Dear Michael,
some undulators/wigglers may have a built-in gradient - alternating for C-shaped poles with doubled period of the gradient or ~constant (for micro-machined poles attached to large monoblocks of permanent magnets). Iis it possible to model such insertion devices...
Thank you very much
wiggler with Q-focusing
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michael_borland
- Posts: 1959
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
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Re: wiggler with Q-focusing
Alexei,
There are several options for modeling "unusual" wigglers. One straightforward approach is to model the wiggler as a series of bending magnets, using the makeWigglerFromBends script that is included with elegant; it should be straightforward to modify this to include gradients of different periodicity as you described.
Another approach is to make a kick-map, which can be done with programs like RADIA and used with elegant's UKICKMAP element. You could make a kickmap for a single wiggler period and then use it repeatedly.
You could also use an approach based on harmonic analysis of the wiggler field along with the CWIGGLER or GFWIGGLER elements.
My suggestion is to use the first approach. UKICKMAP and GFWIGGLER aren't designed to give you details on things like time of flight, which is probably important for a linac application. CWIGGLER is very slow. CWIGGLER and GFWIGGLER can be hard to configure correctly.
--Michael
There are several options for modeling "unusual" wigglers. One straightforward approach is to model the wiggler as a series of bending magnets, using the makeWigglerFromBends script that is included with elegant; it should be straightforward to modify this to include gradients of different periodicity as you described.
Another approach is to make a kick-map, which can be done with programs like RADIA and used with elegant's UKICKMAP element. You could make a kickmap for a single wiggler period and then use it repeatedly.
You could also use an approach based on harmonic analysis of the wiggler field along with the CWIGGLER or GFWIGGLER elements.
My suggestion is to use the first approach. UKICKMAP and GFWIGGLER aren't designed to give you details on things like time of flight, which is probably important for a linac application. CWIGGLER is very slow. CWIGGLER and GFWIGGLER can be hard to configure correctly.
--Michael
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alexei_sav
- Posts: 8
- Joined: 28 Oct 2013, 18:25
Re: wiggler with Q-focusing
Dear Michael, thanks for your so comprehensive and helpful replies.
Regarding the WIGGLER element.
Is my understanding correct that this is the only "wiggling" element resolving accurately the longitudinal structure of a (micro)bunch and the # of poles is always exactly half of number of periods...
Thanks again.
Regarding the WIGGLER element.
Is my understanding correct that this is the only "wiggling" element resolving accurately the longitudinal structure of a (micro)bunch and the # of poles is always exactly half of number of periods...
Thanks again.
-
michael_borland
- Posts: 1959
- Joined: 19 May 2008, 09:33
- Location: Argonne National Laboratory
- Contact:
Re: wiggler with Q-focusing
Alexei,
The CWIGGLER element is the most accurate approach for 6D tracking. The LSRMDLTR (laser modulator) element is also accurate for 6D tracking, and unlike the CWIGGLER element you don't need to do the harmonic analysis. Finally, using makeWigglerFromBends is good for 6D tracking.
The WIGGLER element is implemented as a first-order matrix, so many details will not be included. The number of poles can be even or odd. In the case of an odd number of poles, the end poles are half strength so there is no net deflection. In the case of an even number of poles, the end poles are half-length but jump to (fall from) full strength to zero instantaneously.
--Michael
The CWIGGLER element is the most accurate approach for 6D tracking. The LSRMDLTR (laser modulator) element is also accurate for 6D tracking, and unlike the CWIGGLER element you don't need to do the harmonic analysis. Finally, using makeWigglerFromBends is good for 6D tracking.
The WIGGLER element is implemented as a first-order matrix, so many details will not be included. The number of poles can be even or odd. In the case of an odd number of poles, the end poles are half strength so there is no net deflection. In the case of an even number of poles, the end poles are half-length but jump to (fall from) full strength to zero instantaneously.
--Michael