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space-charge tune shifts effect
Posted: 08 Mar 2016, 21:39
by tiansk
Hello everybody
I want to test the space-charge tune shifts effect with the elegant.Without the SCMULT element,we could set one particle with offset,with the help of sddsfft,we could get the tune of the storage ring.Is it possible to get the tune with &insert_sceffects to include the space-charge by the same method? If not,how could I test the space-charge tune shifts effect?
Many thanks in advance
tiansk
Re: space-charge tune shifts effect
Posted: 10 Mar 2016, 09:08
by michael_borland
Tiansk,
You can use a WATCH element with mode="coordinate", then do NAFF analysis for each particle:
Code: Select all
sddsregroup run.wcoord -pipe=out -newParameters=particleID -newColumns=Pass \
| sddsnaff -pipe -column=Pass -pair=x,xp -pair=y,yp -terminateSearch=frequencies=1 \
| sddscombine -pipe -merge |
| sddsprocess -pipe -process=*Frequency,ave,%sAve -process=*Frequency,stand,%sStDev \
| sddsprintout -pipe -parameter=*Frequency*
You may need to track many particles to reduce noise, so using Pelegant is recommended. Using the START_PID and END_PID parameters on the WATCH element can reduce the number of particles for which data is logged, which will make things faster.
If you are comparing to handbook formulae, you need to suppress longitudinal motion, which can be done by removing rf cavities and synchrotron radiation, and by using a beam with no energy spread (to keep fixed bunch length).
--Michael
Re: space-charge tune shifts effect
Posted: 17 Oct 2017, 20:56
by ChongChong
If we were removing rf cavities and synchrotron radiation, using a beam with no energy spread (to keep fixed bunch length),
how could I accurately count the emittance caused by space-charge effect?