Elegant users forum

In my Linac tracking simulation, momentum spread does not increase in many parts
having several consecutive CSRDRIFTs with LSC on.
This is an example for case of no momentum-spread(s6) increase.
s ElementName enx eny s1 s3 s6 s7
1.488436e+00 L200 1.658595e-06 1.548557e-06 3.703764e-04 2.686926e-04 2.045267e-03 2.015855e-12
1.688436e+00 L200 1.658595e-06 1.548557e-06 3.801305e-04 2.428612e-04 2.045267e-03 2.016971e-12
1.888436e+00 L200 1.658595e-06 1.548557e-06 3.915903e-04 2.227507e-04 2.045267e-03 2.018087e-12
2.088436e+00 L200 1.658595e-06 1.548557e-06 4.046107e-04 2.100114e-04 2.045267e-03 2.019203e-12
2.288436e+00 L200 1.658595e-06 1.548557e-06 4.190463e-04 2.060150e-04 2.045267e-03 2.020320e-12
2.300436e+00 L12 1.658595e-06 1.548557e-06 4.199544e-04 2.060700e-04 2.045267e-03 2.020387e-12
2.500436e+00 L200 1.658595e-06 1.548557e-06 4.357364e-04 2.118580e-04 2.045267e-03 2.021503e-12
2.686436e+00 L186 1.658595e-06 1.548557e-06 4.514338e-04 2.249201e-04 2.045267e-03 2.022541e-12
2.686436e+00 BPM11 1.658595e-06 1.548557e-06 4.514338e-04 2.249201e-04 2.045267e-03 2.022541e-12
2.828436e+00 L142 1.658595e-06 1.548557e-06 4.640163e-04 2.391370e-04 2.045267e-03 2.023334e-12
2.833436e+00 L5 1.658595e-06 1.548557e-06 4.644682e-04 2.396960e-04 2.045267e-03 2.023362e-12

This is an example for case of momentum-spread increase in the same accelerator.
3.120349e+01 QMIM01 4.711888e-06 1.372434e-06 9.746041e-04 1.210015e-03 2.874948e-03 2.206710e-12
3.120349e+01 LSCQMIM 4.711809e-06 1.372474e-06 9.746041e-04 1.210015e-03 2.885936e-03 2.206710e-12
3.140349e+01 L200 4.711599e-06 1.372537e-06 1.076270e-03 1.145493e-03 2.907976e-03 2.208318e-12
3.160349e+01 L200 4.711490e-06 1.372567e-06 1.178550e-03 1.081014e-03 2.918846e-03 2.209929e-12
3.180349e+01 L200 4.711376e-06 1.372596e-06 1.281295e-03 1.016586e-03 2.929631e-03 2.211545e-12
3.200349e+01 L200 4.711259e-06 1.372623e-06 1.384402e-03 9.522192e-04 2.940339e-03 2.213168e-12
3.220349e+01 L200 4.711136e-06 1.372648e-06 1.487796e-03 8.879273e-04 2.950971e-03 2.214796e-12
3.240349e+01 L200 4.711008e-06 1.372672e-06 1.591421e-03 8.237276e-04 2.961530e-03 2.216430e-12
3.260349e+01 L200 4.710875e-06 1.372693e-06 1.695235e-03 7.596437e-04 2.972016e-03 2.218070e-12
3.280349e+01 L200 4.710737e-06 1.372713e-06 1.799204e-03 6.957074e-04 2.982431e-03 2.219715e-12
3.300349e+01 L200 4.710594e-06 1.372731e-06 1.903304e-03 6.319636e-04 2.992776e-03 2.221366e-12

Drift space elements such as L200, L186 and L5 are defined as
L200: CSRDRIFT,L=0.2,DZ=0.05,USE_STUPAKOV=1,LSC_BINS=100

Is this result reasonable?
The Elegant versions I used are both 2020.2.0 and 35.1.0. The result is not changed.
Thank you in advance.

Norio

Norio,

The problem may be that there is no CSRCSBEND in the lattice, or you don't have a CHARGE element. If you want LSC without CSR, use the LSCDRIFT element.

--Michael

Thank you very much for your helpful advice.
As you said, most of the CSRDRIFTs without momentum spread change were not preceded by any CSRCSBEND.
I thought CSRDRIFT could work as LSCDRIFT when CSRCSBEND did not precede it or there was no CSRCSBEND.
I will change them to LSCDRIFTs to continue the simulation work correctly.
I want to confirm if both CSR and LSC effects are applied to the CSRDRIFTs even if the CSRCSBEND in the
upstream beam line is much far from them and other elements such as magnets are inserted between them ?

Next I have another question about the same simulation result.
In the attached figure of the momentum spread along the beam path, there are two small jumps pointed by
arrows.
I also write the beam parameter values around the two jumps below.

(first jump)
s ElementName enx eny s1 s3 s6 s7
m m m m m
----------------------------------------------------------------------------------------------------------------------
5.403940e+01 UND0 4.942666e-06 1.364015e-06 7.508230e-04 6.703885e-05 4.194293e-03 2.453066e-12
5.403940e+01 LSCUND 4.942658e-06 1.364015e-06 7.508230e-04 6.703885e-05 4.195689e-03 2.453066e-12
5.406340e+01 UND0 4.942658e-06 1.364015e-06 7.587436e-04 6.701946e-05 4.195689e-03 2.453611e-12
5.406340e+01 LSCUND 4.942651e-06 1.364015e-06 7.587436e-04 6.701946e-05 4.197081e-03 2.453611e-12
5.407540e+01 L12 4.942186e-06 1.363648e-06 7.626965e-04 6.756361e-05 4.353881e-03 2.454347e-12
5.407540e+01 MUC1 4.942186e-06 1.363648e-06 7.626965e-04 6.756361e-05 4.353881e-03 2.454347e-12
5.413040e+01 L55 4.942168e-06 1.363649e-06 7.809790e-04 7.883722e-05 4.357051e-03 2.454996e-12
5.423040e+01 L100 4.942135e-06 1.363651e-06 8.145529e-04 1.212341e-04 4.362717e-03 2.456176e-12

(second jump)
5.934340e+01 UND0 5.287413e-06 1.332789e-06 5.562782e-04 7.090761e-05 4.661286e-03 2.556012e-12
5.934340e+01 LSCUND 5.287414e-06 1.332789e-06 5.562782e-04 7.090761e-05 4.662646e-03 2.556012e-12
5.936740e+01 UND0 5.287414e-06 1.332789e-06 5.606285e-04 7.316038e-05 4.662646e-03 2.556621e-12
5.936740e+01 LSCUND 5.287415e-06 1.332790e-06 5.606285e-04 7.316038e-05 4.664003e-03 2.556621e-12
5.937940e+01 L12 5.287677e-06 1.332935e-06 5.628551e-04 7.453188e-05 4.809932e-03 2.557338e-12
5.937940e+01 MUC2 5.287677e-06 1.332935e-06 5.628551e-04 7.453188e-05 4.809932e-03 2.557338e-12
5.957940e+01 L200 5.287685e-06 1.332936e-06 6.022680e-04 1.458146e-04 4.821001e-03 2.560116e-12
5.967940e+01 QMIS11 5.197001e-06 1.336407e-06 5.565419e-04 2.130440e-04 4.821001e-03 2.561525e-12
5.967940e+01 LSCQMIS10 5.196916e-06 1.336408e-06 5.565419e-04 2.130440e-04 4.826405e-03 2.561525e-12
5.972940e+01 L50 5.196788e-06 1.336409e-06 5.014383e-04 2.579642e-04 4.834511e-03 2.562271e-12

Both jumps occur at L12 elements (CSRDRIFT elements with LSC on) just after two undulators made of WIGGLER
elements(UND0) and LSCDRIFT elements having the same effective length (LSCUND), which are defined below.

UND0: WIGGLER,L=0.024,K=1.421,POLES=2
LSCUND: LSCDRIFT,LEFFECTIVE=0.024,BINS=100

There are two more L12 elements just before the two undulators, but such jumps of the momentum spread are not found.
I cannot understand why these jumps of the momentum spread appear in the short drifts (L12) only at the exits of the undulators.
Please let me know if you understand or find the reason.
Thank you in advance.

Norio