Probe - Linear

The linear probe calculates the magnetic field along a specified straight line or curved trajectory, and plots the result. To make a linear probe choose menu command

Config > Make probe > Linear

This will create the probe and bring up its the edit window. You will be asked for a name for the probe; enter it and close the name dialog. On the edit window the Spec tab is where you define the path and point spacing. An example path description is 

resolution 1 mm
start 0 0 0
goto 1.3 0 0 cm
resolution 0.5 mm
goto 1.3 0 2 cm

Measurement points are placed uniformly on each segment, with points on the starting and ending position and in between such that the points are no further apart than the resolution. The resolution can be changed along the trajectory as shown in the example above.

More details about the trajectory specification, for example how to make curved and spiral trajectories, is given in the file format section.

n.b., If you specify a length or position vector without units, the default units (meters) will be used.

Plot tab

The plot itself is customized by specifying what variables to plot on the Plot tab of the edit window.. By default, the field magnitude B is plotted versus z along the trajectory. The x, y, or z components of the field or vector potential can be plotted as well, with the abscissa given by either x, y, z, or the arclength s.

Note that the quantities available for plotting are in the laboratory frame, and not the object frame.

Macro tab

A macro language function can be specified on the Macro tab of the edit dialog. To plot the result of the evaluation of the macro, select the macro result (f) on the Plot tab.

Normally the plot autoscales to show all the data. This can be changed by specifying a minimum and maximum ordinate on the Scale tab of the edit window.

The probe result window

The plot will be displayed in a separate probe result window, which will have the name of the field probe enclosed in square brackets. This window will update whenever the field is recalculated.

image

In the probe product window, the cursor mode is controlled by the buttons on the upper left. The Probe mode lets you click on a curve an get a display of the calculated value at the bottom of the window. The selected point will be indicated by a small square that you can move along the curves using the left and right arrow keys on the keyboard, or between curves by using the up and down arrow keys. The Zoom mode lets you zoom in on particular areas of the graph. To zoom to fit, which is the same as turning autoscaling on, just click on the zoom icon when already in zoom mode, or use the graphics menu. When zoomed in, the Pan mode lets you move around.

Clicking the options button will jump you back to the edit dialog so you can change plotting parameters.