Element ZTRANSVERSE

[xhs05]

Hi Michael,

I'm using elegant 33.0.2.

I've found that the ZTRANSVERSE element doesn't work well when I use Pelegant to simulate the transverse single-bunch instability. The problem is that no output wake data and the beam moment data when I set {wakes="trwake.sdds"] in the ZTRANSVERSE element.

However, the output file "trwake.sdds" shows when I run the same script by elegant instead of Pelegant. Would you like to double check whether this is a bug or not?

Thank!

Regards,
Haisheng

[michael_borland]

Haisheng,

The parallel version doesn't have the feature of dumping the wake output. The manual should mention this, but it was overlooked.

The reason is that wake output is considered a debugging feature.

--Michael

[xhs05]

Hi Michael,

Thanks for the clarification!

Regards,
Haisheng

[guenzel]

This is actually not a response to the problem of xhs05, but another problem i encountered using ZTRANSVERSE. Should I better open a new topic ?

Anyway, I also want to study instabilities with the element ZTRANSVERSE, and as first approach I set up a very simple periodic structure (a ring) consisting of a ILMATRIX, a CAVity and broadband resonator given by ZTRANSVERSE. I used as broadband parameters R=1e6Ohm/m , f_{reso}=11MHz and Q=1.

Find here some extracts from the elegant (parallel version) output:
This is elegant 28.1.0, Jul 24 2015, ...
...
ZTRANSVERSE,CHARGE=1.602E-10,BROADBAND=1,RS=1.0E6,Q=1.,FREQ=11.E06,BIN_SIZE=0

In the manual it was written "(use 0 for autosize)", for BIN_SIZE, however I got the following error message.

error: bin_size must be positive for ZTRANSVERSE element


In the following I tried a non-zero BIN_SIZE, but elegant commented that my BIN_SIZE is too large and rescaled it to values in the area ~1e-12 -- 1e-13 and complained about the necessary small BIN_SIZE.

Actually I not only tried FREQ=11.E06, also even FREQ=11.E09 whiich seems to a rather realistic BBR-frequency for the description of the total transverse impedance of a synchrotron light source.

So I wonder how to use ZTRANSVERSE to include a realistic trans BBR in a ring. Could you help me out ? Consider that I've just started using ELEGANT.

Thank you
Thomas Guenzel

[michael_borland]

Thomas,

Here's an example of using ZLONGIT for a broad-band impedance. ZTRANSVERSE should be very similar. Let me know if this doesn't help resolve the difficulties.

--Michael

[guenzel]

Dear Michael,

thank you very much.

I will try out.

Regards,
Thomas