Characteristic of the Guidance Force in the High-T c Superconducting Levitation System with Pre-Load Process

Abstract

The stable levitation above permanent magnet is an important characteristic of the bulk high-T c superconductor (HTS). When an external force pushes the bulk HTS up, down or sideways, or tries to tilt it, a restoring force can return it to its initial position. The HTS Maglev relied on this characteristic can overcome the external force from wind or pass the curve lines successfully. The change of guidance force (GF) during many times lateral movement is studied. Experiments show that GF increases during the lateral movement, no matter what kind of PMG or HTS is used, and the change of the GF slows down after 5 times lateral movement. The pre-load method can reduce the levitation force decay during lateral movement. So the influence of GF by the pre-load method is needed to be studied. It is found that the pre-load method can increase GF and reduce the change of the GF during lateral movement. The Halbach permanent magnetic guideway (PMG) can offer much more GF but the change is larger just as the levitation force decays. The GF of cylindrical bulk HTS increases more than of the rectangular bulk HTS in the pre-load case. The characteristics of the GF during the lateral movement are explained. These results are important for further HTS Maglev vehicle system designs.

Dynamic guidance performance of GdBaCuO and YBaCuO bulk single grain superconductors under a varying external magnetic field

“…The guidance force also increases to its maximum value at the lateral displacement (LD). The guidance force F x of the HTS bulk single grain can be described by equation (1) [18].…”

“…where J is the current density of the HTS bulk single grain, B y is the vertical component of the applied external field and dV is the volume of the HTS bulk sample. J z is determined by dB/dy [18]. The HTS single grain exhibits a unique magnetic flux capture characteristic during the LD process, increasing the measured guidance force.…”

“…The ability of the HTS vehicle to negotiate curves is determined critically by the guidance performance of the HTS bulks [18]. Wang et al studied the guidance force of the 'Century' manned HTS vehicle under different quasi-static operating conditions [19].…”

Dynamic guidance performance of HTS bulk under varying external magnetic field

“…The guidance force also increases to the maximum (F A ) at the MLD. The variation of the guidance force can be theoretically explained by [15]:…”

“…In 2000, the world's first manloading high speed HTS Maglev vehicle 'Century' was successfully developed at Southwest Jiaotong University in China [1]. Successively, many countries have also developed HTS It is well known that the guidance performance of the bulk superconductor is closely related to the curve negotiation ability of the HTS maglev [15]. Many researchers have done experimental works on quasi-static guidance forces to promote the development of HTS maglev.…”