Edit windows
About this page
This page is an overview of the conductor edit window, using a solenoid object as an example.
Obtaining an edit window
When you create a new object (conductor or probe), you will be presented with its edit window.
To edit an existing object, double-click on its picture on the configuration window, or select its name from the Modify menu. This will cause its edit window to be presented.
Using an edit window
The name of the edit window is the name of the object being modified. Below the Apply, Done, and Cancel buttons is the tab selection tabs, which allow you to select information on the object by category. At the bottom left of the window is the type of the object (e.g., Loop, Solenoid, etc.).
Once you have modified all of the parameters that you want to, the changes must be transmitted to the configuration window by pressing the Apply button (or the Done button to simultaneously close the edit window). If AutoRecompute is enabled, the magnetic field will be recalculated immediately. Be aware that AutoRecompute is disabled whenever you create a new object.
As usual, the Cancel button dismisses the edit window without transmitting the changes.
For a conductor the primary specification parameters are on the Spec tab.
The Spec tab describes things like the physical dimensions of the object or, in the case of a wire, its path through space. Note that the dimensions of the object may have units, just enter the units symbol after the number.
The Spec tab is shown here for a solenoid:
The position and orientation (Euler angles) of the conductor are specified on the Position tab of the conductor's edit dialog:
Euler angles are specified in degrees.
The orientation of the conductor is specified by three Euler angles. For an axially symmetric conductor such as a loop or solenoid, eulerPsi has no effect on the magnetic field but can be used to rotate conductors with visual cutaways. Angles are specified in degrees, and default values are zero. The conductor is rotated about the origin of its own coordinate system, before being moved to its position.
Supply tab
The name of the current supply and a scale factor is set on the Sup tab:
All conductors have an associated current supply, whose name can be any string not containing blanks. Several conductors can use the same current supply. The use of labelled supplies greatly accelerates recalculation of the magnetic fields when only the current is changed. To use current supply named kepco for the conductor enter this name into the Supply name box on the supply tab of the edit window, as shown above. An overall scale factor for the current is specified by the Scale factor box. A typical use of the scale factor would be to set it to -1 to reverse the power supply. The current supplies themselves are set by bringing up an edit window for the Current object (using the Modify menu).
Winding tab
The number of windings is specified on this tab. For bulky conductor types (Solenoid and Racetrack) you have a choice of specifying the wire diameter, the winding, or both. You use the Specify: selector to indicate which quantity you are specifying. If only the wire diameter is specified, the winding will be calculated from the wire diameter. If only the winding is specified, the wire diameter will be calculated from the winding. If you are specifying both, you must enter numbers in both the wire diameter and winding fields.
The wire diameter is specified with units. If no units are given, the default units (meters) will be used.
The wire packing option is used to relate wireDiameter and winding when only one is specified. It is selected from the following options:
Square. To calculate the winding from the wireDiameter the cross sectional area is divided by the square of wireDiameter, rounding to the nearest integer. The reverse calculation is done without rounding, since wireDiameter need not be integral.
Hexagonal. The way wires pack naturally, a bit tighter than square packing.
Note that the choice of packing does not change the packing of conductor elements used in field calculation, only the relation between wireDiameter and winding. The conductor elements using in field calculation are always square packed.
Be sure to specify the number of turns using the winding box rather the currentScale box because for inductance calculations these are very different quantities.
Looks tab
The Looks tab describes aspects of the conductor which do not influence its magnetic field, only the way it looks on-screen.
For an axisymmetric object like a loop there will be additional parameters:
- # of phi steps
- How many segments to draw the full circle.
- starting value
- Starting value of phi for cutaway view.
- ending value
- Ending value of phi for cutaway view.
Using the starting and ending values gives a visual cutaway only, and does not influence the magnetic field. Pressing the Full circle button restores the full axisymmetric view. Note that rotation of the cutaway as a whole is possible using the eulerPsi parameter on the Posn tab, because this does not alter the magnetic field of an axisymmetric object.
Calc tab
The Calc tab specifies parameters that influence the calculation of the magnetic field:
Objects that are decomposed into loops or filaments for purposes of calculation use the resolution parameter to determine how finely the object is subdivided into loops for the calculation (see here for a discussion of this important parameter). The resolution is independent of the winding parameter that determines the number of physical windings for determination of current density and inductance.
If the paraxialEnabled checkbox is ticked, the solenoid field will be calculated using fast paraxial approximations for points closer than paraxialR to the axis, instead of summing over loops. You should experiment with this to determine if the approximation is accurate enough for your purposes.
Force and torque tab (F&N)
Force and torque can be calcualted for conductors whose edit window contains a F&N tab. The force is given in units of newtons (N) and the torque is in units of newton-meters (N m).
After making changes to the conductors or currents, you must press the Calculate button to update the values.
Torque depends on the center about which it is calculated. BiotSavart calculates the torque about the center of mass of the magnitude of the current density. For a conductor like a solenoid or racetrack, this is the geometrical center of the conductor.
Notes tab
On the Notes tab you can write notes:
Different objects have different parameters, so the edit windows will not be the same as shown here for the solenoid object. See the object descriptions for conductors and probes for details.