| This tutorial is recommended
for all newcomers to Magsimus. The design you build is of no special
significance, but you gain an overall feel of how Magsimus works. The
narrative will often be wordy to ensure that the described concepts are
well understood. The user who patiently follows the material in its
entirety will derive the maximum benefit from the tutorial.
In this tutorial you learn
the following:
- How to create a design consisting of different types of components
- How to specify the data outputs to be generated from a calculation (or simulation)
- How to define mechanical motions in a design
- How to run and record a simulation
Fig. 1 shows
our first example in its completed form. The design (referred to as the system
) consists of several objects that are indicated by the numbers in the
figure. (The numbering of the components in the figure are for
illustrative purposes; they are not generated by the software). Objects
4 and 6 will move around in space during the simulation. The objects are
(following the numbering in the figure):
- Electrical
current source
- Non-magnetic
element
- Non-magnetic element.
Elements 2 and 3 are connected electrically in parallel and supplied
by current source 1.
- A field
probe
- An array of normal
magnetic elements (cells)
- A permanent
magnet
Fig. 1. Completed design.
About Design components
The creation of a new
design involves assembling a system composed of several functionally
distinct groups that are made up of basic
design components. These components are elements, arrays of
elements, probes, shields and field arrays.
An element and a shield have shapes in the form of rectangular prisms.
Shields and field arrays will not be part of the design we describe in
this section. A complete discussion of the concept of a system, groups
and basic components is given in Chapter 4 of the user manual.
An element may be magnetic or nonmagnetic, a conductor or an
insulator. An array is a collection of elements defined on a
rectangular grid. The elements of an array are referred to as cells. A
field array is a rectangular array of points, that is used for
visualizing interaction field regions in space. It does not represent
a physical material object but a construct of points. The interaction
fields that can be visualized are the magnetostatic fields produced by
the polarization of magnetized objects as well as magnetic fields
produced by currents flowing in the system. Each field point is
centered within a cell region defined similarly as for a material
array.
A magnetic element is uniformly magnetized (or single-domain).
Its magnetization is represented by a single vector drawn as an arrow.
Each magnetic element may be a normal magnet, a pseudo-soft
magnet or a permanent magnet. The magnetization vector of a
normal magnet is fixed in magnitude but is free to rotate in three
dimensions. For a pseudo-soft magnet, both the magnitude and direction
of the magnetization vector can change. The magnitude and direction of
the magnetization vector of a permanent magnet remain fixed relative
to the element.
Coordinate systems
Various Cartesian
coordinate frames are defined to facilitate the description of the
system geometry. These are the system coordinates (
XYZ ), the local group coordinate ( UVW
) and the local coordinates of the components of a group (
uvw ). The location and orientation in space of group coordinate
frames are specified relative to the system coordinate frame, and the
origin and orientation of the coordinate frames of basic components
are specified relative to the coordinate frames of their parent
groups. Coordinate systems are discussed in Chapter 4 of the user
manual.
Calculation methods
The simulation that will be
performed on the system will be a static
one. The software will invoke a static solver
to carry out the calculations. The
static method is the default calculation method. The other calculation
methods that are available in the software are dynamic
and quasi-static
methods. The system state (including
magnetization and applied magnetic fields) are independent of time for
static calculations. Therefore, for this method, the duration and the
rate of change of physical quantities are expressed in the input
dialog boxes of the software in terms of solution
steps (for example, linear velocity
is expressed in dimensions of Distance/step). On the other hand, the
states of a modeled system using the dynamic and quasi-static methods
are time-dependent. For these methods, duration and rates of change
are expressed in terms of time. Magnetization states are not
time-dependent for quasi-static methods.
A separate solver (the dynamic
solver ) is invoked for dynamic calculations. Quasi-static
calculations share the same solver as static calculations. During
quasi-static calculations, changes in time occur as magnetic fields
are swept between equilibrium magnetic states. The calculation method
can be specified at the System Specification
dialog box, which is reachable from the System
Design Manager (described later on
in this tutorial). Solution methods are discussed in detail in Chapter
5 of the user manual.
Units
Magsimus offers a rich
choice of calculation units to fit different modeling requirements.
These units express electromagnetic, time, length and rate quantities
used in a design. Units are specified in the System
Specification dialog box. For our example, magnetic quantities (fields
and magnetization) will be expressed in CGS
units. In CGS units, field is expressed in Oe
(Oesterd) and magnetization is expressed
in emu/cc
(electromagnetic unit per cubic centimeter). An alternate system of
magnetic units available in the software is the SI units. Field and
magnetization are both expressed in A/m
(Ampere per meter) in SI units. (The coarser unit kA/m
= 1000 A/m, is used in the dialog boxes).
Length will be expressed in nm
(nanometers) throughout this tutorial.
| 