Outputting space charge density.
This option is accessed from the top bar, after the run has finished.
The space-charge density calculated here is that of the rays only -it does not include the space-charges on the virtual cathode segments.
When the tube method is used:
The user is asked to choose the ‘averaging radius’. The program will not allow this to be less than the ‘tube radius’ selected by the user. The space-charge density is averaged over a sphere that has this radius.
The density is in Coulomb per cubic metre.
Some warnings:
When the cell method is used:
The space-charge density is constant inside each cell, which leads to discontinuities in the map of space-charge density contours.
For CPO2DS only:
The option should not be used when there are near-axis non-meridional rays.
For CPO3DS only:
When x=y is a plane of reflection symmetry the space-charge cells do not have this symmetry in the vicinity of the plane, and so the space-charge density will be inaccurate near this plane.
See general note on contours for more details.
An extra option, not available in databuilder, for outputting charge density information.
Triggered by putting ‘q’ in 12th space of line that holds cell spacing or tube radius.
The 13th space has ‘x’ or ‘r’ for xyz or radial information.
The next line (an extra line) has minimum x,y,z and maximum x,y,z for ‘x’, or minimum r,z and maximum r,z for ‘r’.