Jiasu Wang

The first man-loading high temperature superconducting Maglev test vehicle in the world

The first man-loading high temperature superconducting Maglev test vehicle in the world is reported. This vehicle was first tested successfully on December 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 17,000 passengers took the vehicle, and it operates very well from beginning to now. The function of suspension is separated from one of propulsion. The high temperature superconducting Maglev provides inherent stable forces both in the levitation and in the guidance direction. The vehicle is 3.5 m long, 1.2 m wide, and 0.8 m high. When five people stand on vehicle and the total weight is 530 kg, the net levitation gap is more than 20 mm. The whole vehicle system includes three parts, vehicle body, guideway and controlling system. The high temperature superconducting Maglev equipment on board is the most important for the system. The onboard superconductors are melt-textured YBaCuO bulks. The superconductors are fixed on the bottom of liquid nitrogen vessels and cooled by liquid nitrogen. The guideway consists of two parallel permanent magnetic tracks, whose surface concentrating magnetic field is up to 1.2 T. The guideway is 15.5 m long.

An Update High-Temperature Superconducting Maglev Measurement System

An update high temperature superconducting Maglev measurement system (SCML-02) was successfully developed. The system includes liquid nitrogen vessel, cylinder permanent magnet (PM) or PM guideway (PMG), data collection and processing, mechanical drive and autocontrol. The liquid nitrogen vessel with high temperature superconductors (HTSCs) can be placed above or under the PM. This measurement system has other characteristics: high measurement precision, instant measurement at movement of the measured HTSCs specimen, synchronous measurement of levitation and guidance, measurement in three dimensions at one time, relaxation measurement of both levitation and guidance force, and so on. In order to calibrate measurement precision and to verify special function of SCML-02, two cylinder PMs are used, which have the same scale and technical specification. The Maglev properties of HTSCs YBCO bulk are measured on the basis of the calibration results of SCML-02. The levitation forces of single YBCO bulk and of seven YBCO bulks above PMG are measured by SCML-02. All functions are validated experimentally. The main specification of the measurement system is: position precision plusmn 0.05 mm; vertical force precision 2%c; horizontal force precision 1%c. The force measurement precision has achieved 0.02 N

Superconductivity and the environment: a Roadmap

There is universal agreement between the United Nations and governments from the richest to the poorest nations that humanity faces unprecedented global challenges relating to sustainable energy, clean water, low-emission transportation, coping with climate change and natural disasters, and reclaiming use of land. We have invited researchers from a range of eclectic research areas to provide a Roadmap of how superconducting technologies could address these major challenges confronting humanity.Superconductivity has, over the century since its discovery by Kamerlingh Onnes in 1911, promised to provide solutions to many challenges. So far, most superconducting technologies are esoteric systems that are used in laboratories and hospitals. Large science projects have long appreciated the ability of superconductivity to efficiently create high magnetic fields that are otherwise very costly to achieve with ordinary materials. The most successful applications outside of large science are high-field magnets for magnetic resonance imaging, laboratory magnetometers for mineral and materials characterization, filters for mobile communications, and magnetoencephalography for understanding the human brain.The stage is now set for superconductivity to make more general contributions. Humanity uses practically unthinkable amounts of energy to drive our modern way of life. Overall, global power usage has been predicted to almost double from 16.5 to 30?TW in the next four decades (2011 Equinox Summit: Energy 2030 http://wgsi.org/publications-resources).The economy with which electrons carry energy compels the continued quest for efficient superconducting power generation, energy storage, and power transmission. The growing global population requires new arable land and treatment of water, especially in remote areas, and superconductivity offers unique solutions to these problems. Exquisite detectors give warning of changes that are otherwise invisible. Prediction of climate and disasters will be helped by future supercomputer technologies that support huge amounts of data and sophisticated modeling, and with the aid of superconductivity these systems might not require the energy of a large city.We present different sections on applications that could address (or are addressing) a range of environmental issues. The Roadmap covers water purification, power distribution and storage, low-environmental impact transport, environmental sensing (particularly for the removal of unexploded munitions), monitoring the Earth?s magnetic fields for earthquakes and major solar activity, and, finally, developing a petaflop supercomputer that only requires 3% of the current supercomputer power provision while being 50 times faster.Access to fresh water. With only 2.5% of the water on Earth being fresh and climate change modeling forecasting that many areas will become drier, the ability to recycle water and achieve compact water recycling systems for sewage or ground water treatment is critical. The first section (by Nishijima) points to the potential of superconducting magnetic separation to enable water recycling and reuse.Energy. The Equinox Summit held in Waterloo Canada 2011?(2011 Equinox Summit: Energy 2030 http://wgsi.org/publications-resources) identified electricity use as humanity?s largest contributor to greenhouse gas emissions. Our appetite for electricity is growing faster than for any other form of energy. The communiqu? from the summit said ?Transforming the ways we generate, distribute and store electricity is among the most pressing challenges facing society today?. If we want to stabilize CO2 levels in our atmosphere at 550 parts per million, all of that growth needs to be met by non-carbon forms of energy? (2011 Equinox Summit: Energy 2030 http://wgsi.org/publications-resources). Superconducting technologies can provide the energy efficiencies to achieve, in the European Union alone, 33?65% of the required reduction in greenhouse gas emissions according to the Kyoto Protocol (Hartikainen et?al 2003 Supercond. Sci. Technol. 16 963). New technologies would include superconducting energy storage systems to effectively store power generation from renewable sources as well as high-temperature superconducting systems used in generators, transformers and synchronous motors in power stations and heavy-industry facilities. However, to be effective, these systems must be superior to conventional systems and, in reality, market penetration will occur as existing electrical machinery is written off. At current write-off rates, to achieve a 50% transfer to superconducting systems will take 20?years (Hartikainen et?al 2003 Supercond. Sci. Technol. 16 963).The Roadmap next considers dc transmission of green power with a section by Eckroad and Marian who provide an update on the development of superconducting power transmission lines in view of recent sustainability studies. The potential of magnetic energy storage is then presented by Coi and Kim, who argue that a successful transition to wind and solar power generation must be harmonized with the conventional electrical network, which requires a storage technology with a fast response and long backup times.Transport. Superconducting Maglev trains and motors for international shipping have the potential to considerably reduce the emissions that contribute to greenhouse gases while improving their economic viability by reducing losses and improving efficiencies. International shipping, alone, contributes 3% of the greenhouse gas emissions. Three sections of the Roadmap identify how high-speed rail can be a major solution to providing fast, low energy, environmentally-friendly transport enabling reduction in automobile and aircraft travel by offering an alternative that is very competitive. With maritime international environmental regulations tightening, HTS motors with the characteristics of high torque and compactness will become important devices for high-performance and low-emission electric ship propulsion systems. A section on the development of a megawatt-class superconducting motor for ship propulsion is presented by Umemoto.Monitoring in manufacturing for waste reduction. Environmental impact from the waste created by the manufacturing sector and the need to make manufacturing efficient can be addressed by terahertz imaging. This technology has great potential in non-destructive testing, industrial process monitoring and control to greatly improve the industry process efficiency and reliability by reducing waste materials and toxic by-products. The section by Du shows how terahertz imaging can provide process and property information such as rust levels under paint that can assist with the reduction of waste in manufacturing and maintenance.Monitoring for naturally occurring disturbances. The environmental and social impact of natural disasters is mounting. Febvre provides the Roadmap for the use of ultra-sensitive magnetometry to understand geomagnetic phenomena and Earth?ionosphere couplings through the study of very small variations of the magnetic field. This magnetic monitoring has many implications for understanding our environment and providing new tools for early warning of natural hazards, either on Earth or in space which will enable us to be better prepared for natural disasters.Restoring environments after military use. Throughout the world, there are many areas confirmed or suspected of being contaminated by unexploded munitions known as unexploded ordnance (UXO). Its presence is the result of wars and training of military forces. Areas affected by UXO contamination are hazardous to the public and have a major influence on the nature of land use. UXO has impact in developed as well as developing nations. For example, the USA has UXO dating back to the American Civil War and countries such as Cambodia are living with landmines as a daily issue due to more recent wars. Underwater UXO has caused severe impacts such as the explosion in 1969 in the waters of Kent in the UK that caused a reading of 4.5 on the Richter scale for earthquake monitors. Another example was a land-based detonation of a 500?kg World War II bomb in Germany killing three people in 2010. There is countless UXO from recent conflicts worldwide. Detection and accurate location with 100% reliability is required to return land to safe civilian use. Keenan provides details of a prototype magnetic gradiometer developed for this purpose.Reducing power needs for high-end IT. Supercomputers are so large that they are close to requiring their own small power plant to support the energy needed to run the computer. For example, in 2011 Facebook data centers and operations used 532 million kW hours of energy. Mukhanov explores the potential of reducing the power dissipation for future supercomputers from more than 500?MW for Exascale systems to 0.2?MW by using superconducting-ferromagnetic Josephson junctions for magnetic memory and programmable logic.Clearly superconductivity is an ultimate energy-saving technology, and its practical implementation will contribute to the reduction of CO2 emissions, improved water purification, reduction of waste and timely preparedness for natural disasters or significant events. This Roadmap shows how the application of superconducting technologies will have a significant impact when they are adopted.

The man-loading high-temperature superconducting Maglev test vehicle

The first man-loading high-temperature superconducting (HTS) Maglev test vehicle in the world was successfully developed on Dec. 31, 2000 in the Applied Superconductivity Laboratory, Southwest Jiaotong University, China. Heretofore over 24 500 passengers took the vehicle, and it has been operating back and forth for about 400 km. The HTS Maglev vehicle provides inherent stability both in the vertical and lateral direction, so no control system is needed. The only control system is used for linear motor driving devices. The melt-textured YBaCuO bulk superconductors are fixed on the bottom of a liquid nitrogen vessel and cooled by liquid nitrogen. The bottom thickness of the rectangle liquid nitrogen vessel with its thin wall is only 3 mm. The onboard HTS Maglev module is placed over the guideway. The guideway consists of two parallel permanent magnetic tracks, whose concentrating magnetic field at 20 mm height above the surface is about 0.5 T. The levitation forces of 8 HTS Maglev modules were measured. The total levitation force of 8 onboard Maglev modules was 10431 N at the levitation gap of 10 mm, and 8486 N at the levitation gap of 15 mm, respectively. These results were measured on May 28, 2002.

Levitation force of a YBaCuO bulk high temperature superconductor over a NdFeB guideway

One of the prospective applications of YBaCuO bulk high temperature superconductors (HTS) is for superconducting magnetic levitation (Maglev) vehicles. The levitation force of a single permanent magnet over a single superconducting YBaCuO bulk has been researched, but this is not enough for practical Maglev vehicles. In this paper, properties of the levitation force of a YBaCuO bulk HTS over a NdFeB guideway are investigated. The magnetic field at the guideway surface is up to 1.2 T. During the experiment, bulk YBaCuO is placed in a columnar liquid nitrogen vessel, whose bottom thickness is only 3.5 mm, and it is over the guideway. The YBaCuO is cooled in a zero magnetic field with liquid nitrogen and can move up and down at different velocities. The measurement process is fully controlled by a computer. In this case, there is a 103.4 N levitation force at a 5 mm gap between the YBaCuO (diameter=30 mm, thickness=14 mm) sample and the NdFeB guideway. In addition, the authors compare the levitation force over the NdFeB guideway with that over a single cylindrical NdFeB permanent magnet.

Method to reduce levitation force decay of the bulk HTSC above the NdFeB guideway due to lateral movement

A magnetic levitation vehicle using bulk high-Tc superconductors (HTSC) is considered as a promising transportation type thanks to its lateral inherent stability, but previous studies have found that the levitation force (LF) decays due to lateral movement. In this paper, a pre-load method is presented to reduce the LF decay, and the experimental results indicate that this method is very applicable in supressing this decay in spite of the applied field and material property of the bulk HTSC, and this effect can be ascribed to the reduction of the hysteresis loss in the bulk HTSC, i.e. more trapped magnetic flux after the pre-load case. In the end, experimental results indicate that the Halbach PMG has an advantage to reduce the cost of the PMG, but its rate of LF decay is also larger due to lateral movement

Free Vibration of the High Temperature Superconducting Maglev Vehicle Model

Free vibration of the high temperature superconducting (HTS) Maglev vehicle model has been investigated after an impulse force over the permanent magnet guideway. The impulse force was used to simulate the external disturbances on the HTS Maglev vehicle so as to study its vibration characteristics. In the experiments, the free vibration curves of time dependence of acceleration and frequency dependence of displacement were measured. It was found that the free vibration curves were some damped free vibration curves which seemed to decrease exponentially. Applying the impulse response curves to the dynamic equation of the HTS Maglev vehicle model, the stiffness and the damping coefficient were evaluated. The relationships between field cooling height (FCH) and the stiffness and damping coefficient were investigated. A 30 mm FCH has been proposed for the good dynamic stiffness and damping coefficient so that the unnecessary vibration of the HTS Maglev vehicle model can be eliminated automatically. The dynamic results are helpful to the further design of the HTS Maglev transport system for high-speed application.

Stability of the Maglev Vehicle Model Using Bulk High Tc Superconductors at Low Speed

Based on the study of static properties of the high temperature superconducting (HTS) Maglev vehicle, the dynamic characteristics and stability are investigated in the paper. A Maglev vehicle model using 86 bulk high Tc superconductors (HTSCs) is made at 1/4 scale of the first man-loading HTS Maglev test vehicle. Dynamic characteristics of the low-speed HTS vehicle in three directions are studied by measuring vibration signals of six essential point of the vehicle model. The natural frequency is analysed. 30 mm height is suggested as a reasonable field cooling height (FCH). Lower FCH brings the operation stability of the HTS Maglev system over permanent magnetic guideway (PMG) at low speed. Dynamic stability dependence on the speed of the HTS vehicle is quite different from that of the conventional Maglev vehicle system. The effect of speed on the unsafe motions can be suppressed by decreasing FCH in the operation of the vehicle model over the PMG to a great extent.

Guidance force in an infinitely long superconductor and permanent magnetic guideway system

Guidance force is calculated when a high-temperature superconductor moves laterally on a permanent magnetic guideway. Both the superconductor and the guideway are infinitely long. The dependence of guidance performance upon both geometrical parameters, such as the shape of the superconductor and the guideway, and intrinsic parameters, such as critical current density of the superconductor and uniform magnetization of the guideway, are studied. The results may be helpful to the design and optimization of the superconducting magnetically levitated train system.

Levitation force of multi-block YBaCuO bulk high temperature superconductors

Experimental results of levitation force of multi-block YBaCuO hulk HTSs over a NdFeB guideway are presented. The magnetic field in the center of the surface of the NdFeB permanent magnet guideway is up to 1.2 T and still 0.4 T at the position of 20 mm above it. Several YBaCuO bulk samples are fixed in a columnar liquid nitrogen vessel with a thin bottom (3.5 mm). The experimental results show that the levitation force is quite different for various combinations of YBaCuO bulks. The otal combination magnetic levitation force of seven blocks of YBaCuO bulk superconductors is 264.1 N when the gap between the YBaCuO HTS and the NdFeB guideway is 10 mm, and levitation force is 167.5 N at 20 mm. Levitation force is even 106.2 N at 30 mm. The optimization of the levitation force of multi-block YBaCuO bulk superconductors is discussed after the authors analyze the experimental data.