How to add synchrotron motion in DA tracking

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duanz
Posts: 46
Joined: 30 May 2009, 01:50

How to add synchrotron motion in DA tracking

Post by duanz » 27 Mar 2011, 22:23

Hello, Michael,
I wonder how to add synchrotron motion in DA tracking, since in my case the synchro-betatron resonance might be important for off-momentum particles. However, whether or not I set the value of RF cavity voltage, the DA tracking results are the same. And I notice in the given examples RF cavity is not defined in the lattice of PAR used in DA tracking.

Thanks!

Zhe, Duan

michael_borland
Posts: 1735
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: How to add synchrotron motion in DA tracking

Post by michael_borland » 04 Apr 2011, 11:46

Duan,

There should be no issue adding SR motion to DA tracking. Just insert an RFCA element and set the voltage, frequency, and phase. It is probably also a good idea to include synchrotron motion with the SREFFECTS element.

Be sure to set the frequency precisely, otherwise, you'll get energy offsets. E.g., 500 MHz is not good enough if it is really 499.9987 MHz.

I've attached an example.

--Michael
Attachments
dynamicApertureWithSynchMotion.tar.gz
(2.46 KiB) Downloaded 5013 times

xhs05
Posts: 30
Joined: 29 Nov 2012, 21:43

Re: How to add synchrotron motion in DA tracking

Post by xhs05 » 13 Feb 2013, 10:14

Hi, Michael,

In your example, there is no 'rf_setup' in the '.ele' file. Is RF cavity taken into calculation in this case?

I'm trying to do a full 6-d tracking in my design. But I found that it is difficult to include the RF cavity correctly.

When I use 'rf_setup', it seems that the equilibrium phase is about 180 degree which not correct in my case. The momentum compaction factor in my case is negative. So I think that the phase of cavity should be around 0 degree. I don't know how to set it up.

But if I don't include 'rf_setup', it looks like RF cavity is not taken into consideration.

My files is attached.

Could you help me to do the full 6-D tracking correctly? Thank you!

Regards,
Haisheng Xu
Attachments
lat_3_6mring_fineDrift.lte
(2.83 KiB) Downloaded 454 times
run.ele
(1.03 KiB) Downloaded 458 times

michael_borland
Posts: 1735
Joined: 19 May 2008, 09:33
Location: Argonne National Laboratory
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Re: How to add synchrotron motion in DA tracking

Post by michael_borland » 13 Feb 2013, 17:56

Haisheng,

It seems rf_setup doesn't work for alpha<0 . I'll have to fix it in the next release.

Meanwhile, you can set the parameters in the lattice file. See the attachment. I fixed three things: (1) Set ISR1PART=0 on all elements. (2) Removed SREFFECTS. You don't need it since you are getting synchrotron radiation from the individual elements. (3) Set rf frequency using h*beta*c/C, which is important since beta is close enough to 1.

--Michael
Attachments
lat_3_6mring_fineDrift.lte
(2.86 KiB) Downloaded 494 times

xhs05
Posts: 30
Joined: 29 Nov 2012, 21:43

Re: How to add synchrotron motion in DA tracking

Post by xhs05 » 13 Feb 2013, 22:50

Thank you so much, Michael! Your explanation is quite clear and helpful!

By the way, I find another strange thing when I use the file you modified.

If I use the following command:

elegant run.ele
sddsplot run-001.w1 -col=Pass,Cdelta

I find that the Cdelta is oscillating with amplitude about 10^-5.

I guess that it is the numerical error, isn't it?

Regards,
Haisheng Xu.

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