Donghui Jiang

A High-Temperature Superconducting Maglev Ring Test Line Developed in Chengdu, China

A 45-m-long high-temperature superconducting (HTS) Maglev ring test line, named “Super-Maglev,” has been successfully developed in Chengdu, China, in February 2013, 12 years after the birth of the first man-loading HTS Maglev test vehicle. The Maglev vehicle (2.2 m in length, 1.1 m in width) is designed for one passenger with a levitation height of 10–20 mm; the permanent-magnet guideway (PMG) (45 m in length, 0.77 m of track gauge) is a racetrack shape with a curve radius of 6 m; the driving is accomplished by a linear induction motor with a maximum running speed of 50 km/h. The linear motor is composed of four submotors installed at one straight section in the middle of the double PMGs, and the total length is 3 m. This second-generation HTS Maglev vehicle system is highlighted by the cost-performance and the wireless multiparameter onboard monitoring function. The current same-level load capability has been achieved over a small-section low-cost PMG whose cross-sectional area is only 3000 mm2. On the vehicle, parameters of levitation weight, levitation height, running speed, acceleration, lateral offset, online position, and total running distance of the vehicle are real-time monitored and displayed on the onboard tablet computer. The system component and test data are reported in detail in this paper.

Research of Radial High Temperature Superconducting Magnetic Bearings for Cryogenic Liquid Pumps

The mechanical bearing in the cryogenic liquid pump has short working life due to the low temperature environment. For conquering the disadvantage, the radial high temperature superconducting magnetic bearing (HTSB) is designed to be used in the cryogenic pump. The high temperature superconductors (HTSs) in the HTSB are cooled by the cryogenic liquid directly. The introduced cryogenic liquid pump can constrain the heat leakage. The equipment for the kinetic characteristics of the HTSB is introduced, and it can measure the axial forces of the HTS at different rotation speeds. Basic mechanical principle of the rotor of the pump is analyzed.

Characteristics of Dynamic Response of Balanced and Unbalanced High-Tc Superconducting Maglev System

Understanding the characteristics of dynamic response of a high-Tc superconducting (HTS) maglev vehicle subject to different operating conditions is of utmost importance for advancing its application in the further transportation system. Based on a reduced HTS maglev model, this paper experimentally reproduced the balanced and unbalanced conditions of on-board passengers/freight by loading and unloading the weight to the model at different locations, namely, at the central location of the model for balanced condition and at the front of the model for unbalanced condition. Making recourse to the B&K vibration analyzer (3560C) and laser displacement acquisition equipment, the dynamic signals, i.e., acceleration, displacement, and resonant frequency of the model subject to respective balanced and unbalanced condition were sampled and analyzed. It was found that, the distribution of on-board weight affects the dynamic response of the model significantly and as expected, the unbalanced distribution does harm to the stability and thus the carrying capability of the maglev vehicle.

Hydrostatic Pressure Effects on the Critical Current of YBCO Coated Conductor Wire

The critical current density of optimally doped bulk YBCO superconductor has been found to increase with the application of external hydrostatic pressure. This paper reports the transport measurements of the critical current (Ic) of YBCO in the form of a coated conductor (CC) wire under hydrostatic pressure up to 0.24 GPa at 77 K. No noticeable change was observed in both the Ic and n-value of the CC sample in the studied pressure range. Two possible scenarios are discussed to explain the observed effect.

Influence of Auxiliary Permanent Magnet on the High-

The high-Tc superconductive (HTS) hybrid Maglev with the auxiliary permanent magnet (PM) is a useful method to improve the system load density and stiffness. The auxiliary PM changes the magnetic circuits and increases the instability of the Maglev system. To investigate the levitation performance, different HTS hybrid Maglev arrangements involving PM and bulk HTS were tested above the permanent magnet guideway. Some useful conclusions and reference for relative design can be found from the experimental results and analyses.

T_{\rm c}

A novel high-temperature superconducting (HTS) magnetic helix transmission mechanism is introduced to overcome the inevitable friction and wear of a traditional mechanical helix transmission mechanism. It is based on the principle that a high-temperature superconductor can move in one direction with a uniform magnetic field without any resistance. The mechanical property of this mechanism is theoretically studied. Results show that the driving torque and axial carrying capacity are closely dependent on the lead angle of the magnetic bolt.

Superconductive Hybrid Maglev System

An improved high-temperature superconducting maglev measurement system (SCML-01) was designed and successfully developed to further study the maglev properties of YBaCuO bulks above permanent magnets (PM) or a PM guideway. The system includes a liquid nitrogen vessel, a cylinder PM or PM guideway, a set of two-dimensional motion mechanisms, a set of three-dimensional motion mechanisms, control hardware, and control processing software. In addition to keeping the previous capabilities, the most recent improvements include an integrated measurement of displacement, temperature, force, torque, and magnetic field signals all with higher precision. In particular, the three-dimensional motion mechanism can combine any two-dimensional direction to realize some complicated curve movements, such as z-type, slant-type, and circle-type back and forth many times. These new functions have an important meaning for practical application.

A High-Temperature Superconducting Magnetic Helix Transmission Mechanism

The dynamic responses and levitation forces of a high temperature superconducting (HTS) maglev vehicle system were investigated through the propagation simulation of seismic waves by a horizontal vibration platform. The HTS maglev vehicle system consisted of an array of seven YBaCuO high temperature superconductor (HTSC) bulk samples suspended above a permanent magnet guideway. Excitation frequencies of 0 to 60 Hz and excitation amplitudes of 1 to 3 mm were used to measure the HTS bulks characteristics in the time domain and horizontal displacements under horizontal vibrations. Results show that lateral stability and levitation performance is correlated to the excitation amplitude and the excitation frequency at the resonance frequency 5 Hz. This in turn is helpful towards the application of HTS maglev vehicles in the future.

An Improved High-

A method to transport up to 180 A of current into the sample space of a pressure cell without causing thermal instabilities at 77 K was developed in order to study the critical current Ic of samples of first-generation Bi-2223 superconducting wire at different hydrostatic pressures. Ic was found to linearly decrease with increasing application of external pressure and was found to be irreversible upon release of pressure. The n-value of the voltage-current curves at different pressure was also found to systematically decrease. The decrease in Ic and the irreversibility effect is attributed to the deformation of the filamentary walls of the wire.

T_{\rm c}

The motivation of this paper is intended to investigate the evolving characteristics of the vertical force of a bulk high-Tc superconductor (HTSC) undergoing a durative vertical fluctuation above a permanent magnet guideway (PMG) with a 3-D finite-element model. To mathematically characterize the electromagnetic interaction of the HTSC/PMG system, the 3-D model was established by making recourse to a combination of current vector potential method and Helmholtzs theorem. The special properties of HTSC, including the anisotropic critical current density and nonlinear E-J relation, were taken into account by means of the elliptical model and power-law model respectively. The envisaged factors that may affect the vertical force of the HTSC in the case considered here, such as levitation height and amplitude of vertical fluctuation, were estimated by altering the specific shape of each factor. Numerical results demonstrate that, increasing the levitation height will result in a lower decay of the vertical force due to vertical fluctuation. In contrast, increasing the amplitude of the vertical fluctuation will deteriorate the vertical force decay. Fortunately, the levitation force decay tends to be suspended after a certain cycle of vertical fluctuation, which is in agreement with our previous experimental findings.