Search

In this paper, a compact torus (CT) injector system is designed for experimental advanced superconducting tokamak (EAST). The injector system consists of a coaxial electrode and four pulsed power systems and generates self-organized CT with high density and velocity. In addition, the performance of EAST-CTI is evaluated using a series of diagnostics systems. The experimental results show that the velocity, electron density, and number of particles of the CT are 56.0 km/s, 8.73 × 1020 m-3, and 2.4 × 1018, respectively. The detailed description and experimental results are presented in this paper. more...

Tuning the magneto-electronic properties of graphene-based structures into distinguished performance is an interesting but challenging work. To address this issue, we here construct several chain-like 1D nanostructures by stitching zigzag-edged triangular graphene nanoflakes with different manners and subsequently oxidized at edges. The high stability of these structures is identified by the calculated edge adsorption energy, phonon spectrum, and molecular dynamics simulations. Unlike edge-hydrogenation case, termination oxygen atoms here are highly magnetized and can control such 1D chain magneto-electronic features substantially. The calculations predict that such 1D chains are very versatile, and behaviors are sensitive to geometry, likely acting as a ferromagnetic metal and half-metal and bipolar magnetic semiconductor, or an antiferromagnetic metal and semiconductor. In particular, such a ferromagnetic half-metallic feature can occur in the ground state and possesses a wide bandgap, suggesting that they are excellent magnetic materials. The calculated spin transport characteristics reveal that such a chain-based device promises not only a perfect double spin-filtering effect, but also an excellent dual spin diode feature and a giant magnetoresistance (GMR) effect. The advantages over graphene nanoribbons are thus expected. more...

Using the part exchange-coupling model, the exchange-coupling interaction between magnetically soft and hard grains in Nd2Fe14B/α-Fe nanocomposite and its effect on the effective anisotropy of the material have been investigated. By testing six different functions, series curves of effective anisotropy constant versus the mean grain size were obtained. The calculation results show that the effective anisotropy of the composite increases slightly with decreasing grain size, reaches the maximum at about 23nm, and then decreases abruptly. The calculated curves resemble the experimental results of the coercivity versus grain size in nanocomposite. more...

La0.7−xNdxBa0.3MnO3 polycrystalline samples with different Nd content were prepared by a sol–gel method. The effects of Nd addition on the Curie temperature Tc and the magnetocaloric properties were investigated. The experimental results show that the addition of Nd enhances the magnetic entropy change and adjusts the Curie temperature efficiently in polycrystalline La0.7−xNdxBa0.3MnO3. Large magnetic entropy changes upon application of a low magnetic field and a wide temperature range of Tc suggest that these materials can be utilized as magnetic refrigerants near room temperature. more...

Single-phase polycrystalline samples of La0.67Ca0.33Mn1−xO3 (x=0.00, 0.02, 0.04, 0.06) have been prepared using the sol–gel method. The structure, magnetocaloric properties and the Curie temperature of the samples with different Mn vacancy concentrations have been investigated. The experimental results show that vacancy doping at the Mn-sites has a significant influence on the magnetic properties of La0.67Ca0.33Mn1−xO3. The Curie temperature decreases monotonically with increasing the Mn-site vacancy concentration x. A remarkable enhancement of the magnetic entropy change has been obtained in the La0.67Ca0.33Mn0.98O3 sample. The entropy change reaches |ΔSM|=3.10 J kg−1 K−1 at its Curie temperature (264 K) under an applied magnetic field H=10 kOe, which is almost the same value as that of pure Gd. more...