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Document Conversion from Alternative Input Parameters #581
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It might be good idea to give the input electron beam as one of the options sigma_x, sigma_y, where, x & y are transverse coordinates. sigma_tau, represent longitudinal length of the electron beam. emit, represent emittance of the beam gamma, is the beam energy sigma_gam, is energy spread chirp, amount of chirp in the electron beam phase-space Q represent total charge of the electron beam npart represent number of particles. Such representation of input electron beam is much clear and easy to give input. |
We might need to explicitly mention in the docs how to calculate from these common inputs into our distributions? X-ref: #580 |
Dear everyone (@n01r @ax3l @cemitch99), thank you for considering the request. It will be very helpful. |
Hi everyone @n01r @ax3l @cemitch99 sorry for bothering again. Just curious to know when flexible input parameters capability will be available to use ? Thank you. |
Hi @zhangli28, is there anything missing fpr you in making the conversion to your input parameters right now? Please let us know. :) We will implement more input methods soon but that should not stop you from running simulations already. Let us know if there are still things that are unclear! 😊 |
Hi @n01r , Thank you very much for answering every time. Please, see below what I was able to do so far
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Hi @zhangli28. You can obtain this information from the three values: sigma_tau, sigma_p, and the energy chirp. Let us assume that sigma_p is the uncorrelated relative momentum spread (dimensionless), and the energy chirp (call it h) is in units of 1/meter. Then, at values of relativistic beta ~ 1 (as in your case): emit_t = sigma_tau*sigma_p This comes from writing down the 2x2 covariance matrix in the longitudinal variables. Just be careful with the sign of alpha_t, because this depends on the sign convention used to define the energy chirp. |
Hi @zhangli28, I think I see the problem. You have the |
Ah, sorry @cemitch99, we answered at the same time. But your answer gets us further. 🙂 |
Hi @n01r and @cemitch99 , Thank you so much to both of you. You all are great guys. |
Hi @n01r @cemitch99 , I have some doubt about the chicane set up used in the example file "input_chicane.in", whose values are taken from the reference https://www.desy.de/csr/ I searched about my doubt on internet but not able to get it clear. So, I returned back to you. Please can you see the attached pdf file (ImpactX_Chicane_setup). Here I try to explain my question. If these questions can be answered, I am almost ready to do what I am trying from many days. Thank you. |
Hi @zhangli28, when I look at the MAD-X input file for the DESY-Zeuthen chicane benchmark I can see the following
and from the schematics on the web page and in your PDF it seems to me that the 5 meters are the projected lengths in z-direction. But ImpactX is an s-based code which gives the length of elements as the actual path length. impactx/examples/chicane/input_chicane.in Line 33 in 08e55a2
@cemitch99 am I correct in assuming that this was the rationale behind these parameters?
What else is blocking you from doing what you intended? Or what did you intend to do? |
Hi @n01r, that's exactly right. Regarding the magnets themselves: the value of ds in the ImpactX input file is the arc length of the magnet, while the schematic on the web page gives the projected length along the z-direction. Some geometry will show you that the two correspond. |
Hi @n01r @cemitch99 , thank you so much for your help. Now, everything is there to start my run, however, one thing is not looking correct in the example file and that is the value The length of the magnet is 0.5 m. If we calculate like |
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Hi @n01r, |
Hi @n01r , following the the MAD-X input file for the DESY-Zeuthen chicane, I did as follows
but this gives me |
Hi @zhangli28, Yes, it looks like the result you quote above for LBS is correct. Attached is a figure illustrating the geometry. Thanks for pointing out this apparent 10^(-4) relative error in ds, which will be addressed. |
Hi @n01r, @cemitch99 very very thanks to both of you. Without your help it was not possible for me to understand things clearly. Cheers, |
Hi @n01r, @cemitch99 , today, before running my new test script, just to be sure that everything is working fine, I once again made test runs of the examples given for the chicane: The python script
The same error message appear when I tried my new input script Do you have any suggestions how to fix this. |
Hi @zhangli28, the reason this is failing at runtime is that you likely activated a conda environment (and/or a specific set of HPC software modules) when you compiled ImpactX - but then did not load it again at runtime. |
Hi @ax3l I removed the
and then I install as
then, I copied the impactx* executable in my working directory and uses the command |
@zhangli28, what @ax3l was referring to was that not only do you need to have your modules loaded (ideally via a Can you confirm that all modules were loaded and paths were set? @ax3l, during the installation @zhangli28 had to specify |
@ax3l , @n01r
This means the error |
Hi @n01r @cemitch99 @ax3l , I made the build directory using the command
Now, suppose I used the command below for installation.
After some time, if I wan to change the installation type and wan to use
can I do it without re-building ? In general, can I use any of the command below as many times, and in any order, without any need to touch the
sorry for so many questions. I hope it will be ending soon. |
Hi @n01r ,
I am trying to google search about this erro and if you get any idea of removing this error please let me know. Thank you. |
Hi @n01r @ax3l @cemitch99 , Maybe I am approaching towards the solution. This is because when I used the command
I got the following:
This means all the missing parts are there only need to link them properly. Do you have any suggestion how to do it ? Thank you. |
Hi @n01r , @cemitch99 @ax3l , Finally, starts running. Maybe the module ananconda3 is conflicting with the python modules in conda_env impactx-cpu. Thank so much to all of you. |
Dear ImpactX developers,
While using impactX, I feel that giving a electron beam input parameters is not very clear for the user. I suggest adding some additional features of loading electron beam as available in FBPIC code.
Thank you.
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