Exploring extreme magnetization phenomena in directly-driven imploding cylindrical targets

This paper uses extended-magnetohydrodynamics (MHD) simulations to explore an extreme magnetized plasma regime realisable by cylindrical implosions on the OMEGA laser facility. This regime is characterized by highly compressed magnetic fields (greater than 10kT across the fuel), which contain a significant proportion of the implosion energy and induce large electrical currents in the plasma. Parameters governing the different magnetization processes such as Ohmic dissipation and suppression of instabilities by magnetic tension are presented, allowing for optimization of experiments to study specific phenomena. For instance, a dopant added to the target gas-fill can enhance magnetic flux compression while enabling spectroscopic diagnosis of the imploding core. In particular, the use of Ar K-shell spectroscopy is investigated by performing detailed non-LTE atomic kinetics and radiative transfer calculations on the MHD data. Direct measurement of the core electron density and temperature would be possible, allowing for both the impact of magnetization on the final temperature and thermal pressure to be obtained. By assuming the magnetic field is frozen into the plasma motion, which is shown to be a good approximation for highly magnetized implosions, spectroscopic diagnosis could be used to estimate which magnetization processes are ruling the implosion dynamics; for example, a relation is given for inferring whether thermally-driven or current-driven transport is dominating.

EFFECT OF MAGNETIC FIELD ON THE PHYSICAL AND CHEMICAL PROPERTIES OF FLOWING LUBRICATING COOLING LIQUIDS USED IN THE MANUFACTURING PROCESS

In this paper, the effect of magnetic field on lubricating cooling liquids, which are used in the cutting process in manufacturing, was studied. We chose three different lubricating cooling liquids that are commonly used in local manufacturing factories to conduct the experiment. Three main properties of these lubricoolants, boiling point, kinematic viscosity, and density, were analysed after magnetizing them. The magnetization processes were conducted in two conditions of liquids. At the first stage, the authors magnetized the liquids in stationary conditions; at the second stage, they magnetized the flowing liquids and analysed the difference among all the obtained results. This article shows the results of the comparisons and analyses the magnetic field influence on different types of fluids. Moreover, the paper investigates the dependence of magnetic field strength on the influence of magnetic field on liquids. It was found that the examined three parameters of liquids were changed after magnetic field treatment. The finding of this research offered a simple approach to improve the lubricating and cooling process in machining details in manufacturing. ABSTRAK: Dalam makalah ini, pengaruh medan magnet pada cecair pendingin pelincir, yang digunakan dalam proses pemotongan dalam pembuatan, telah dikaji. Kami memilih tiga cecair penyejuk pelincir berbeza yang biasa digunakan di kilang pembuatan tempatan untuk menjalankan eksperimen. Tiga sifat utama pelincir ini seperti takat didih, kelikatan kinematik, dan ketumpatan dianalisis setelah memagnetkannya. Proses pembesaran dilakukan dalam dua keadaan cecair. Pada peringkat pertama, kami memagnetkan cecair dalam keadaan pegun dan membandingkan hasilnya; pada peringkat kedua, kami memagnetkan cecair semasa mengalir dan menganalisis perbezaan antara hasil yang diperoleh. Artikel menunjukkan hasil perbandingan ini dan menganalisis pengaruh medan magnet pada pelbagai jenis cecair. Lebih-lebih lagi, makalah ini meneliti pergantungan kekuatan medan magnet terhadap pengaruh medan magnet pada cecair. Didapati bahawa tiga parameter cecair yang diperiksa diubah setelah rawatan medan magnet. Penemuan penyelidikan ini menawarkan pendekatan mudah untuk meningkatkan proses pelinciran dan penyejukan dalam perincian mesin dalam pembuatan.

Influence of Dissolving Fe–Nb–B–Dy Alloys in Zirconium on Phase Structure, Microstructure and Magnetic Properties

This paper refers to the structural and magnetic properties of [(Fe80Nb6B14)0.88Dy0.12]1−xZrx (x = 0; 0.01; 0.02; 0.05; 0.1; 0.2; 0.3; 0.5) alloys obtained by the vacuum mold suction casting method. The analysis of the phase contribution indicated a change in the compositions of the alloys. For x < 0.05, occurrence of the dominant Dy2Fe14B phase was observed, while a further increase in the Zr content led to the increasing contribution of the Fe–Zr compounds and, simultaneously, separation of crystalline Dy. The dilution of (Fe80Nb6B14)0.88Dy0.12 in Zr strongly influenced the magnetization processes of the examined alloys. Generally, with the increasing x parameter, we observed a decrease in coercivity; however, the unexpected increase in magnetic saturation and remanence for x = 0.2 and x = 0.3 was shown and discussed.

Magnetic reversal modes in cylindrical nanostructures: from disks to wires

Cylindrical magnetic nanowires are key elements of fast-recording and high-density 3D-storage devices. The accurate tuning of the magnetization processes at the nanoscale is crucial for the development of future nano-devices. Here, we analyzed the magnetization of Ni nanostructures with 15–100 nm in diameter and 12–230 nm in length and compared our results with experimental data for periodic arrays. Our modelling led to a phase diagram of the reversal modes where the presence of a critical diameter (d ≈ 30 nm) triggered the type of domain wall (DW) formed (transverse or vortex); while a critical length (L ≈ 100 nm) determined the number of DWs nucleated. Moreover, vortex-DWs originated from 3D skyrmion tubes, reported as one of the best configurations for storage devices. By increasing the diameter and aspect-ratio of nanowires with L > 100 nm, three reversal modes were observed: simultaneous propagation of two vortex-DWs; propagation of one vortex-DW; or spiral rotation of both DWs through “corkscrew” mechanism. Only for very low aspect-ratios (nanodisks), no skyrmion tubes were observed and reversal occurred by spiral rotation of one vortex-DW. The broad range of nanostructures studied allowed the creation of a complete phase diagram, highly important for future choice of nanoscaled dimensions in the development of novel nano-devices.