Study on Polishing Method Using Double Magnet System by Superconductive Assisted Machining Method

Superconductive Assisted Machining Method (SUAM) has been studied for polishing methods inside the hollow structure such as SUS tube. Levitation tool with Nd permanent magnet in the SUAM system is trapped by magnetic flux pinning effect into the superconductor bulk mounted in the liquid nitrogen box. In this case, initial displacement of the levitation tool can be adjusted until 12mm during cooling process under magnetic field. Movement of the superconductor bulk controls the applied force and rotation speed of the levitation tool. In previous research, we demonstrated that the SUAM could be applied lapping and polishing process on concave and flat shapes of the resin, aluminum and SUS materials. In present study, we develop the double magnet system that Nd permanent magnet fixed under the superconductor to increase holding force of the levitation tools. As results, holding force and levitation amount of the double magnet system increase against the conventional single magnet system. We also evaluate dominant parameters such as the placement of the superconductors and magnet flux density distribution from double permanent magnets on the holding force and levitation amount. In this case, the holding force and floating amount is calculated by JMAG using Finite Element Method to compare with the experimental results.

A Concept for Capturing and Docking Spacecraft with Flux-Pinned Interfaces

Flux-pinned interfaces for spacecraft leverage the physics of magnetic flux pinning to govern the dynamics betweenclose-proximity spacecraft. The behavior of this interface enables a magnet to be held at a distance in up to six degrees of freedom relative to a type-II superconductor without contact or active control systems. This behavior is the result of a magnetic potential well with an equilibrium set by designer of the interface. When applied to a conceptual sample capture scenario, this approach offers several unique advantages over traditional mechanical capture systems, including robustness to control failures and the ability to preferentially orient the capture target without mechanical keying features. However, as a passive system, it is important to characterize the depth and shape of the potential well in order to bound the acceptable relative motion between a notional spacecraft and a notional sample cache to ensure a successful capture. This paper presents the results of a series of air bearing experiments designed to determine these bounds. Extrapolating from the ground testing environment, it was determined that the FPI is expected to work at a range of 50 cm in orbit around Mars, and operates best in a path angle of 0 degrees. It can tolerate a total relative translational velocity of up to 4.7 cm/sec or a total angular rate of 24 deg/sec between a spacecraft and a sample cache.

Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

In this paper, we measure the attraction (suspension) and repulsion (levitation) forces produced by the interaction between a permanent magnet and different bulk superconductors. The measurements of the interaction force HTS-PM were carried out with a relatively simple technique developed by us, which is reproducible, reliable and low cost. The obtained results were analyzed with the Bean’s critical-state model assuming a uniform magnetic field applied to the superconductor. Two superconducting samples of YBa2Cu3O7-δ (YBCO) prepared by solid-state reaction method and by the melt-textured growth method (MTG) were used. Both samples presented a different hysteresis behaviour in the field cooling (FC) and zero field cooling (ZFC) regimes. Levitation and suspension phenomena were observed in the MTG sample; however, the sintered sample (S) with Oxygen deficiencies (δ > 0.15) displayed a slight levitation force but did not show a suspension force, the latter one attributed to a more efficient magnetic flux pinning. Additionally, the critical current density of both samples was determined from the maximum gap of the force (ΔF) in the FC regime. The obtained values were between 43.00 A/cm2 and 2,758 A/cm2 for the sintered and MTG samples, respectively. These values show a remarkable difference between sintered and MTG samples like that observed from magnetization measurements, which indicate that attraction and repulsion force measurements could provide a rapid and reliable characterization method of polycrystalline superconducting samples.

The effects of sintering temperature on superconductivity of MgB2 prepared by hot pressing

The [Formula: see text] superconductor bulks were prepared by hot-pressing under the pressure of 55 MPa at different temperatures of 650[Formula: see text]C, 700[Formula: see text]C, 800[Formula: see text]C, 900[Formula: see text]C, 1000[Formula: see text]C, respectively, and the hot-pressing effects on the superconducting properties of [Formula: see text] bulks were investigated. The density of bulk samples increased with the rise of sintering temperature and the density reached to the maximum value when the sintering temperature rose to 1000[Formula: see text]C. For the sample sintered at 1000[Formula: see text]C, the critical transition temperature ([Formula: see text] reached the highest value of 38.8 K despite the high content of [Formula: see text] (30.62 wt.%). However, the critical current density ([Formula: see text] did not increase with the increase in the density and [Formula: see text]. The sample sintered at 700[Formula: see text]C maintained the high superconducting volume and had a small grain size, thus providing the best magnetic flux pinning force and [Formula: see text]. An effective hot-pressing process to improve [Formula: see text] might be the way to prepare by further increasing the density of sintering samples at 700[Formula: see text]C.

Strong correlation between flux pinning and epitaxial strain in the GdBa2Cu3O7−x/La0.7Sr0.3MnO3 nanocrystalline heterostructure

The effect of magnetic flux pinning is investigated in GdBa2Cu3O7 (GdBCO) thin films with two different types of ferromagnetic La0.7Sr0.3MnO3 (LSMO) buffers (nanoparticles and a layer) deposited on an STO substrate.