Including space charge effect

[alexanatoly]

Hi, I would like to include space charge effect in the tracking simulation.

Please, could you help me to understand how I can do it ?

I followed the example give at : https://github.com/ocelot-collab/ocelot/blob/master/demos/ebeam/space_charge.py. but could not understand how the space charge effect is implemented.

I am using a small example file generated by ASTRA code and loading it in Ocelot.

Any help will be greatly appreciated.

Thanks. Alex

[alexanatoly]

Hi, I included the following lines for Space-Charge effect

sc1 = SpaceCharge() sc1.nmesh_xyz = [63, 63, 63] sc1.step = 1 navi = Navigator(lat) navi.add_physics_proc(sc1, lat.sequence[0], lat.sequency[-1])

Is the above is correct ?

Also, how to decided the mesh size ... why 63 ?

Thanks, Alex

[sergey-tomin]

Hi, if you want to apply Space Charge (SC) to the whole lattice, it looks okay. However, you need to determine how frequently you should apply SC to achieve the best accuracy. This is specified in the 'Navigator' class, where the default Navigator.unit_step is 1 m. If the beam energy is low (5-50 MeV), I would recommend using 0.01 m or even lower in some cases. Also, please remember that we can achieve good agreement with ASTRA for beam energies of 5 MeV and higher. If the beam has lower energy, I would recommend using ASTRA. If the beam is accelerated, you can use two or more SC objects. For example, for low energy, you can set sc1.step = 1 (SC will apply with step navi.unit_step * sc1.step m), and then for accelerator sections with high energy, you can set sc2.step = 5 or a similar value, and continue in this manner. It will speed up calculations without a lost of accuracy.

[alexanatoly]

Hi @sergey-tomin, thanks for explaining in detail. Somehow I missed your reply (sorry for it). My electron beam energy range is (10 MeV < energy < 1000 MeV). By the way, I must say that you have developed and made available to everyone a very nice beam dynamics code.