTS equipment. The whole critical current of multi-stacked wire of HTS solenoid coil is not equal to the sum of the critical current of each stacked wire because of nonuniform current sharing occurs in multi-stacked HTS wires and each HTS path does not has the same critical current. In this paper, current sharing in two types of 5-stacked HTS solenoid coils, made up of 1 copper layer which is a current buffer layer of HTS coil and 4 HTS wire layers, was analyzed. One was wound with Bi-2223 wire insulated with polyimide tape and the other was wound with noninsulated Bi-2223 wire. All of the Bi-2223 wires were reinforced with stainless steel. The simulation results of current sharing in multi-stacked HTS coils coincided well with the experimental results. Based on these results, the current sharing ratio of large scale HTS coil was also expected. The copper layer acted as a good current path when all the HTS wires were quenched. [ABSTRACT FROM AUTHOR]

CMS (Compact Muon solenoid) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive features include a 4 T superconducting solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000 ton return yoke. The magnetic field is achieved by a 4-layer supercondticthig solenoid made of a high purity aluminum (HPA) stabilized Rutherford type superconductor. The magnet is operated at 4.5 K, with a nominal current of 20 kA, for a total stored magnetic energy of 2.7 GJ. Due to the high magnetic forces at nominal field inside the winding pack, the structural component is the conductor itself to get a self-supporting winding structure. The mechanical reinforcement is made from aluminum alloy directly welded to the superconductor by Electron Beam (EB) welding technology before the winding operation. The external support cylinders also take part to the mechanical integrity. At each step of fabrication of the CMS conductor, the mechanical properties of the components and bonding between them are measured by destructive testing on short samples, in complement of continuous monitoring during production. This paper presents the results of the superconducthig cable to pure aluminum shear testing, the tensile testing of the EN AW 6082 aluminum reinforcement, the insert to reinforcement shear testing, and the tensile testing of the full conductor before and after heat treatment induced during coil curing, possible influence of the EB welding on the mechanical properties of the final conductor is investigated. Residual Resistivity Ratio (RRR) measurements of the HPA stabilizer are presented. Mechanical properties and equivalent RRR of the CMS conductor are presented for comparison with conductors of other geometry. [ABSTRACT FROM AUTHOR]

One possible application of Nb3Sn, whose superconducting properties far exceed those of NbTi, is the fabrication of short and powerful quadrupole magnets for the Interaction Regions (IR) of large particle accelerators. In some cases, as in the future linear collider TESLA, the quadrupole magnets are inside the detector solenoid and must operate in its background field. This situation gives singular Lorentz force distribution in the ends of the magnet. To learn about Nb3Sn technology, evaluate fabrication techniques and test the interaction with a solenoidal field, DAPNIA/SACM at CEA/Saclay has started the manufacturing of a 1-m-long, 56-mm-single-aperture quadrupole magnet model. The model relies on the same coil geometry as the Lilt arc quadrupole magnets, but has no iron yoke. It will produce a nominal field gradient of 211 T/m at 11,870 A. The coils are wound from Rutherford-type cables insulated with glass fiber tape, before being heattreated and vacuum-impregnated with epoxy resin. Laminated collars, locked around the coil assembly by means of keys, restrain the Lorentz forces. After a recall of the conceptual design, the paper re- views the progress in the manufacturing and test of the main com- ponents as well as in the design and delivery of the main tooling. The first coil is expected to be wound and heat treated during the last quarter of 2003. [ABSTRACT FROM AUTHOR]