CEA Codes forum

Dear Didier,

In order to simulate dtl tank tilt error, is it possible to use input beam error with dx, dx' , dy, dy' errors?

Regards,

Shweta

Drar Shweta Roy,

Either you put a tilt on the tank with ERROR_QUAD_XXX command, or you use the BEAM_ROT command in front of your tank and the same reversed at the exit of your tank. This will be more equivalent than just applying a tilt to the input beam.

Regards,

Didier

ERROR_QUAD command will not account for rf gap tilt, will it?

Also, why beam tilt is not appropriate?

Best Regards,

Shweta

Dear Shweta,

No, I confirm that the opposite error must be applied to the output of the element for it to be equivalent to the direct approach. In fact, that is how it is done in reality. No error is actually applied to the elements, but rather to the input and output of the beam. Imagine a tilt on a quadrupole with a magnetic field set to 0. If you only apply the tilt to the beam at the input, the beam will exit at an angle, whereas it should remain on the axis if the field is zero. The error should be viewed simply as a change in the beam's reference point when it passes through the element in question.

Regards,

Didier

Dear Didier,

Thanks for the explanation. As regards the coupled quad error the tilted RF gaps isn't accounted. So, the error results may give an underestimate of the solution?

Best Regards,

Shweta.

Dear Shweta,

I agree, but it's really second class effet, for small displacement corresponding to the usual errors.

Regards,

Didier

Dear Didier,

I understand that when we give quad error, TraceWin actually applies the error in beam reference point and then reverses the error at the output of the quad. In case of coupled quad errors, is it done in the same way, i.e., reversing initial error after individual quad or the error is actually reversed after the last quad no. to which error is applied? if it the latter case, rf gap tilts can be accounted too. Please clarify.

Best Regards,

Shweta.

Dear Shweta,

Yes, in case of coupled quad errors, is it done in the same way.

Regards,

Didier

Dear Didier,

Thanks for the clarification! This means the gap tilts in DTL is also accounted when we give coupled quad error.

Best Regards,

Shweta.