Sign of summation in second order RDTs wrt sextupoles
Posted: 07 Oct 2024, 05:23
Dear all,
I have a doubt about the summation used in the calculation of the second order rdts with respect to sextupoles.
I see that in the elegant file 'twiss.cc' line 4997 the sign of the sum is written as
which is negative for j>i, being j downstream wrt to i.
This termSign is the opposite to the Equation (46) by Chun-Xi Wang "Explicit formulas for 2nd-order driving terms due to sextupoles and chromatic effects of quadrupoles". ANL/APS/LS-330. March 10, 2012.
Is this difference a sign convention in Elegant ? or is there any other reason ?
Best regards,
o
I have a doubt about the summation used in the calculation of the second order rdts with respect to sextupoles.
I see that in the elegant file 'twiss.cc' line 4997 the sign of the sum is written as
Code: Select all
termSign = SIGN(ed[iE].s - ed[jE].s);This termSign is the opposite to the Equation (46) by Chun-Xi Wang "Explicit formulas for 2nd-order driving terms due to sextupoles and chromatic effects of quadrupoles". ANL/APS/LS-330. March 10, 2012.
Is this difference a sign convention in Elegant ? or is there any other reason ?
Best regards,
o