Hi,
I am trying to understand better the LASER_PHASE parameter for the LSRMDLTR element. I can use this parameter to shift the phase of the laser, but have not been able to work out how the zero-phase is defined. Also, how does this relate to the TIME_OFFSET parameter for the external time-dependent modulation of the laser beam?
Thanks,
Ian
LSRMDLTR reference phase
Moderators: cyao, michael_borland
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- Location: Argonne National Laboratory
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Re: LSRMDLTR reference phase
Ian,
The phase of the laser field is calculated as phi=k*(z-L/2) - omega*t + phi0, where L is the length of the undulator, t is the time coordinate of the particle, phi0 is the phase specified. Unfortunately, I didn't use (t-tc), so it a bit confusing to set phi0. I'd suggest using LASER_PHASE of omega*L/(2*c) + dphi, where dphi is the desired phase.
For the profile offset, the time coordinate used for the lookup table is t - tfid + tOffset, there tfid is the arrival time of the fiducial particle at z=L/2 and tOffset is the TIME_OFFSET parameter.
Hope this helps.
--Michael
The phase of the laser field is calculated as phi=k*(z-L/2) - omega*t + phi0, where L is the length of the undulator, t is the time coordinate of the particle, phi0 is the phase specified. Unfortunately, I didn't use (t-tc), so it a bit confusing to set phi0. I'd suggest using LASER_PHASE of omega*L/(2*c) + dphi, where dphi is the desired phase.
For the profile offset, the time coordinate used for the lookup table is t - tfid + tOffset, there tfid is the arrival time of the fiducial particle at z=L/2 and tOffset is the TIME_OFFSET parameter.
Hope this helps.
--Michael
Re: LSRMDLTR reference phase
Michael,
So if I understand correctly, the phase of the laser is not necessarily fixed with respect to the time envelope? Is this the case? ie if I set the LASER_PHASE and TIME_OFFSET to particular values and then track a different bunch through the element, this could give a different phase wrt to the peak of the time envolope due to the different value for tfid?
thanks,
Ian
So if I understand correctly, the phase of the laser is not necessarily fixed with respect to the time envelope? Is this the case? ie if I set the LASER_PHASE and TIME_OFFSET to particular values and then track a different bunch through the element, this could give a different phase wrt to the peak of the time envolope due to the different value for tfid?
thanks,
Ian
-
- Posts: 1933
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: LSRMDLTR reference phase
Ian,
Yes, that's correct.
--Michael
Yes, that's correct.
--Michael
Re: LSRMDLTR reference phase
MIchael,
I have been trying to carry out jitter simulations using the LSRMDLTR element, fixing the phase of the laser with respect to the time envelope. To do this I was tracking 2 bunches, the first to act as the fiducial bunch and then apply errors to the linac for the second bunch. When I try this the time envelope remains constant between the two bunches, but the phase of the laser changes. Is there a way to fix the phase? I've attached the .ele and error files I've used as reference, and also a plot showing the longitudinal phase space for the two bunches at the end of the linac.
thanks again,
Ian
I have been trying to carry out jitter simulations using the LSRMDLTR element, fixing the phase of the laser with respect to the time envelope. To do this I was tracking 2 bunches, the first to act as the fiducial bunch and then apply errors to the linac for the second bunch. When I try this the time envelope remains constant between the two bunches, but the phase of the laser changes. Is there a way to fix the phase? I've attached the .ele and error files I've used as reference, and also a plot showing the longitudinal phase space for the two bunches at the end of the linac.
thanks again,
Ian
- Attachments
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- longitudinal phase space comparison
- modulated_bunches.png (10.09 KiB) Viewed 2024 times
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- PVB.003.sdds
- error definitions
- (203.85 KiB) Downloaded 163 times
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- slicing_PVBI.003.ele
- elegant input file
- (1.34 KiB) Downloaded 165 times