laser modulation in helical undulator

[zzhang]

Hi,
I want to simulate laser modulation in a helical undulator. But LSRMDLTR only includes planar one. Any suggestion for this? Is it possible to add an element to deal with laser modulation in helical undulator?
Thanks.
Zhen

[michael_borland]

This is possible by adding expressions for a helical device to the code. The tricky part is modeling the wiggler fields with proper end terminations. I wonder if you are familiar with a reference that gives expressions for this?

--Michael

[zzhang]

Michael,

I find a reference that gives the fields of helical wiggler by leading terms (A2 ans A3 in the attached paper). A3 is in rectangular coordinates. Could you please help us add this field to the code?

Thanks.

Zhen

[michael_borland]

Zhen,

That's helpful, but unfortunately they don't give a scheme for tapering at the ends. They mention that it is needed. I'll talk to some of my colleagues here and see if they have any ideas for how to do it.

--Michael

[zzhang]

Hi Michael,
Are there any new functions to simulate the laser modulation in a helical undulator by now? LSRMDLTR only includes planar one.
Thanks.
Zhen

[michael_borland]

Zhen,

My colleague Yipeng Sun is going to work on this. I can't promise it will be done very soon, but it should appear in a release in the next few months.

--Michael

[zzhang]

Hi Michael,

Is there anything new about this topic? Is it possible to simulate the modulation in helical undulator now?

Thanks.

Zhen

[michael_borland]

Zhen,

We hope to have it in the next release, perhaps in the next month or so.

--Michael

[michael_borland]

Zhen,

Version 31.0 has been released, with the ability to model helical undulators in LSRMDLTR. Please see the
manual for details. Feedback is welcome, as our testing was pretty basic.

--Michael

[zzhang]

Hi Michael,

I have tried the new version and thanks for your work. Now I have a new problem. It seems that the laser in the undulator only have one polarization direction. However, when it is helical undulator, I want to rotate the laser polarization direction to (\hat{x}+\hat{y})/\sqrt(2), so that there will be interaction in two directions. Can I do this in the current version?

Thanks.

Zhen