Wrong emittance ratio after tracking full coupling beam.
Posted: 31 Jul 2020, 02:57
Dear, everyone
I put 12 skew quadrupoles at lte file and adjusted tunes such that beam lies in different resonance.
I verified the full coupling happened from twi file as below.
couplingIntegral 6.959754783793667e-03
couplingDelta 9.320972046111820e-05
emittanceRatio 9.998206684736263e-01
I tracked beam with 240 particles and checked horizontal and vertical emittance variation according to the pass number.
however, H and V emittances doesn't become the same. The result looks like that beam become the flat beam after many turns.
I made beam with horizontal emittance 58 pm and vertical emittance 5.8 pm at the beginning.
refer the attachment PPT file.
I tried eliminate skew quadrupoles at lte file. Instread, I put normal quadrupoles' tilt errors at ele file.
I tracked beam with the same condition as the above case using skew quadrupoles.
And I checked horizontal and vertical emittance variation according to the pass number also.
The result looks like that beam become close to the round beam after many turns.
Of course, I cannot know coupling coefficient value in this situation.
Anyway, It seems which skew quadrupoles doesn't affect coupling but quadrupoles' tilt errors do.
Please, attachment file.
Sincerely,
Gyeongsu Jang
I put 12 skew quadrupoles at lte file and adjusted tunes such that beam lies in different resonance.
I verified the full coupling happened from twi file as below.
couplingIntegral 6.959754783793667e-03
couplingDelta 9.320972046111820e-05
emittanceRatio 9.998206684736263e-01
I tracked beam with 240 particles and checked horizontal and vertical emittance variation according to the pass number.
however, H and V emittances doesn't become the same. The result looks like that beam become the flat beam after many turns.
I made beam with horizontal emittance 58 pm and vertical emittance 5.8 pm at the beginning.
refer the attachment PPT file.
I tried eliminate skew quadrupoles at lte file. Instread, I put normal quadrupoles' tilt errors at ele file.
I tracked beam with the same condition as the above case using skew quadrupoles.
And I checked horizontal and vertical emittance variation according to the pass number also.
The result looks like that beam become close to the round beam after many turns.
Of course, I cannot know coupling coefficient value in this situation.
Anyway, It seems which skew quadrupoles doesn't affect coupling but quadrupoles' tilt errors do.
Please, attachment file.
Sincerely,
Gyeongsu Jang