How to add errors to a cryomodule

[Zhenbiao]

Hi,

I'm using elegant to simulate the misalignment of cryomodules. The cryomodule consists of 8 cavities. The definition of a module is as follows:

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L2_8CAVL : LINE=(CAVL_2,DCM2,CAVL_2,DCM2,CAVL_2,DCM2,CAVL_2,DCM2,CAVL_2,&
   DCM2,CAVL_2,DCM2,CAVL_2,DCM2,CAVL_2)
CM04 : LINE=(BEGCM04,DCM0,DCM1,L2_8CAVL,DCM3,MKQCM04,QCM04,CHVCM04,BBPMCM04,QCM04,DCM4,&
        ENDCM04)
CM05 : LINE=(BEGCM05,DCM0,DCM1,L2_8CAVL,DCM3,MKQCM05,QCM05,CHVCM05,BBPMCM05,QCM05,DCM4,&
        ENDCM05)
CM06 : LINE=(BEGCM06,DCM0,DCM1,L2_8CAVL,DCM3,MKQCM06,QCM06,CHVCM06,BBPMCM06,QCM06,DCM4,&
        ENDCM06)

I want to add the following errors: cryomodule misaligments, cavity misalignments wrt. CM, quadrupoles misalignments wrt. CM, BPM misalignments wrt. CM. The cryomodule is a line, not an element. How to add errors to a cryomodule composed of multiple elements? And how to add the cavity errors wrt. CM? The cavities and quadrupoles are inside the cryomodule. Is it the same as adding errors directly to the elements inside the CM like the following codes?

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&error_element name=QCM04, element_type=*QUAD*, item=DX, amplitude=150e-6, cutoff=2 &end
&error_element name=QCM04, element_type=*QUAD*, item=DY, amplitude=150e-6, cutoff=2 &end
&error_element name=QCM04, element_type=*QUAD*, item=TILT, amplitude=2e-3, cutoff=2 &end

Many thanks for any suggestion,
Zhenbiao Sun

[michael_borland]

Zhenbiao,

There are several ways to do this. In simple cases, you can use markers to define the start and end of the girders, then use a set of error_element commands for each girder. In addition, you can impart errors to individual elements, which are then taken relative to the girder component. This works because elegant by default adds the effects of multiple error_element commands for each element. I've attached an example.

A more complex simulation is available in the examples file. Look for NSLS-II-GirderMisalignment.

--Michael

[Zhenbiao]

Hi Michael，

Thanks for your reply. I encountered another issue. When I used the following code to add roll errors to the bends:

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&error_element name=*, element_type=*CSRCSBEN*, item=DX, amplitude=100e-6, cutoff=3 &end
&error_element name=*, element_type=*CSRCSBEN*, item=DY, amplitude=100e-6, cutoff=3 &end
&error_element name=*, element_type=*CSRCSBEN*, item=TILT, amplitude=0.5e-3, cutoff=3 &end

an error occurred:

error: can't misalign tilted bending magnet

How to add roll errors to the bends? In addition, is there a way to add pitch and yaw errors to elements such as bends, quadrupoles, and RFCW in elegant?

Zhenbiao

[michael_borland]

Zhenbiao,

I think you are using an old version of elegant. I you upgrade, you'll get better misalignment support. See the manual page for CSBEND, for example, for details about the methods available.

--Michael

[Zhenbiao]

Hi Michael,

I was using Elegant 2020 previously, and I've now updated to the latest version. According to the latest manual, it is possible to add pitch and yaw errors to quadrupoles and bends. That's great! But for RFCW and MONI elements, it is still not possible to directly add pitch and yaw errors.

Zhenbiao