Numerical study of electron acceleration by plasma wave in an ion channel under obliquely applied magnetic field

AbstractIn this paper, we have investigated the relativistic electron acceleration by plasma wave in an axially magnetized plasma by considering the self-magnetic field effects. We show that the optimum value of an external axial magnetic field could increase the electron energy gain more than 40% than that obtained in the absence of the magnetic field. Moreover, results demonstrate that the self-magnetic field produced by the electric current of the energetic electrons plays a significant role in the plasma wakefield acceleration of electron. In this regard, it will be shown that taking into account the self-magnetic field can increase the electron energy gain up to 36% for the case with self-magnetic field amplitude Ωs = 0.3 and even up to higher energies for the systems containing stronger self-magnetic field. The effects of plasma wave amplitude and phase, the ion channel field magnitude, and the electron initial kinetic energy on the acceleration of relativistic electron have also been investigated. A scaling law for the optimization of the electron energy is eventually proposed.

Download Full-text

Generation of Reverse Meniscus Flow by Applying An Electromagnetic Brake

Metallurgical and Materials Transactions B ◽

10.1007/s11663-021-02247-x ◽

2021 ◽

Author(s):

Alexander Vakhrushev ◽

Abdellah Kharicha ◽

Ebrahim Karimi-Sibaki ◽

Menghuai Wu ◽

Andreas Ludwig ◽

...

Keyword(s):

Magnetic Field ◽

Lorentz Force ◽

Applied Magnetic Field ◽

Numerical Study ◽

Flow Direction ◽

Experimental Studies ◽

Submerged Entry Nozzle ◽

Mean Flow ◽

Slab Caster ◽

The Mean

AbstractA numerical study is presented that deals with the flow in the mold of a continuous slab caster under the influence of a DC magnetic field (electromagnetic brakes (EMBrs)). The arrangement and geometry investigated here is based on a series of previous experimental studies carried out at the mini-LIMMCAST facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The magnetic field models a ruler-type EMBr and is installed in the region of the ports of the submerged entry nozzle (SEN). The current article considers magnet field strengths up to 441 mT, corresponding to a Hartmann number of about 600, and takes the electrical conductivity of the solidified shell into account. The numerical model of the turbulent flow under the applied magnetic field is implemented using the open-source CFD package OpenFOAM®. Our numerical results reveal that a growing magnitude of the applied magnetic field may cause a reversal of the flow direction at the meniscus surface, which is related the formation of a “multiroll” flow pattern in the mold. This phenomenon can be explained as a classical magnetohydrodynamics (MHD) effect: (1) the closure of the induced electric current results not primarily in a braking Lorentz force inside the jet but in an acceleration in regions of previously weak velocities, which initiates the formation of an opposite vortex (OV) close to the mean jet; (2) this vortex develops in size at the expense of the main vortex until it reaches the meniscus surface, where it becomes clearly visible. We also show that an acceleration of the meniscus flow must be expected when the applied magnetic field is smaller than a critical value. This acceleration is due to the transfer of kinetic energy from smaller turbulent structures into the mean flow. A further increase in the EMBr intensity leads to the expected damping of the mean flow and, consequently, to a reduction in the size of the upper roll. These investigations show that the Lorentz force cannot be reduced to a simple damping effect; depending on the field strength, its action is found to be topologically complex.

Download Full-text

Electron acceleration in a plasma filled rectangular waveguide under obliquely applied magnetic field

Journal of Plasma Physics ◽

10.1017/s0022377806005435 ◽

2006 ◽

Vol 72 (06) ◽

pp. 983 ◽

Cited By ~ 18

Author(s):

SANDEEP KUMAR ◽

HITENDRA K. MALIK

Keyword(s):

Magnetic Field ◽

Applied Magnetic Field ◽

Rectangular Waveguide ◽

Electron Acceleration

Download Full-text

Numerical study of convection in the horizontal Bridgman configuration under the action of a constant magnetic field. Part 2. Three-dimensional flow

Journal of Fluid Mechanics ◽

10.1017/s002211209600420x ◽

1997 ◽

Vol 333 ◽

pp. 57-83 ◽

Cited By ~ 74

Author(s):

HAMDA BEN HADID ◽

DANIEL HENRY

Keyword(s):

Magnetic Field ◽

Applied Magnetic Field ◽

Constant Magnetic Field ◽

Numerical Study ◽

Three Dimensional ◽

Navier Stokes ◽

Structural Reorganization ◽

Direct Numerical Solution ◽

Flow Circulation ◽

Buoyancy Driven Convection

The effects of a constant magnetic field on electrically conducting liquid-metal flows in a parallelepiped cavity are investigated using a spectral numerical method involving direct numerical solution of the Navier–Stokes and Ohm equations for three-dimensional flows. Three horizontal Bridgman configurations are studied: buoyancy-driven convection in a confined cavity and in a cavity where the top boundary is a stress-free surface and thirdly, thermocapillary-driven flow in a cavity where the upper boundary is subjected to effects of surface tension. The results of varying the Hartmann number (Ha) are described for a cavity with Ax = L/H = 4 and Ay = W/H = 1, where L is the length, W is the width and H is the height of the cavity. In general, an increase in the strength of the applied magnetic field leads to several fundamental changes in the properties of thermal convection. The convective circulation progressively loses its intensity and when Ha reaches a certain critical value, which is found to depend on the direction (longitudinal or vertical) of the applied magnetic field, decrease of the flow intensity takes on an asymptotic form with important changes in the structure of the flow circulation. The flow structure may be separated into three regions: the core flow, Hartmann layers which develop in the immediate vicinity of the rigid horizontal boundaries or at the endwalls, and parallel layers appearing in the vicinity of the sidewalls. The behaviour of the maxima of velocity and of the overall flow circulation is found to depend on both the boundary conditions used and the direction of the applied magnetic field. Furthermore, the interaction of the electric current density with the applied magnetic field which leads to the structural reorganization described above can also create more subtle flow modifications, such as flow inversions which are observed mainly in the central region of the cavity.

Download Full-text

A comparison between electron orbits for both an axial magnetic field and an ion-channel guiding in a FEL with an electromagnetic wave wiggler

Journal of Plasma Physics ◽

10.1017/s0022377807006873 ◽

2008 ◽

Vol 74 (2) ◽

pp. 187-196 ◽

Cited By ~ 3

Author(s):

H. MEHDIAN ◽

S. JAFARI

Keyword(s):

Magnetic Field ◽

Electromagnetic Wave ◽

Ion Channel ◽

Free Electron ◽

Free Electron Laser ◽

Large Amplitude ◽

Electromagnetic Waves ◽

Axial Magnetic Field ◽

Numerical Study ◽

Guide Magnetic Field

AbstractThe operation of a free-electron laser (FEL) with electromagnetic wave wiggler in the presence of an ion-channel guiding as well as an axial guide magnetic field is considered and compared. Theoretical studies of electron trajectories and dispersion relations in a combined ion electrostatic field as well as large-amplitude backward-propagating electromagnetic waves are analyzed. The large-amplitude wave acts like a magnetostatic wiggler in a FEL. The results of a numerical study are presented and discussed. It is shown that in the wiggler pumped ion-channel free-electron laser (WPIC-FEL), electron orbits and dispersion relation are time-dependent, and over time, electron orbits while oscillating bear a periodic motion.

Download Full-text

Numerical Simulation of Free Convection Heat Transfer of Ferrofluid in an Oval Shaped Closed Loop

Asian Journal of Engineering and Applied Technology ◽

10.51983/ajeat-2018.7.2.958 ◽

2018 ◽

Vol 7 (2) ◽

pp. 43-47

Author(s):

Jaswinder Singh Mehta ◽

Rajesh Kumar

Keyword(s):

Magnetic Field ◽

Heat Transfer ◽

Permanent Magnet ◽

Applied Magnetic Field ◽

Closed Loop ◽

Numerical Study ◽

Convection Heat Transfer ◽

Maximum Velocity ◽

Free Convection Heat ◽

Spatially Varying

Free convective heat transfer capability of kerosene based ferrofluid flowing through an oval shaped two-dimensional closed loop has been investigated numerically. COMSOL Multi Physics, a standard CFD code has been applied for solving the governing equations. A constant magnetic field was applied using permanent magnet and time dependent numerical study has been conducted for laminar fluid flow and heat transfer. The fluid was found to flow under the effect of externally applied magnetic field and spatially varying temperature. Maximum velocity of 4.43 mm/s has been found under the influence of externally applied magnetic field generated by the permanent magnet and flow was observed to be continuous. Temperature and velocity plots have also been plotted reconfirming the candidature of ferrofluid as a coolant for heat transfer applications of mini/micro devices.

Download Full-text