CEA Codes forum

Hello Didier,
I want to study the misalignment effect on a beamline enclosing electrostatic quadrupoles and RF drift tubes. These electrodes have certain misalignments. This misalignment is kind of shifting relative to the central axis as well as twisting. To simulate the misalignment effect I used the following instructions:
- Shift dx dy
This instruction showed clearly the shifting effect on the beam.
- ERROR_CAV_NCPL_STAT 1 0 dx dy dxp dyp 0 0 0
I used this instruction for electrodes like drift tubes to study the shifting and twisting effect. No effect occurred even with large shift and twisting parameters.
I got the same effect on the shift of the quadrupoles if I change the instruction "shift dx dy" by "ERROR_quad_ncpl_stat 1 0 dx dy 0 0 0 0 0"
I want to verify the use of these instructions and their effects. below you have an example of the use of these instructions.
Example:
shift dx dy
;ERROR_quad_ncpl_stat 1 0 dx dy 0 0 0 0 0
QUAD_ELE 90 V1 10 0 0 0 0 0 0
freq 2
ERROR_CAV_NCPL_STAT 1 0 dx dy dxpr dypr 0 0 0
FIELD_MAP 700 100 30 15 0 Va 0 0 FM 1

Dear Sir,

Commands of type ERROR_XXX are only used to specify the range of errors. You also need to specify in the interface, on the ‘Errors’ -> ‘Error Setup’ page, which errors you want to apply and for how many runs you want to do.
Then, you need to know whether you want to do just one run or statistics on N runs, it's not the same procedure.
Have you read the "Errors study management" chapter, which might help.
Finally, if you don't succeed, send me your project files so that I can understand exactly what you're doing.

Regards,

Didier