Low frequency rotational loss in a high-temperature superconducting bearing and its application in micro-thrust measurement for space propulsion

Abstract

High-temperature superconducting (HTS) magnetic bearings have great potential in the field of rotating machinery, such as flywheels and momentum wheels, because of their low friction and self-stabilizing capability. The study of rotational loss in HTS bearing is of great significance to achieve better efficiency. Previous research indicates that low rotational loss has a close relation with hysteresis loss in HTSs and eddy-current losses in the surrounding metal materials. A low coefficient of friction (<10 −8 ) at low speed is attractive for high precision instruments. This paper first presents a short overview of low rotational loss in HTS bearings, and then a special design of HTS bearing is given for application in micro-thrust measurements of space propulsion. The load capacity of the bearing allows for up to 10 kg, which means that the entire thruster system can be suspended to avoid measuring the internal force. Two different measuring methods are designed to fit several operational modes of the micro-thruster, and the measured thrust level is from 1 mN to 100 mN. The bearing system shows great response to short pulse modes of the micro-thruster, and an impulse of 1 mN•s was identified accurately. The measured thrust shows great agreement with the designed values of the micro-thruster, indicating the effective application of the HTS bearing for micro-thrust measurements.

Flux jumps in ring-shaped and assembled bulk superconductors during pulsed field magnetization

“…Durrell et al reported a trapped field of 17.6 T at the centre of a stack of two GdBa 2 Cu 3 O 7−δ (GdBCO) bulk superconductors at 26 K, with 17.24 T having been achieved previously in an equivalent arrangement of YBa 2 Cu 3 O 7−δ (YBCO) [1,2]. Ring-shaped (annular) bulk superconductors that enable access to these large magnetic fields have been investigated for various applications, such as compact nuclear magnetic resonance [3][4][5][6][7][8][9][10] and for more general applications [11][12][13][14]. However, in situ magnetization on these materials remains a significant challenge and a barrier to practical applications of these technologically important materials.…”

Loading capacity, rotation loss and torsional oscillation research on an Evershed-type hybrid superconducting bearing used for micro-thrust measurements

“…Benefiting from self-stable suspension and moderate stiffness in the radial and axial directions, bulk high-temperature superconductors (HTS) have many engineering applications, such as maglev trains [1,2], superconducting bearings [3,4], flywheel energy storage (FES) systems [5,6] and high-resolution devices [7,8]. In addition, extensive advances have been made in understanding and reducing rotational losses in HTS magnetic bearings, especially for application in FES systems with a high rotation speed [9,10].…”

“…Due to their very low rotational drag, applications of HTS bearings have been expanded in some high-precision instruments including accelerometers [15], lunar telescopes [16], sensitive gravimeters [17], polarimeters [18] and micro-force sensing devices [7,10]. The use of HTS magnetic bearings in building a micro-thrust test stand is a relatively new application.…”

Translational levitation of a permanent magnet above the splicing plane of superconducting blocks under zero field cooling and its motion drag

“…These maglev systems have high load capacity and low motion drag, and the friction coefficient of levitation can almost reach 10 -7 . Low drag and low energy consumption also take it valuable application in high precision instruments [8][9][10]. However, flux pinning provides these HTS systems self-stability, but also limits their degrees of freedom at the same time, thus most of them only can rotate or oscillate in one dimension [11].…”