Field emission crashes
The reasons for field emission crashes are invariably either that
(1) The initial ray conditions are incorrect, or
(2) the other, later ray conditions are incorrect, or
(3) (less likely) that the requested inaccuracies for calculating the charges or the ray tracing are too large, or
(4) (for 3D only) the program is searching for the magnetic field at a point outside the range defined by the User.
Very rarely, the solution is to delete the processed data file and re-start, or to change the name of the processed data file.