space-charge tune shifts effect

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tiansk
Posts: 39
Joined: 16 Mar 2012, 22:01

space-charge tune shifts effect

Post by tiansk » 08 Mar 2016, 21:39

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

michael_borland
Posts: 1796
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: space-charge tune shifts effect

Post by michael_borland » 10 Mar 2016, 09:08

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

ChongChong
Posts: 7
Joined: 16 Oct 2017, 07:15

Re: space-charge tune shifts effect

Post by ChongChong » 17 Oct 2017, 20:56

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?

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