Reflection symmetries of rays in a magnetic field, 3D only.

Reflections of rays in a magnetic field are different from reflections when there is no magnetic field.

This note concerns reflection and inversion symmetries that can be applied to the rays when the is a magnetic field. This option is available only when a magnetic field is present.

The rays can be reflected in any or all of the symmetry planes that have been selected. The planes are the yz (that is, x = 0), zx (that is, y = 0), xy (that is, z = 0) and x = y planes.

The reflections that the user selects are combined to make a single operation -that is, they are not taken separately in sequence. The combined operation is used to create new rays.

In a magnetic field the rays usually have inversion symmetry. For example if the magnetic field is in the z direction and a certain ray passes through a series of points with coordinates (x,y,z), then a second ray that passes through the points (-x,-y,z) is also a valid ray. This second ray is obtained from the first by reflection in the x= 0 and y = 0 planes simultaneously. This has the effect of simultaneously transforming x to -x and y to -y. Note that the operations are applied simultaneously to give a single operation -unlike the reflections described in the note on ray reflections, which remain separate operations.

The reflected rays appear on the screen in all the 2D and 3D pictures, but are not entered in the output data file. The interpolated points in the original rays (if these exist) are not included.

The beam section also contains the crossing points of the reflected rays (unless the beam section plane is inclined in such a way that these reflections are not appropriate for the beam section).

Warning: Rays can only be reflected in planes that were initially defined to be planes of reflection symmetry. If other planes are specified here the program will stop.

For users who are editing or constructing an 'input data file' without the use of the data-builder -that is, pre-processor:

But Manual editing is certainly not recommended -it is a relic from the time when the databuilder was not available All users are strongly encouraged to use the databuilder, which always gives the correct formats and which has many options for which the formats are not described or easily deduced.

To apply reflections to the calculated rays, in selected planes, enter a line that contains 4 numbers, all of which are either 0 or 1.

For no reflections, enter '0 0 0 0'.

The reflections denoted by 1 are combined to make a single operation (that is, they are not taken separately in sequence) and are applied to the yz (that is, x = 0), zx (that is, y = 0), xy (that is, z = 0) and x = y planes to create new rays.