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Introduction
Published in Shoogo Ueno, Tsukasa Shigemitsu, Bioelectromagnetism, 2022
Shoogo Ueno, Tsukasa Shigemitsu
When a resistor is connected to one end of a wire and an electric current flows through the wire, the current creates magnetic lines of force around the wire. Magnetic lines of force are also invisible, but when a magnet is placed near the wire, its existence is confirmed by the experience of attractive or repulsive forces in the direction of the magnetic lines of force. The space where these magnetic lines of force exist or the field where they act is called magnetic fields. Its strength is proportional to the density of the magnetic lines of force. Even if an AC power supply is used instead of a DC power supply, the distribution pattern remains the same as in the case of a DC power supply, except that the direction of the magnetic lines of force reverses corresponding to the direction of the current. The units of magnetic field strength are Newton/Weber (N/Wb) and Ampere/Meter (A/m). Magnetic flux density, which is defined as the amount of magnetic field passing through a unit cross-section area, is used in place of magnetic field. The unit for magnetic flux density is Wb/m or Tesla (T) which is equal to 104 Gauss (G). If H and B are made to be the magnetic field and the magnetic flux density, respectively, it becomes B=μH
Fusion Energy
Published in Geoffrey F. Hewitt, John G. Collier, Introduction to Nuclear Power, 2018
Geoffrey F. Hewitt, John G. Collier
Most effort is therefore being devoted to trying to achieve a fusion reaction using magnetic confinement. The structure of magnetic fields is often indicated by lines of force or field lines the stronger the field, the greater the density of the lines. Within a magnetic field, charged nuclei take a spiral path in the direction of the field lines as illustrated in Figure 9.5a. A magnetic field line causes a charged nudeus to spiral around it (Figure 9.5a). If the field is arranged so as to dose on itself in a circle within a circular chamber (Figure 9.5b), the particles will spiral around the field and remain trapped within the circular chamber, or torus. Unfortunately, this does not always happen in practice due to instabilities that occur in the plasma. Nevertheless, most of the experiments that have tried to achieve controlled fusion reactions make use of this dosed doughnut-shape configuration. Another possibility is to constrict the magnetic field lines at each end of a tube. Particles trying to escape by spiraling along the field lines are reflected back into the central region. This arrangement is called a magnetic mirror or bottle (Figure 9.5c).
Magnetism
Published in Joe Cieszynski, David Fox, Electronics for Service Engineers, 2012
It was Faraday who suggested that the magnetic field around the magnet was made up of lines of force. The strength of the magnet being determined by the closeness of the lines of force. The properties of lines of force are always the same in any magnetic field. They are as follows: Lines of force are continuous.Lines of force do not cross.Lines of force travel from north to south.Lines of force travelling parallel to each other tend to move apart.Lines of force travelling towards each other are in opposition and therefore diverge.Lines of force contract (act similar to an elastic band).
Theoretical Analysis of Magnetic Pinch Glow Discharge Plasma at Low Pressure
Published in Fusion Science and Technology, 2022
In the process of discharge, electrons move from the cathode to the anode. The introduction of magnetic field limits the trajectory of electrons and makes them move around the magnetic line of force. Under the condition of a weak magnetic field, the cyclotron radius of electrons is large, which increases the average free path of the electrons, improves the collision probability between the electrons and the neutral atoms, and increases the plasma density. Under the condition of a strong magnetic field, the gyration radius of electrons is very small, and the kinetic energy obtained by electrons in the process of moving from the cathode to the anode is less, which reduces the probability of collision ionization between electrons and neutral atoms, and the plasma density decreases. At low pressure, the distance between neutral molecules is large, and the introduction of the magnetic field further limits the moving range of electrons and reduces the probability of collision between electrons and neutral atoms. Therefore, the plasma density decreases with the increase of the magnetic field.
Magnetohydrodynamic flow and Hall current effects on a boundary layer flow and heat transfer over a three-dimensional stretching surface
Published in International Journal of Ambient Energy, 2023
M. Ferdows, G. K. Ramesh, J. K. Madhukesh
Magnetohydrodynamics is a continuum mechanics branch that studies the flow of an electrically conducting liquid in the existence of a magnetic field. The investigation of the magnetohydrodynamic (MHD) flow of an electrically conducting fluid caused by a stretched surface is critical in present metallurgy and metal-working techniques. The movement of conducting material between magnetic lines of force generates potential differences, which in turn cause electric currents to flow. The magnetic fields associated with these currents alter the magnetic field that generates them. The study of MHD flow has become essential in engineering applications such as building liquid metal cooling systems, MHD micro-pumps concerning drug delivery, MHD generators, and other petroleum industry equipment. Madhukesh et al. (2022b) investigated the effect of magnetic dipoles on Maxwell hybrid nano liquid flow across a stretched sheet. Habib et al. (2022) studied MHD micropolar nano-liquid movement in the presence of extending surface by considering bioconvection. The study reveals that improved values of magnetic parameter decline velocity. Madhukesh et al. (2022c) investigated the flow of hydromagnetic micropolar-Casson nanofluid past porous disks affected by Cattaneo-Christof theory and slip Implications. MHD stagnation point flow and heat transfer owing to nanofluid towards a stretched sheet was given by Ibrahim, Shankar, and Nandeppanavar (2013, 5). Subhas Abel, Tawade, and Nandeppanavar (2012, 390) investigated the upper-convected Maxwell fluid’s MHD flow and heat transfer across a stretched sheet. Its main objective was to study the impact of several physical parameters on the temperature field above the sheet. Some of the noticeable works on the concept of MHD are Ali et al. (2022a, 77, 2022b, 77), Wang et al. (2021, 11), Yusuf, Adesanya, and Gbadeyan (2020, 49, 2022), Mabood, Yusuf, and Sarris (2020).