Fields block

This block contains information about the EM fields specified at the start of the simulation. See EPOCH input deck for more information on the input deck.

This block allows you to specify the electric and magnetic fields at any point in the domain. An example block is shown below:

begin:fields
   ex = sin(pi * x / length_x)
   ey = cos(pi * x / length_x)
   ez = 0
   bx = 1.0
   by = -1.0
   bz = 0
end:fields

Once again, this is a very simple block needing only limited explanation. All field variables are accessible by name and can be read back using the appropriate commands from the maths parser (see here). The possible parameters are as follows:

• ex,ey,ez - The electric field vectors pointing in all three directions. The default value is zero.
• bx,by,bz - The magnetic field vectors pointing in all three directions. The default value is zero.
• offset - File offset. The field values may also be specified using a binary file in a similar way to that used for species variables. See the species block for more details. Any valid maths parser expression can be used to set up the fields, and no check is made to ensure that the $\nabla.B = 0$ is satisfied.