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The 9.4-T whole-body MRI superconducting magnet system is under manufacturing in the Institute of Electrical Engineering, Chinese Academy of Sciences (IEE CAS), which is used for the high-resolution imaging on human brain and metabolism. The superconducting magnet system with a warm bore of 800 mm is designed, which has the field homogeneity in a DSV of 400 mm better than 5 ppm after superconducting shimmed. In this paper, the magnet structure and superconducting coils manufacture process are introduced. The progress of wet winding and assembling of the magnet is presented. The optimized superconducting jointing technology is reported. During the coils manufacturing procedure, both the electrical insulation performance and the dimensional precision of the coils are controlled.

Flying Ad-Hoc Networks(FANETs) has the characteristics of multi-hop, self-organization and no center of the traditional ad-hoc network, and also has the characteristics of high-speed node movement, high-speed changes of topology and three-dimensional motion space. Bee colony algorithm is a kind of bionic intelligent optimization algorithm. The communication principle and honey collecting behavior of the bee colony can simulate the route discovery process in the ad hoc network, so it can be applied to the route discovery of the ad hoc network. However, the link stability of route discovery cannot be guaranteed due to the high-speed topology change caused by unmanned aerial vehicle (UAV) nodes moving at high speed. Because Bee colony algorithm cannot be directly applied to FANETs, this paper introduces the variable of link expiration time predicted by the extended Gaussian Markov mobility model into the fitness function of the bee colony algorithm, and then uses bee colony algorithm for the route discovery of FANETs in the three-dimensional environment. Through experimental simulation, the method improves the packet delivery rate and reduces the end-to-end delay.

A 9.4-T whole-body MRI superconducting magnet system is being manufactured in the Institute of Electrical Engineering, Chinese Academy of Sciences. The main magnet is an assembly of several coaxial coils. In this paper, three full-size dummy copper coils were wound and assembled to prove the coil's winding technology. A cryogenic experiment of the assembly was carried out by putting it into a liquid nitrogen container and testing the cryogenic mechanical properties and the electrical insulation performance. The winding and assembly process, testing apparatus, experimental procedure, and testing results of the dummy coils are discussed. The results show that the thermal contraction rates of the coils in axial and radial directions agree with the calculated results. The electrical insulation performance of the coils in cryogenic environment also meets the requirements.

There are very strong requirements for the magnets with very high magnetic field for experimental facilities used in the new generations of special material processing devices. A high magnetic field superconducting magnet has been designed with the center field of 8 T, warm bore of 100 mm, and warm split-gap of 100 mm. The maximum magnetic field in the superconducting winding is about 11 T. Two GM cryocoolers are employed to cool down the system. The magnet consists of two high temperature superconducting coils with commercially available Bi-2223 tapes and six NbTi superconducting coils. There is very strong attractive force between the split-pairs coils. The design, fabrication and test of the superconducting magnet are reported in this paper.

A NbTi superconducting magnet with long-length uniform axial field is designed and will be fabricated for high-frequency gyrotron experiments. The magnet has a warm bore of 90 mm in diameter and a uniform axial field length of 200 mm. The magnetic field on the 200-mm axial length is adjustable from 0 to 9.2 T, accommodating a wide range of gyrotron experiment frequencies. The magnet is composed of ten coaxial NbTi coils connected in series. Optimization of the field configuration is carried out to obtain the magnet parameters. Cryogenics of the magnet system is adopted as conduction cooling with a single GM cryocooler. The magnet design and integration are presented in this paper.

The oscillating heat pipe (OHP) with high thermal performance and easy manufacturing has been increasingly studied in the recent years. In this paper, the OHP for cryogenic application is investigated. An OHP system is manufactured with 3 sections of evaporator, condenser and adiabatic section. The temperature of evaporator and condenser and the gas pressure of the OHP are measured. The experiments with working fluid of nitrogen are carried out. When the heat input increases, the temperature and pressure increases were observed experimentally. When the dry-out takes place, the evaporator temperature rises quickly, the gas pressure drops sharply and the amplitude of the pressure oscillation reduces largely. The effective thermal conductivity is obtained and compared to other literatures. The relation between the effective thermal conductivity and the gravity, and the relation between the gas pressure and the gravity are attempted to interpret. The cryogenic OHP system shows much higher thermal performance than high purity metal, and it requires more study on the geometric optimization, the selection of working fluid and the operating limitations.

A magnetic resonance imaging (MRI) superconducting magnet with openness can reduce claustrophobia of a patient. To fabricate an open MRI magnet, a new magnet configuration with iron rings and pole plates balancing the force between the coil and the yoke, and correcting the field homogeneity has been proposed. An MRI magnet with the center field of 0.7 T generated by split-pair coils and yokes is fabricated. The coils are contained in the cryostat with separated vessels connected with two pipes. The coils are separated with a room temperature gap of 480 mm and the diameter spherical volume (DSV) of 300 mm in which the homogeneity is 3 ppm in peak-to-peak. The cryogenic system is cooled by one GM cryo-cooler to realize the zero boiling off liquid helium. In the paper, the detailed design, fabrication, and test will be reported.

A wide-bore conduction-cooled superconducting magnet was designed, fabricated, and tested for material processing applications. The superconducting magnet has a large clear warm bore of O300 mm, the maximum center field of 8 T, the homogeneity of 97% in homogeneous regions of O300 mm × 50 mm. The magnet is composed of three coaxial coils made with NbTi low-temperature superconducting wires. All the coils were connected in series and will be operated with a current of 82.2 A with a high level of stored energy, i.e., about 2.13 MJ. A passive protection based on a subdivided scheme is adopted to protect the magnet from damage caused by a quench. Two two-stage GM cryocoolers with the second-stage cooling power of 1.5 W is used to cool the superconducting magnet from room temperature to 4.2 K. In this paper, magnetic design, stress and strain analysis, quench protection, fabrication, and test are presented.

Strap suspension structures are widely used in superconducting magnet systems for high strength and low heat leak. A theoretical model is developed to design and analyze strap suspension structures. The supported cold mass, the tensile stress due to a cooldown, and a quasi-static acceleration load are considered in the model. In addition, the load conditions during transportation and operating the superconducting magnet system are analyzed. Design rules composed of mechanical strength, minimum resonant frequency, and heat load are presented. A suspension structure consisting of eight strap assemblies for a superconducting magnet is analyzed based on the model. The maximum pretension force is calculated, and the allowable accelerations for the maximum pretension are given. The vertical dynamic performance is better than the horizontal directions for the given strap configuration.

A superconducting magnet with the center magnetic field of 10 T and warm bore size of 100 mm was designed and fabricated. The magnet coils were fabricated with NbTi and Nb3Sn superconducting wires. The NbTi and Nb3Sn coils were manufactured with inter-winding support structure. A cryostat was designed and fabricated to accommodate the magnet with an outer diameter of 740 mm and height of 560 mm. The magnet system was cooled by a GM cryocooler with cooling capacities of 35 W at the first stage and 1.5 W at the second stage cold head. A pair of Bi2223 bulk high temperature current leads were employed to reduce heat leakage to the magnet. Total weight of the magnet system is about 230 kg. The superconducting magnet can be cooled down to 4.1 K in 90 hours with the cryocooler. The magnet was tested and reached the maximum operating current of 119.4 A, corresponding to a center magnetic field of 10.25 T in the warm bore. No quench was observed during the test process. It shows that the magnet stability is improved with the inter-winding support structure in magnet coil fabrication. The superconducting magnet system has been operating stably for several months. Extensive experiments on magnetic separation have been done on the magnet setup. In this paper, the detailed information of magnet design, fabrication and test are presented.

A conduction-cooled superconducting magnet was designed, fabricated and tested. A two-stage Gifford-McMahon (GM) cryocooler with the second-stage cooling power of 1.5 W at 4.2 K is used to cool the superconducting magnet from room temperature to 4.2 K. The superconducting magnet has the operating current of 105.5 A, the effective warm bore size of 250 mm, the maximum center field of 4.5 Tesla. The superconducting magnet will be used for the material processing. In this paper, the detailed design, fabrication and test are presented.

A superconducting magnet with a center field of 4.5 T cooled by GM cryocooler and operated in the persistent current mode has been designed, fabricated and tested for gyrotron. The superconducting magnet has a warm bore with diameter of 90 mm, the homogenous region with the diameter of 40 mm and length of 230 mm. The ratio of the axial field to the center field located at 180 mm is lower than 88%. In the other special points, the ratios of the radial field to the axial field should be less than from 3% to 11%. The thermally-controlled NbTi/CuNi switch with superconducting joint is connected to the conduction cooled magnet. In this paper, the detailed design, fabrication and test are reported.

A superconducting magnet with the center field of 9.4 T is designed and fabricated for 400 MHz Nuclear Magnetic Resonance. Superconducting coil with NbTi/Cu superconducting wire is employed and cooled by re-condensed liquid helium and the magnet system with the clear-bore of 54 mm. The pulsed tube refrigerator with separated valve is employed to cool the magnet system. The superconducting magnet has an active shield with high pure copper shield to protect during quench of the shielding coil. The paper reports the electromagnetic design, and fabrication is detailed.

Fiber Bragg grating (FBG) sensor for monitoring the electromagnetic strain in a low temperature superconducting (LTS) magnet was studied. Before used to LTS magnet strain sensing, the strain response of the sensor with 1.54- wavelength at liquid helium was experimentally studied. It was found that the wavelength shift showed good linearity with longitudinal applied loads and the strain sensitivity is constant at 4.2 K. And then, the hoop strain measurement of a LTS magnet was carried out on the basis of measured results. Furthermore, the finite element method (FEM) was used to simulate the magnet strain. The difference between the experimental and numerical analysis results is very small.

A superconducting magnet for the superconducting magnetic energy storage system (SMES) fabricated by NbTi monolithic conductor is cooled down and operated at the temperature of liquid helium. The large-scale superconducting magnet with four parallel solenoids was designed, fabricated and tested for the high storage energy density SMES. The superconducting magnet stores 2 MJ of energy with a current of 490 A and a peak magnetic field of 5.4 T. Two GM cryo-coolers cool the whole system to realize zero evaporation of liquid helium. The high temperature superconducting current leads of Bi2223 are used and cooled through one GM cryocooler. The ZnO resistor is used to protect the superconducting magnet. In the paper, the system of superconducting magnet is introduced in detail for the superconducting magnetic energy storage system.

In order to increase energy dumping speed, IGBT (insulated gate bipolar transistor) is used in quench protection of a 2 MJ superconducting magnet. 88 resistors, each connects in series with an IGBT, are connected in series-parallel connection to form a controllable varistor. On/off of the IGBTs are controlled by two single chip processors. Energy dumping with nearly constant magnet terminal voltage is realized in training quenches of the magnet. The necessary breaking capacity of the circuit breaker is also lowered. Details of quench protection electric circuit design and experimental results are presented.

For the goal of superconducting magnet applications in the advanced testing device for high temperature superconducting (HTS) wire and sample coils, a wide bore conduction-cooled superconducting magnet with available warm bore of phi 186 mm and center field of 5 T for the background magnetic field applications was designed and fabricated and tested. A sample cryostat with two GM cryocoolers is inserted in the background magnet. The system allows measurements to be performed in a repeatable and reliable fashion. The detailed design, fabrication and thermal analysis are presented in the paper.

Many areas of research have benefited from the application of conduction-cooled superconducting magnet technology. The middle and small-scale magnets immersed in the liquid helium will be replaced by the easy-operating conduction-cooled superconducting magnet due to convenient operation, lower operating cost and easy for user. For the goal of superconducting magnet applications in the advanced testing for high temperature superconducting (HTS) wire and sample coils, a wide bore conduction-cooled superconducting magnet with available warm bore of φ186 mm and center field of 5-6 T for background magnetic field applications was designed, fabricated and tested. The system allows measurements to be performed in a repeatable and reliable fashion. In order to support the high stress in magnet, the detailed finite element (FE) analysis with electro-plastic model is proposed. The sample cryostat is designed with cryofree. It includes two GM cryocoolers. The detailed design, fabrication and thermal analysis are presented in the paper.

A large bore NbTi superconducting magnet with liquid helium bath cooling has been developed for a micro-sized superconducting magnetic energy storage (SMES). The superconducting magnet has the clear bore of 480 mm, outer diameter of 550 mm and height of 500 mm. The magnet system is cooled in a compact cryostat with two GM cryocoolers. One of the cryocoolers is used to cool the thermal shielding. Another is used to re-condense the helium evaporation. A pair of high temperature superconducting current leads is used to reduce heat load to the cryostat. The operating current of the SMES system is rated at 325 A. Maximum energy storage is evaluated as 1.0 MJ at the rated operating current. Test results show that the stored energy can be dumped at the power of 7 kW to a dummy resistor load. This superconducting magnet system can be demonstrated as an Uninterruptible Power Supply (UPS). The superconducting magnet and the cryogenic system are described in this paper.

For the advanced testing of High Temperature Superconducting (HTS) wire/tape and sample coils, a wide bore conduction-cooled superconducting magnet with the available warm bore of 0186 mm and a center field of 5~6 T for background magnetic field applications was designed and fabricated. The magnet is composed of four coaxial coils. All the coils were connected in series and can be powered with a single power supply. The maximum magnetic field is 5.5 T. In order to support the high stress in superconducting magnet a detailed finite element (FE) analysis with electro-plastic model has been performed. A compact cryostat with a two-stage GM cryocooler was designed and manufactured for the magnet. The detailed design of magnet system is described in this paper.

A conduction-cooled superconducting magnet with the warm room of Phi 80 mm and the center field of 0~4 T was designed, fabricated and tested. The magnet can be operated for two different sets of coils which have different homogenous regions with lengths of 150 mm and 250 mm. The homogeneity of magnetic field is about plusmn0.25%. All the homogeneous regions are with the same starting point. The center field is decayed to 1/6-1/7 from the original point to 195 mm. The operating temperature of the magnet is defined at the 5.5 K for the conduction-cooled magnet to take into account the temperature rise during charging current. The thermal equilibrium of the superconducting magnet and cryogenic system is analysed to define ramping rate, operating current and margin of superconducting magnet. The detailed design and fabrication of the superconducting magnet for gyrotron are discussed. The test results show that the superconducting magnet can generate the requirement of magnetic field distribution.

We are carrying out a project to develop a conduction-cooled high temperature superconducting magnet system with an energy storage of 25 kJ. This magnet system will be used to investigate fast discharging performances. The magnet is constructed with 20 double pancakes. Each pancake is wound with Bi2223 tape. The magnet has an outer diameter of 212 mm and a clear bore of 108 mm. Cryogenics for the magnet system is designed to cool the coils with a GM cryocooler together with solid nitrogen. It is expected to operate the magnet system stand-alone. The operating current is designed as 110 A. It can generate a central magnetic field of 3.8 T at a temperature of 20 K. In this paper, the magnet design, coil fabrication and cryogenic system are presented.

High magnetic field superconducting magnet technology has been developed in the recent years for all kinds of special applications in China. In the paper, the successful development of high magnetic field superconducting magnet technology is presented.

A diamagnetic motor based on Meissner effect of low temperature superconductor (LTSC) in ultra low temperature has been studied. In this new superconducting motor, the stator is in the center of the rotor and the rotor is driven by the diamagnetic force. The principles and the different designs of this kind of motor are described in the paper. The analysis of electromagnetic configuration on a two-phase system design is carried out and the detailed data of the driving torquers of the motor are presented

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 Phi 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 mm. The homogeneity of magnetic field is about plusmn0.25%. 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

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 phi 226 mm. The magnet is installed in a vacuum cryostat with a phi 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 mass. 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 phi 100 mm. In this paper, the detailed design, fabrication and test are presented

Superconducting magnets cooled by cryocooler, without liquid helium, have been developed in recent years. This kind of magnet system is very easy and convenient to operate. The stability of the magnet depends on the balance between the cryocooler refrigeration capacity and the thermal loads. Based on thermal analysis for the magnet, study has been carried out on the stability of cryocooler-cooled superconducting magnet during current excitation.

The ultra-high-field superconducting magnets have been widely applied in scientific instruments for condensed matter physics. A superconducting magnet with the center field of 25 T in a warm bore-size of 32 mm in diameter has been designed for the Extreme Condition Experimental Science Facility (ExCES). The superconducting magnet consists of NbTi, Nb3Sn superconducting coils and YBCO high-temperature superconducting (HTS) insert operated at the 4.2 K. In order to prove the technical feasibility to achieve the target of 25 T, high-temperature superconductor YBCO and Bi2223 inserts have been designed, fabricated and tested in the operating temperature of 4.2 K. Inner diameter, outer diameter, and height for the YBCO insert are 40 mm, 68.9 mm, and 253 mm, respectively. The larger Bi2223 insert has the inner diameter, outer diameter, and height of 120 mm, 212 mm, and 268.8 mm, respectively. Tests at liquid helium temperature show that the YBCO and Bi2223 inserts can generate the center field of 5 T and 5.05 T, respectively. The assembly of the Bi2223 and YBCO insert coils can generate a center magnetic field of 7.6 T when tested at the liquid helium temperature. In this paper, the design, fabrication, and test of the HTS insert and the 25 T magnet are reported.

A project to develop a 9.4 T magnetic resonance imaging system is proposed for bioscience research applications. A whole body superconducting magnet system will be manufactured and test in the Institute of Electrical Engineering, Chinese Academy of Sciences (IEE, CAS). This magnet system features a room temperature bore of 800 mm in diameter, helium bath cooing, 9.4 T center magnetic field and passive iron shielding. The magnet is designed with radial layer-winding method. Five coaxial coils will be wound independently and assembled together as the main magnet. Coil length of the magnet is 3000 mm. In the magnet design, current density grading is performed to optimize the magnetic field distribution and stress level in the coil windings. The maximum magnetic field is 9.505 T, corresponding to an operating current of 224.515 A. The total magnetic energy storage is 138 MJ. Detailed magnetic and mechanic structure design as well as structure stress analysis are presented in this paper.

The applied pretension on the conductor and support condition during coil fabrication has a great effect on the stress state of the coil. Otherwise, the thermal contraction properties of mandrels and coils would cause residual thermal stress during cool down. A combined homogeneous cylinder method was used to analyze the mechanical performance of winding process for the condition of no mandrel support. A finite-element model of solenoid was created to calculate the stress of winding process and cool down. The mandrel support conditions of fixed support at ends of former and radial support along the whole inner surface of former were researched. Mechanical behaviors of one coil used for a 9.4-T magnetic resonance imaging magnet during winding process and cool down were studied based on the aforementioned approach.

Publisher Summary This chapter presents design and fabricating technique of a separator using the conduction-cooled high temperature superconducting (HTS) magnet for a National High-technology Program in China. The magnet is made of Bi-2223 double pancake coils, and has inner and outer coil diameters of 120 mm and 211.2 mm respectively and coil height of 202.8 mm. The superconducting magnet includes 20 double pancake coils. The operating current is about 87.8 A. This magnet is cryocooler-cooled with no liquid helium and should generate a magnetic filed of 3 T at a temperature of 20 K. The HTS magnetic separators have a variety of industrial applications, most notably in the pharmaceutical, environmental, chemical fields, and treatment for waste water in steel industry. The conceptual design and fabrication details of a conduction-cooled HTS Reciprocating Magnetic Separator are reported. Reciprocating magnetic separators are used in waste water treatment for special steel factory. The salient features and results of the electromagnetic, thermal, and quench protection analyses have been discussed.