Return-Path: Received: from [178.24.5.94] (account huebl@hzdr.de HELO [192.168.178.22]) by hzdr.de (CommuniGate Pro SMTP 6.1.12) with ESMTPSA id 15679082 for picongpu-users@hzdr.de; Tue, 14 Feb 2017 23:04:45 +0100 Subject: Re: Laser pulse polarization To: picongpu-users@hzdr.de References: From: Axel Huebl Organization: HZDR Message-ID: <32fdb3dd-a488-3784-29a3-affa78817c18@hzdr.de> Date: Tue, 14 Feb 2017 23:04:44 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Exactly, every direction (plane) that is not set to --periodic is automatically absorbing (open). The only exception is the laser initialization plane, which activates it's absorbers after the LASER_INIT time has passed. Nevertheless, our open boundary conditions are rather rough and "stupid", adding PMLs there would be wonderful. Axel On 09.02.2017 16:11, Khikhlukha Danila wrote: > Hi Richard, > > Just to double check, I guess currently the boundary conditions for both > particles and fields are open, i.e. absorbing? > > > > Regards, > > Danila. > > > > *From:*picongpu-users@hzdr.de [mailto:picongpu-users@hzdr.de] *On Behalf > Of *Richard Pausch > *Sent:* Wednesday, February 08, 2017 12:55 PM > *To:* picongpu-users@hzdr.de > *Subject:* Re: [PIConGPU-Users] [PIConGPU-Users] [PIConGPU-Users] > [PIConGPU-Users] [PIConGPU-Users] [PIConGPU-Users] Laser pulse polarization > > > > Dear Bifeng Lei, > > thanks for the new plots. They helped me a lot. > > I suspect that your laser is partially reflected at the boundaries. > - Do you have “our” absorbing boundary conditions on? (No "—periodic 1 > 0 1" in submit.start) > - Is your transversal simulation length not much larger than your laser > spot-size? (cells in x |CELL_WIDTH_SI| / |W0_SI| > ~10 and cells in z > |CELL_DEPTH_SI| / |W0_SI| > ~ 10) > > If you answer both questions with yes, you might get some reflections > from the absorber that interacts with the (back) of you laser pulse. > > To avoid this, increase the transversal extent to contain more than > approximately 10-20 laser spot sizes. > > I hope this will solve your problem. > > Best, > Richard > > > Am 08.02.2017 um 12:06 schrieb Bifeng Lei: > > Dear Richard, > > I am not reduce the resolution. by setting |plt.imshow( ... , > interpolation="nearest"|) > > A 1D lineout plot on-axis. > > All best > Bifeng Lei > > On 02/08/2017 11:50 AM, Richard Pausch wrote: > > Hi Bifeng Lei, > > Okay - that looks fine (except that you time step is a bit short > for numerical stability in long simulation runs, better would be > ~1.12969e-16). > > Why does your picture only show one “imshow cell”/colored cell > per ~10-50 cells? > Did you reduce the resolution during analysis? > Might the transversal structures we see in the picture be an > aliasing effect? (can be avoided by setting |plt.imshow( ... , > interpolation="nearest"|) > > Could you please re-plot the picture in 1D, be selecting the > center x-position and plotting a lineout of the field along the > y-axis with a mark for each value. That would ease determining > if there are aliasing effects in the imshow picture. > > Best, > Richard > > Am 08.02.2017 um 11:37 schrieb Bifeng Lei: > > Dear Richard, > > Thank you so much for your reply. > > A 0.8um laser is used. The resolution is given as: > > dx and dz: 0.0743e-6m --> 0.8/0.0743=10.7 > > dy: 0.0443e-6m --> 0.8/0.0443=18 > > dt : 3.0e-17s > > By the way, is there a way to set the polarization angle > with respect to x/z-axis? > > All best > > Bifeng Lei > > > > On 02/08/2017 11:28 AM, Richard Pausch wrote: > > longitudinal resolution is too low? > > > > With best regards, > > Ph.D Bifeng Lei > > -- > > GSI Helmholtzzentrum für Schwerionenforschung GmbH > > Planckstraße 1 > > 64291 Darmstadt > > www.gsi.de > > > > Gesellschaft mit beschränkter Haftung > > Sitz der Gesellschaft: Darmstadt > > Handelsregister: Amtsgericht Darmstadt, HRB 1528 > > > > Geschäftsführung: > > Ursula Weyrich, Professor Dr. Karlheinz Langanke, Jörg Blaurock > > > > Vorsitzender des Aufsichtsrates: Staatssekretär Dr. Georg Schütte > > Stellvertreter: Ministerialdirigent Dr. Rolf Bernhardt > > ​ > > > > ​ > ​ > ​ > ​ > > ​ > -- Axel Huebl Phone +49 351 260 3582 https://www.hzdr.de/crp Computational Radiation Physics Laser Particle Acceleration Division Helmholtz-Zentrum Dresden - Rossendorf e.V. Bautzner Landstrasse 400, 01328 Dresden POB 510119, D-01314 Dresden Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey Prof. Dr.Dr.h.c. P. Joehnk VR 1693 beim Amtsgericht Dresden