MacResearch

In 'Showcase' reviews, the reviewer is the developer. No claim of objectivity is made, but it’s a chance for the developer to show off his/her app. Here, Meritt Reynolds of Ripplon Software Inc. discusses BiotSavart, an application for designing experiments involving magnetism.

The purpose of BiotSavart is to facilitate the design of experiments employing magnetic fields. It does this by providing an intuitive and interactive environment in which it is easy to explore various design possibilities. You specify a three-dimensional system of conductors with specified geometry, and BiotSavart calculates quantities such as the magnetic field, force, torque, and linked flux. Visualization of the configuration with superimposed field lines, contour plots, or volumetric information promotes understanding of the system under analysis.

BiotSavart deals with electromagnetism: the magnetic field generated by current-carrying conductors. Conductor objects may be arbitrarily oriented and placed in three dimensions. An external bias magnetic field can be superimposed on the configuration. The resulting magnetic field may be sampled and displayed in various ways, using probe objects.

The conductor types are Loop, Solenoid, Revolved, Wire, and Racetrack. The probe objects are Tracer, Linear, Planar, and Volumetric.

How it looks

The user interface of BiotSavart is centered on a configuration window, that shows you a view of the system you are working with. This view has animated rotation and zoom which helps to maintain perspective. When you are modifying conductors or probes, there will also be edit windows for these objects.

Graphs of magnetic fields, gradients, and so on are displayed in probe windows. The configuration window and probe windows update whenever you make a change to the conductors or their current supplies. For a Linear probe the probe window displays a plot as shown below. The plot is interactive. Click on a curve to display the value. Scroll along the curves with the arrow keys.

A Planar probe object generates a contour plot (of any quantity) on a specified planar surface. The contour plot appears superimposed on the graphical display of the conductors. It may also be plotted in a window of its own.

A Volumetric probe object calculates the magnetic field in a rectangular box. From this data it can display arrows indicating the direction and magnitude of either the vector potential or the magnetic flux density. It can also display a level-set surface of any quantity. A slider control lets the value of the level-set be adjusted continuously in real time.

The figure below shows the view on the configuration windown for a coil pair with a contour plot as well as a volumetric probe displaying a level set.

Field line tracing

To trace magnetic field lines, you create a Tracer probe object. The example below shows the chaotic nature of a field line generated by a kinky loop (in the program you can swivel the view to look at the loop and field line from any angle):

Inductance and force calculations

If you want to know how your conductors interact with one another, BiotSavart can calculate self-inductance and linked flux for solenoids, loops, and wires. BiotSavart calculates linked flux (and hence mutual inductance) even in geometries that are not axially symmetric.

Likewise, BiotSavart can calculate the force and torque acting on any of the conductors in a configuration, regardless of its symmetry (or lack thereof).

Saving data

If you want to analyze calculated data using other applications, it may be saved to a file. Saved data may include magnetic vector potential, magnetic flux density, and gradients of the magnetic flux density. The trajectory of magnetic field lines may also be saved.

More information

For more information about BiotSavart, visit its web page. To experience how it can save you time in your design work, just give it a try!

About the author

Meritt Reynolds is the author of BiotSavart and the other software products of Ripplon Software Inc. He has a Ph.D. in experimental physics and has extensive experience working in both academia and industry.