Outer Solenoid Research Articles

The Influence of the Copper Stabilizer On the Current Carrying Capacity of REBCO Tapes and Stacks With Various Joints at High Ramp Rates

In this work, we experimentally investigate the current carrying capacity of single REBCO tapes and stacks made 5 12 mm REBCO tapes with a 25 μm copper stabilizer in liquid helium in comparison with those made of bare tapes with no stabilizer at current ramp rates up to 55 kA/s. The motivation for the research was checking the usability of REBCO stacks as basic sub-elements for high current superconducting cables operating in fast cycling modes at 4.2 K. An original experimental technique was employed to induce the extremely high ramp rates. During the tests, one or 5-folded stacks curled into rings 95 mm dia with different types of joints were charged in the external magnetic field generated by an outer solenoid at ramp rates up to 1.6 T/s. The curled REBCO stacks were either soft-soldered over their entire length or contained local joints only. The maximum screening current induced in the samples during the outer solenoid charging <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> was registered. Our experiments showed that the current carrying capacity of the REBCO tapes and stacks was strongly affected by the absence or presence of the copper stabilizer as well as the type of the joint. The reasons for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> limitation for the copper stabilized and bare samples are also briefly discussed.

Development of Coax Compacted Joint Assembly Process for the ITER Central Solenoid

The Central Solenoid (CS) is the core element of the ITER magnet system, contributed as in-kind procurement by the US Domestic Agency. Made up of six modular inter-exchangeable module coils, vertically stacked, forming a 15 m high and 4 m outer diameter solenoid, to be inserted inside the central tokamak core, after assembly of the 18 D-shaped Toroidal Field (TF) coils. Each module uses a Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn conductor internally cooled by circulation of supercritical helium at 4.5 K and supplied, for each module, with a 45 kA current by the way of two vertical leads exiting from the module outer radius. The available space between the CS and TF magnets being very limited, the US DA has developed a compact - so called Coax Joint (CJ) - devoted to connect the respective twelve module leads to the feeders located at top and bottom of the CS via dedicated busbar extensions. The CS coax joint assembly procedure as developed by US DA would make use of CS assembly onsite soldering process, to be executed under supervision of the ITER Organization (IO) in the tokamak assembly hall. In order to mitigate risks related to these soldering activities needed at assembly stage, IO has proposed an alternative assembly process based on indium wires compaction - so called Coax Compacted Joint (CCJ)- and initiated its prototype development and qualification in time. The hereby presented CCJ design solution is based on four copper quadrants, each including an embedded straight Rutherford-type superconductor cable-strip to transport the current. The current is transferred from the lead to the quadrants by the way of compacted indium wires. A steel jacket welded around the joint ensures the mechanical support as well as the needed leak tightness. The paper describes developments made by CEA under IO supervision from the conceptual design to the testing of joints in relevant cryogenic and operative conditions.

Double-Deck Metal Solenoids 3D Integrated in Silicon Wafer for Kinetic Energy Harvester.

A silicon-chip based double-deck three-dimensional (3D) solenoidal electromagnetic (EM) kinetic energy harvester is developed to convert low-frequency (<100 Hz) vibrational energy into electricity with high efficiency. With wafer-level micro electro mechanical systems (MEMS) fabrication to form a metal casting mold and the following casting technique to rapidly (within minutes) fill molten ZnAl alloy into the pre-micromachined silicon mold, the 300-turn solenoid coils (150 turns for either inner solenoid or outer solenoid) are fabricated in silicon wafers for saw dicing into chips. A cylindrical permanent magnet is inserted into a pre-etched channel for sliding upon external vibration, which is surrounded by the solenoids. The size of the harvester chip is as small as 10.58 mm × 2.06 mm × 2.55 mm. The internal resistance of the solenoids is about 17.9 Ω. The maximum peak-to-peak voltage and average power output are measured as 120.4 mV and 43.7 . The EM energy harvester shows great improvement in power density, which is 786 and the normalized power density is 98.3 . The EM energy harvester is verified by experiment to be able to generate electricity through various human body movements of walking, running and jumping. The wafer-level fabricated chip-style solenoidal EM harvesters are advantageous in uniform performance, small size and volume applications.

Design of a 56-GJ Twin Solenoid and Dipoles Detector Magnet System for the Future Circular Collider

An aggressive low-mass and high-stress design of a very large detector magnet assembly for the Future Circular Collider (FCC-hh), consisting of a “twin solenoid” and two dipoles, is presented. The twin solenoid features two concentric solenoids. The inner solenoid provides 6 T over a free bore of 12 m and a length of 20 m, enclosing the inner particle trackers and electron and hadron calorimeters. The outer solenoid reduces the stray field of the inner solenoid and provides additional bending power for high-quality muon tracking. Dipoles are included, providing 10 T · m of bending power in a 6-m mean free bore covering the forward directions for η ≥ 2.5 particles. The overall length of this magnet assembly is 43 m. The presence of several separate magnets in the system presents a challenge in terms of forces and torques acting between them. A rigid support structure, part of the cold mass, holds the inner and outer solenoids of the twin solenoid in place. The dipoles are equipped with lateral coils so that the net force and torque are reduced to zero. The second challenge is the substantial conductor and support structure mass used for containing the magnetic pressure. A doped aluminum stabilized and reinforced conductor is proposed, allowing minimal overall mass of the system. The result is a system consisting of a 53-GJ twin solenoid and two 1.5-GJ dipoles. The cold mass and the vacuum vessel mass of the twin solenoid are 3.2 and 2.4 kt, respectively; and the dipole cold mass weighs 0.38 kt. Various properties of the magnet system are discussed such as magnetic, mechanical and thermal properties, quench behavior, and assembly.

ANALYSIS OF THE PROCESSES IN AN INDUCTOR SYSTEM WITH AN ATTRACTING SCREEN EXCITED BY THE EXTERNAL CIRCULAR SOLENOID

Introduction. Developments in the field of magnetic-pulse treatment of metals (MPTM) are increasingly used in the modern technologies of production and repair of the aviation, automotive and other machinery, as they are environmentally friendly and energy-efficient in comparison with classical approaches. One of the main components of the device MPTM is a tool – inductor or the inductor system with an attractive screen (ISAS). The calculated dependences to calculate the inductor system with an attractive screen were taken from previous works. The ratios were obtained for the low-frequency mode of the excited fields, when is place their significant penetration through a thin-walled metal screen and a deformed workpiece. As it was shown earlier this mode is the most efficient from point of view of a force action on the object of a processing. Purpose . The theoretical analysis of the spatial-temporal distributions of the induced currents and forces of an attraction in the inductor system with an attractive screen excited by a flat circular solenoid located on the outside of the auxiliary screen. Methodology . The calculations are shown that the induced currents both in the screen and the workpiece are unidirectional and their interaction, in accordance with the law of Ampere determines the amplitudes of excited forces of attraction. Let’s note the effective validity of the considered inductor system excited by an external circular solenoid. With sufficient simplicity of the design take place rather high values of the developed forces of attraction and their averages. Results . Physically, a higher power efficiency of the system with an «external» coil in comparison with a system where coil is located in the internal cavity, can be accounted for lade of «failure» in the radial distribution of the excited forces. This «failure» in the design with a coil between the sheet metal is caused by its screening action against the forces of attraction between the induced currents. Practical value. It is shown that the inductor system with an attractive screen when it is excited by outer circular solenoid with a current of 50 kA ~ provides attractive power rates to about 1400 N on an area of sheet metal ~ 0.004 m 2 . The sufficiently high efficiency of the proposed options of an inductor system allows us to recommend it as a tool of the external straightening dents in the bodycar surfaces of vehicles.

New hybrid magnet system for structure research at highest magnetic fields and temperatures in the millikelvin region

The Helmholtz Centre Berlin (HZB) is a user facility for the study of structure and dynamics with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. At HZB a dedicated instrument for neutron scattering at extreme magnetic fields and low temperatures is under construction, the Extreme Environment Diffractometer ExED. It is projected according to the time-of-flight principle for elastic and inelastic neutron scattering and for the special geometric constraints of analysing samples in a high field magnet. The new hybrid magnet will not only allow for novel experiments, it will be at the forefront of development in magnet technology itself. With a set of superconducting and resistive coils a maximum field above 30 T will be possible. To compromise between the needs of the magnet design for highest fields and the concept of the neutron instrument, the magnetic field will be generated by means of a coned, resistive inner solenoid and a superconducting outer solenoid with horizontal field orientation. To allow for experiments down to Millikelvin Temperatures the installation of a 3He or a dilution cryostat with a closed cycle precooling stage is foreseen.

Modular Test Facility for HTS Insert Coils

The final beam cooling stages of a Muon Collider may require DC solenoid magnets with magnetic fields in the range of 40-50 T. In this paper we will present a modular test facility developed to investigate very high fields using double pancake coils made of commercially available 2G HTS materials. The conductor performance is presented, together with magnetic calculations and an evaluation of Lorentz forces distribution in the coils when inserted in an outer solenoid. Finally, results from tests in nitrogen and helium of a double pancake coil are presented up to an external magnetic field of 14 T.

Practical technique of pulsed field magnetization for bulk HTS application

We studied a pulsed field magnetization (PFM) of bulk HTS assembled into a synchronous motor as a field-pole. The PFM is essential to apply bulk HTS inside the machine as a practical technique. In the present study, we developed a PFM technique that is a usage of Controlled Magnetic density Distribution Coil (CMDC). The coil is composed of inner vortex coil and outer solenoid. We successfully obtained the trapped flux density with 1.3 T by the step-wise cooling method with CMDC at 38 K in the motor. The bulk was cooled by a condensed neon. In addition, we studied the PFM for Gd-bulk of 140 mm diameter. By using the CMDC, we obtained the trapped flux density distribution with regular shape. In this paper we report these advanced PFM techniques for a practical machinery applications.

Study of a new split-type magnetizing coil and pulsed field magnetization of Gd–Ba–Cu–Ohigh-temperature superconducting bulk for rotating machinery application

A new type of magnetization coil was designed to increase the maximum trapped magneticflux density and the total flux associated with an appropriate trapped magnetic fluxdensity distribution in a high-temperature superconducting bulk magnet. The coilis composed of an inner vortex-type coil wound with an outer solenoid coil. Apulsed current is applied to the inner or the outer coils. Successive applicationsof pulsed current from both the inner and the outer coils to only the inner coilprovide a distribution of trapped magnetic flux density closer to being conical inaddition to an increase of the maximum flux density and total integrated flux. Thepresent magnetization technique, the controlled magnetic flux density distributioncoil method, is useful for magnetized high-temperature superconducting bulkapplications such as in rotating machines, generators and magnetic separation.

Test results of the g-2 superconducting solenoid magnet system

The g-2 experiment dipole consists of a single 48 turn, 15.1 meter diameter outer solenoid and a pair of 24 turn inner solenoids, 13.4 meters in diameter. The inner solenoids are hooked in series and are run at a polarity that is opposite that of the outer solenoid, thus creating a dipole field in the space between the inner and outer solenoids. The dipole flux is returned by a C shaped continuous iron yoke. The superconducting solenoid coils are closely coupled to the solenoid mandrels and as such are subject to quench back. This report presents the results of various tests on the g-2 magnet system operating within its iron return yoke. These tests include quench back time constant measurements for the inner and outer solenoids and measurements of the response of the two-phase forced cooled helium cryogenic system to magnet quenches. The overall effectiveness of the g-2 magnet quench protection system was measured.

The large superconducting solenoids for the g-2 muon storage ring

The g-2 muon storage ring at Brookhaven National Laboratory consists of four large superconducting solenoids. The two outer solenoids, which are 15.1 meters in diameter, share a common cryostat. The two inner solenoids, which are 13.4 meters in diameter, are in separate cryostats. The two 24 turn inner solenoids are operated at an opposite polarity from the two 24 turn outer solenoids. This generates a dipole field between the inner and outer solenoids. The flux between the solenoids is returned through a C shaped iron return yoke that also shapes the dipole field. The integrated field around the 14 meter diameter storage ring must be good to about 1 part in one million over the 90 mm dia. circular cross section where the muons are stored, averaged over the azimuth. When the four solenoids carry their 5300 A design current, the field in the 18 centimeter gap between the poles is 1.45 T. When the solenoid operates at its design current 5.5 MJ is stored between the poles. The solenoids were wound on site at Brookhaven National Laboratory. The cryostats were built around the solenoid windings which are indirectly cooled using two-phase helium.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The g-2 storage ring superconducting magnet system

The g-2 {mu} lepton (muon) storage ring is a single dipole magnet that is 44 meters in circumference. The storage ring dipole field is created by three large superconducting solenoid coils. A single outer solenoid, 15.1 meters in diameter, carries 254 kA. Two inner solenoids, 13.4 meters in diameter, carry 127 kA each in opposition to the current carried by the outer solenoid. A room temperature C shaped iron yoke returns the magnetic flux and shapes the magnetic field in a 180 mm gap where the stored muon beam circulates. The gap induction will be 1.47 T. This report describes the three large superconducting solenoids, the cryogenic system needed to keep them cold, the solenoid power supply and the magnet quench protection system.

Dual multi-turn solenoids for the accurate magnetization measurements

A description is given of a pulsed magnet for a dual-coil system for measuring ferri- and ferromagnetic materials. In this design an extra coil is wound on a main solenoid coil, which produces a low field with long pulse width prior to the high field generated by the main coil. Since the rise rate of the magnetic field is small in the low-field region, the height of a spike voltage is reduced while the duration is elongated during the magnetization process. Consequently, the evaluation of saturation magnetization becomes accurate even for fields up to 55 T. The inner solenoid coil (Cu-Be) and the outer solenoid coil (Cu-Cr) are energized by capacitor banks of 75 kJ (10 kV) and 55 kJ (3 kV), respectively. The pulse magnet withstands more than 20 shots of a 50-T field. >

A rotating superconducting solenoid for 100 kWh energy storage

Two concentric superconducting solenoids, one rotating, the other stationary are analyzed for energy storage in space. Energy is transferred from the rotating mass through a shaft coupled to a motor-generator. The inner windings interact with the magnetic field of the outer solenoid to cancel the centrifugal and self-field forces of the flywheel rim. Current is induced in the inner solenoid thus requiring no separate power supply, while the current in the outer solenoid must vary with the angular velocity of the flywheel. The effect of the gap and scaling laws are developed. The efficiency in energy per unit mass is marginally attractive.

東北大金研ハイブリッド・マグネット

The High Field Laboratory for Superconducting Materials was established in April 1981 at Tohoku University in order to provide research facilities for the development of superconducting materials suitable for superconducting magnets for the plasma confinement in fusion reactors. Main facilities of this laboratory are three hybrid magnets up to 30 Tesla dc magnetic fields with inner bores from 32 to 52mm in diameter. The magnets consist of superconducting outer solenoids and water-cooled inner ones with a maximum steady power dissipation of 8MW. The design and construction of these three hybrid magnets have finished in last three years, and two of them (HM-3; 20T, 32mm bore and HM-2; 23T, 52mm bore) have already opened to scientists and engineers in the superconductivity and other fields. The rated field of the third hybrid magnet (HM-1) is 31 (or 29) Tesla in a bore of 32 (or 52)mm in diameter. By this hybrid system we have succeeded to produce 29.3 Tesla on April 21, 1984. Detailed descriptions are presented on the superconducting magnets, power supplies and cooling systems for them, water-cooled magnets, dc-high power source and water-cooled system for them, the monitoring and control system for the hybrid magnets including a super-minicomputer system, a hard-wired interlock system for the safety of human beings and machines, and so on. The fourth hybrid magnet system which aims at 35 Tesla as the next phase is also discussed.

The forced cooled Nb&amp;lt;inf&amp;gt;3&amp;lt;/inf&amp;gt;Sn superconductor and its magnet

The coil is a 0.6 m outer diameter solenoid, made up of eight double pancakes which will be tested in a forced cooled test facility that has been already constructed. The hollow conductor consists of a couple of Nb 3 Sn flattened cable in the center, a couple of Oxygen Free Copper stabilizer and the outside welded sheath. Some features of this conductor are as follows; the cooling mechanism by forced cooled supercritical helium and the high current capacity. The experimental results of this conductor and its magnet will be presented in this paper.

Status report on the forced flow high field test facility SULTAN

The construction of the Test Facility SULTAN - a common action of three European laboratories: ENEA (I-Frascati), ECN (NL-Petten) and SIN (CH-Villigen) is near completion. In this paper the status of the contributions of the different partners is described: (a) The SIN part of the facility, the cryogenic system the current leads, the power supplies and the data acquisition system has been put into operation. Results of these tests are presented. (b) The background field will be generated by two concentric solenoids. The ENEA contribution is concerned with the realization of the outer solenoid. This coil, which has been recently completed, will provide a 6 T field in the useful region, the remaining 2 T being supplied by the coaxial ECN insert coil. Details of the design, winding technique, hydraulic circuitry as well as instrumentation of both coils will be given and discussed. In addition the future upgrading to 12 T is outlined.

The design and construction of the outer solenoid of the ANU 30T electromagnet

The solenoid described here is the outer coil of a two coil system for generating a 30T magnetic field. Analysis showed that a homogeneous plane helix would be adequately strong. The Bitter principle of constructing a plane helix was chosen for practical reasons but difficulties arose due to loss of strength from the slits in the discs and the fact that circumferential strength had to be developed through friction between discs. The problems were overcome by adopting a design where each turn was made up of 16 discs interwound in a staggered pattern which dispersed the slits and provided adequate friction bonding. The effect of the slits is small reducing the strength to 15/16ths of an ideal continuous plane helix. It is shown that such a Bitter solenoid may fail either by expansion or by unwinding. The relevant factors involved in both modes are discussed and it is shown that unwinding is the most serious mode and cannot be remedied by increasing the number of discs per turn. A system of keying the end turns via torsion cylinders is described and illustrated. The solenoid is in fact a two-start helix with one turn each end four-start. Reasons for these features are described associated with current distribution and ease of insulation checking. The unusual construction technique is described and illustrated.

DESIGN OF TWO-REGION SOLENOIDS

A two-region solenoid consists of an inner solenoid placed within the bore of a large outer solenoid. It is shown that a two-region solenoid can always be built which has a higher magnetic efficiency (lower power consumption) than a single solenoid producing the same field over the same volume. The two-region solenoid also gives an important reduction in the stress level. These advantages are expected to be decisive in the design of large high-field cryogenic magnets.