Dear Didier,
I noticed discrepancies between the phase advances calculated using two methods in TraceWin. One method involves integrating the beta function obtained from the envelope charts (as shown in Fig. 1), while the other method uses the phase advance per meter (kx) from the tracking file (partran.out). The differences between these two sets of phase advances are illustrated in Fig. 3. What could be the reason for these discrepancies?
Best regards,
Emily
ps. The project files are attached.
Different values of phase advance
Different values of phase advance
- Attachments
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lattice.zip- (16.09 MiB) Downloaded 48 times
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- 1.png (535.36 KiB) Viewed 831 times
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- 2.png (221.26 KiB) Viewed 831 times
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- 3.png (37.44 KiB) Viewed 831 times
Re: Different values of phase advance
Dear Emily,
Figures 1 and 2 should normally give the same plot, and that's the case with me. In any case, I understand your problem, i.e. the discrepancies between envelope phase advance and tracking.
If I do the same as you, but using TraceWin (see my image for the method), I get a smaller discrepancy than your last plot.
Now, it's normal to find a difference because the envelope calculation calculates the phase advance at each calculation step, whereas in tracking it's based on an average made between the input and output of the element. You have to cut the elements into small pieces to get something very close.
Regards,
Didier
Figures 1 and 2 should normally give the same plot, and that's the case with me. In any case, I understand your problem, i.e. the discrepancies between envelope phase advance and tracking.
If I do the same as you, but using TraceWin (see my image for the method), I get a smaller discrepancy than your last plot.
Now, it's normal to find a difference because the envelope calculation calculates the phase advance at each calculation step, whereas in tracking it's based on an average made between the input and output of the element. You have to cut the elements into small pieces to get something very close.
Regards,
Didier
- av.png (712.14 KiB) Viewed 607 times
Re: Different values of phase advance
Dear Didier,
I am not referring to the differences between results from choosing "Partran" and results from choosing "Envelope". All the data represented in Fig.3 are obtained by choosing the results from Partran. The data labeled as "σx_envelope" comes from the "envelope" plot on the beam charts panel(please see the attached file), while the data labeled as "σx_partran" is from the partran.out file.
Yes, it's normal to find a difference between results from small pieces and those obtained from averaging, but the discrepancy seems too big. As illustrated in Fig.3, by the end of the beamline, the difference has exceeded 70 degrees(with one of 384.957615 degrees and 312.2687 degrees from the other).
Best regards,
Emily
I am not referring to the differences between results from choosing "Partran" and results from choosing "Envelope". All the data represented in Fig.3 are obtained by choosing the results from Partran. The data labeled as "σx_envelope" comes from the "envelope" plot on the beam charts panel(please see the attached file), while the data labeled as "σx_partran" is from the partran.out file.
Yes, it's normal to find a difference between results from small pieces and those obtained from averaging, but the discrepancy seems too big. As illustrated in Fig.3, by the end of the beamline, the difference has exceeded 70 degrees(with one of 384.957615 degrees and 312.2687 degrees from the other).
Best regards,
Emily
- Attachments
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- partran.out
- (20.57 KiB) Downloaded 33 times
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- envelope plot.txt
- (400.71 KiB) Downloaded 33 times
Re: Different values of phase advance
Dear Emily,
Ok, I think I understand now. On my side, using my method, both give the same results, because in both cases I use phase advance values from the partan.out file. You're mixing phase advance values with beta functions, so I think you're confusing the beta function with the phase advance.
https://dacm-codes.fr/Softwares/TraceWi ... Y_function
https://dacm-codes.fr/Softwares/TraceWi ... definition
Regards,
Didier
Ok, I think I understand now. On my side, using my method, both give the same results, because in both cases I use phase advance values from the partan.out file. You're mixing phase advance values with beta functions, so I think you're confusing the beta function with the phase advance.
https://dacm-codes.fr/Softwares/TraceWi ... Y_function
https://dacm-codes.fr/Softwares/TraceWi ... definition
Regards,
Didier