Preface
Levitation or suspension is a phenomenon that an object occupies a fixed position
in a gravitational field without any direct physical contact. Scientists have found
and suggested a number of suspension methods, for example aerodynamic, acou-
stic, optical, electric, magnetic, and radio-frequency (RF) suspension. The levitation
phenomenon attracted not only wide attention of the public, but also the interest of
scientists and engineers. Magnetic levitation (Maglev) is a promising one in various
suspension phenomena, and it is implemented using the principle of independent
suspension with magnetic field. Maglev technologies have a series of potential ad-
vantages including high or ultra high speed, low energy consumption, environment
friendly, low maintenance, moderate footprint, low operating costs, etc. Maglev is
currently attracting worldwide interest for both high-speed intercity vehicles and low-
speed urban transit vehicles, especially high- or ultra-high-speed intercity traffic.
After nearly a century long development, Maglev finally began to penetrate ground
transportation markets and presented the possibility of rapid development. Traditio-
nal and superconducting Maglev have different characteristics. The high-temperature
superconducting (HTS) bulk Maglev can realize stable levitation without any active
control. The physical characteristics of self-stabilization of HTS bulk Maglev is a
unique phenomenon in nature. This is especially attractive for practical applications
of Maglev transportation. Experts worldwide are trying to complete the HTS Maglev
vehicle test. This book is devoted to HTS Maglev. Fundamentals of superconductivity
are introduced in Chapter 1. Superconductivity is a deep and complex subject. We
can only provide a brief overview about basic superconductivity in this book, which
is required to understand how HTS Maglev works. In Chapter 2, we discuss the
superconducting materials. After a brief introduction of superconducting materials,
we will focus on the HTS bulk and its thermal, mechanical, and trapped flux pro-
perties, which are all essential in HTS Maglev applications. Magnetic levitation will
be discussed in Chapter 3. To help the reader understand Maglev transportation, we
start with the value of the ground track-based traffic system and the limitations of
the traditional railway transport, then move on to levitation phenomenon, magnetic
levitation concepts, and non-superconducting magnetic levitation applications like
the permanent magnet Maglev and normal conductive Maglev. In addition to the
advantages of permanent magnet and normal conductive Maglev, superconducting
Maglev gains further improvement including more energy-saving, environmental
protection, high speed, and most important, the possibility of ultra high speed. The
superconducting Maglev, LTS and HTS Maglev, will be discussed in Chapter 4. Various
types of Maglev have different performance. In the constant pursuit of the “perfect”
Maglev transportation, the new HTS Maglev train stands out to be one of the best
candidates. With the previous Maglev testing method, the YBCO bulk is placed in a
simple liquid nitrogen container which is below the permanent magnet. Other than