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Magnetic fields are everywhere in nature and they play an important role in every astronomical environment which involves the formation of plasma and currents. It is natural therefore to suppose that magnetic fields could be present in the…

Cosmology and Nongalactic Astrophysics · Physics 2011-12-22 Dai G. Yamazaki , Kiyotomo Ichiki , Toshitaka Kajino , Grant J. Mathew

Permanent magnet has a small and compact structure, is especially suitable for a narrow space. With the aid of soft iron, the magnetic field can be increased much more and the field uniformity can be well controlled. Most Permanent magnets…

Accelerator Physics · Physics 2023-01-03 Quanling Peng , Jianxin Zhou , Saike Tian , Yingzhe Wang

Among the algorithms that are likely to play a major role in future exascale computing, the fast multipole method (FMM) appears as a rising star. Our previous recent work showed scaling of an FMM on GPU clusters, with problem sizes in the…

Numerical Analysis · Computer Science 2012-10-30 Rio Yokota , Lorena Barba

A permanent magnet array (PMA) is a preferred source of magnetic field for body-part-dedicated low-field (<0.5 T) portable magnetic resonance imaging (MRI) because it has a small footprint, no power consumption, and no need for a cooling…

Medical Physics · Physics 2022-11-23 Ting-Ou Liang , Yan Hao Koh , Tie Qiu , Erping Li , Wenwei Yu , Shao Ying Huang

This lecture note describes how to set up and what is behind a magnetodynamic field simulation for an accelerator magnet. The relevant formulation of Maxwell's equations is derived. The formulation is discretized in space by the…

Accelerator Physics · Physics 2020-06-19 H. De Gersem , I. Cortes Garcia , L. A. M. D'Angelo , S. Schöps

The fast multipole method (FMM) has had great success in reducing the computational complexity of solving the boundary integral form of the Helmholtz equation. We present a formulation of the Helmholtz FMM that uses Fourier basis functions…

Numerical Analysis · Mathematics 2014-03-20 Cris Cecka , Eric Darve

We present a framework and an open-source python toolkit to analyse the 2-point statistics of 3D fluctuations in the context of HI intensity maps using the multipole expansion formalism. We include simulations of the cosmological HI signal…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-19 Steven Cunnington , Alkistis Pourtsidou , Paula S. Soares , Chris Blake , David Bacon

In this work we present a variant of the fast multipole method (FMM) for efficiently evaluating standard layer potentials on geometries with complex coordinates in two and three dimensions. The complex scaled boundary integral method for…

Numerical Analysis · Mathematics 2025-10-20 Tristan Goodwill , Leslie Greengard , Jeremy Hoskins , Manas Rachh , Yuguan Wang

Fast multipole methods (FMM) were originally developed for accelerating $N$-body problems for particle-based methods. FMM is more than an $N$-body solver, however. Recent efforts to view the FMM as an elliptic Partial Differential Equation…

Numerical Analysis · Mathematics 2016-08-09 Huda Ibeid , Rio Yokota , David Keyes

I describe a modification to the original Fast Multipole Method (FMM) of Greengard & Rokhlin that approximates the gravitation field of an FMM cell as a small uniform grid (a "gridlet") of effective masses. The effective masses on a gridlet…

Computational Physics · Physics 2019-07-31 Nickolay Y. Gnedin

Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments…

Cosmology and Nongalactic Astrophysics · Physics 2012-08-16 Dai G. Yamazaki , Toshitaka Kajino , Grant J. Mathew , Kiyotomo Ichiki

To power gamma-ray bursts and other high-energy events, large-scale magnetic fields are required to extract rotational energy from compact objects such as black holes and neutron stars. The magnetorotational instability (MRI) is a key…

High Energy Astrophysical Phenomena · Physics 2025-09-17 Alexis Reboul-Salze , Loren E. Held , Kenta Kiuchi

Point multipole expansions are widely used to gain physical insight into complex distributions of charges and to reduce the cost of computing interactions between such distributions. However, practical applications that typically retain…

Classical Physics · Physics 2015-06-03 Charles Baker , Ramu Anandakrishnan , Alexey Onufriev

For magnetic field calculations, cylindrical permanent magnets are often approximated as ideal, azimuthally symmetric solenoids. Despite the frequent usage of this approximation, research papers demonstrating the validity and limitations of…

Instrumentation and Detectors · Physics 2022-07-21 David Shulman

The use of an external transverse magnetic field to trigger and to control electron self-injection in laser- and particle-beam driven wakefield accelerators is examined analytically and through full-scale particle-in-cell simulations. A…

Plasma Physics · Physics 2011-08-24 J. Vieira , S. F. Martins , V. B. Pathak , R. A. Fonseca , W. B. Mori , L. O. Silva

A Multi-dipole line cusp configured Plasma Device (MPD) having six electromagnets with embedded Vacoflux-50 as a core material has been operated with a capability to experimentally control the field-free region, the radial profile of…

Plasma Physics · Physics 2022-05-31 A. D. Patel , A. Amardas , N. Ramasubramanian

This paper presents an overview of the theories and computer implementation aspects of phase field models (PFM) of fracture. The advantage of PFM over discontinuous approaches to fracture is that PFM can elegantly simulate complicated…

Geophysics · Physics 2023-09-11 X. Zhuang , S. Zhou , G. D. Huynh , P. Areias , T. Rabczuk

This paper proposes a nonlinear magnetics model for Permanent Magnet Synchronous Machines (PMSMs) that accurately captures the effects of magnetic saturation in the machine iron and variations in rotor temperature on the permanent magnet…

Systems and Control · Electrical Eng. & Systems 2025-02-05 Kishan Srinivasan , Heath Hofmann , Jing Sun

Analytical models of axially symmetric thin disks of finite extension in presence of magnetic field are presented based on the well-known Morgan-Morgan solutions. The source of the magnetic field is cons\-tructed separating the equation…

Astrophysics of Galaxies · Physics 2016-04-11 Edinson Cardona-Rueda , Gonzalo García-Reyes

In boundary element methods (BEM) in $\mathbb{R}^3$, matrix elements and right hand sides are typically computed via analytical or numerical quadrature of the layer potential multiplied by some function over line, triangle and tetrahedral…

Numerical Analysis · Mathematics 2023-04-06 Nail A. Gumerov , Shoken Kaneko , Ramani Duraiswami