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Problems on using FTRFMODE
Posted: 08 Jun 2023, 18:58
by WEI-HOU
Hello,
I encountered the following problem when using FTRFMODE for multi-bunch simulations.
"error: No available particle for RF cavity fiducilization"
I tried setting the factor for FTRFMODE to be very small and it still occurred.
My bunch length is about 2ps, and I set BIN_SIZE=0.3ps and N_BINS=200 to cover the entire beam.
Were my parameters wrong?
Thank you.
Re: Problems on using FTRFMODE
Posted: 14 Jun 2023, 11:32
by michael_borland
The problem is that you have CHANGE_T=1 on your RFCA elements. This can only be used if all rf elements (including RFMODE, TRFMODE, etc.) are harmonically-related. Since that isn't the case, it introduces a problem with propagation of the rf phasors for *RFMODE elements.
--Michael
Re: Problems on using FTRFMODE
Posted: 15 Jun 2023, 18:37
by WEI-HOU
Hello Michael,
Thank you for your clarification.
I also notice that 'pCetnral0' in Twiss output does not change, and therefore Twiss outputs are wrong.
Is there a way to fix this problem?
Regards
Wei-Hou
Re: Problems on using FTRFMODE
Posted: 15 Jun 2023, 18:45
by michael_borland
Wei-Hou,
Yes, you need to remove the following statement:
Code: Select all
&alter_elements name=*, type=RFCA, item=CHANGE_P0, value = 0 &end
You have CHANGE_P0=1 in the lattice file, which is what you want to keep.
--Michael
Re: Problems on using FTRFMODE
Posted: 16 Jun 2023, 12:04
by WEI-HOU
Hello Michael,
According to this thread,
viewtopic.php?f=12&t=1117
Isn't CHANGE_P0 has to be zero in order to be used together with the momentum profile that was first obtained with single bunch tracking?
Thanks.
Regards
Wei Hou
Re: Problems on using FTRFMODE
Posted: 16 Jun 2023, 13:12
by michael_borland
Wei-Hou,
Sorry, I didn't notice that you were loading an energy profile.
There does seem to be a bug in the twiss computation for this case. I'll fix it for the next release. The tracking results should be fine.
--Michael
Re: Problems on using FTRFMODE
Posted: 16 Jun 2023, 18:33
by WEI-HOU
Hello Michael,
Yes, Twiss parameters of the beam ( betaxBeam, etc) looks fine.
Thanks, keep me posted.
Regards
Wei Hou