18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip.-Ing. Cong Liu | 1 Various approaches to electromagnetic.

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1 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip.-Ing. Cong Liu | 1 Various approaches to electromagnetic field simulations for RF cavities Cong Liu

2 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 2 Outline Cavity modeling in CST MICROWAVE STUDIO® Field simulation in time domain Field simulation in frequency domain Detection of the eigenmodes in the transmission spectrum Future work

3 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip.-Ing. Cong Liu | 3 SPL Cavity Modeling in CST MICROWAVE STUDIO®

4 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip.-Ing. Cong Liu | 4 Field Simulation in Time Domain Field probe Field excitation

5 Field Simulation in Time domain Probe Time Signal 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip.-Ing. Cong Liu | 5 15 10 5 0 -5 -10 -15 0 50 100 150 200 250 300 Time / ns

6 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 6 Field Simulation in Time Domain Using the Fourier transform => Transmission spectrum dipole passband 70 60 50 40 30 20 10 0 -10 -20 monopole passband 0.5 1 1.5 2 2.5 3 Frequency / GHz

7 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 7 Field Simulation in Frequency Domain Calculation of the resonance frequencies and the corresponding eigenmodes

8 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 8 Field Simulation in Frequency Domain The TM010 Pi-mode for particle acceleration

9 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 9 Field Simulation in Frequency Domain The TM010 Pi-mode for particle acceleration

10 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 10 Detection of the Eigenmodes in Transmission Spectrum The modes of the TM010 band Result from time domain Result from frequency domain 90 80 70 60 50 40 30 20 10 690 692 694 696 698 700 702 704 706 708 710 Frequency / MHz Magnitude (db)

11 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 11 Detection of the Eigenmodes in Transmission Spectrum The modes of the TM110 band 10 0 -10 -20 -30 -40 -50 -60 -70 0.98 0.985 0.99 0.995 1 1.005 1.01 1.015 1.02 1.025 Frequency / GHz Result from frequency domain Result from time domain Magnitude (db)

12 18.05.2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Dip -Ing. Cong Liu | 12 Future Work Simulation with higher resolution by means of higher order curvilinear elements Detection of all higher order modes (HOMs) in the transmission spectrum up to 3 GHz Damping consideration for HOM-couplers

13 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 13 Cavity Simulations Particle accelerators -FLASH at DESY, Hamburg http://www.desy.de TESLA 1.3 GHz TESLA 3.9 GHz

14 Problem definition -Geometry 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 14 Elliptic Cavity with Couplers TESLA 3 rd harmonic 9-cell cavity including couplers

15 Problem definition -Accelerating field 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 15 Fundamental Mode TESLA 3 rd harmonic 9-cell cavity including couplers z EzEz Longitudinal electric field strength

16 Problem definition -Accelerating field 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 16 High Precision Field Calculations TESLA 3 rd harmonic 9-cell cavity including couplers Determine the accelerating -mode with high precision

17 Problem definition -Geometry -Task 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 17 Simulation Setup TESLA 3 rd harmonic 9-cell cavity including long beam tubes PEC boundary condition Search for the - mode field distribution Grid: CST – STUDIO SUITE ® 1 W

18 Problem definition -Geometry -Task 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 18 Parallelisation on Cluster Computer Distribution on 64 nodes ParMeTiS and VTK TESLA 3 rd harmonic 9-cell cavity including long beam tubes Search for the - mode field distribution Grid: CST - Studio Suite ®

19 Simulation results 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 19 Electric Field on Cavity Axis |E z | ExEx EzEz EyEy 585 409 cells, unsymmetric mesh

20 Simulation results 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 20 Higher Resolution 908 268 cells, unsymmetric mesh ExEx EyEy |E z | EzEz

21 Mesh has to be Symmetric Transversal grid information - Cut plane plots 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 21 Iris Equator unsymmetric mesh generation

22 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 22 Construction of Symmetric Mesh Symmetric mesh generation Coaxial coupler Higher order mode coupler (HOM) HOM Beam tube TESLA 9 cell cavity Idea: 1) Meshing performed only on ¼ of the model 2) Copy mesh to assemble the full information CST - Studio Suite ®

23 Mirror Symmetric Mesh Transversal grid information - Cut plane plots 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 23 Iris Equator symmetric mesh generation

24 Transversal Forces on Particles Simulation results -TESLA 3.9 GHz 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 24 ExEx z z FxFx FyFy EyEy c 0 B y c 0 B x Contributions to the force for a particle moving with speed of light along the axis

25 Integrated forces Integrated Forces 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 25 Quantity used to characterize the fields (kick factors)

26 Integrated forces Resulting Kick Factors 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 26 TESLA 3.9 GHz (lower resolution)TESLA 3.9 GHz Full: Upstream: Downstream: Full: Upstream: Downstream: 1 904 470 Cells 11 780 962 DOFs 3 282 467 Cells 20 370 322 DOFs

27 2014518 2014518 2014518 2014518 2014518 2014518 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Wolfgang Ackermann | 27 Summary / Outlook Summary: -Request for precise modeling of electromagnetic fields in resonant structures including small geometric details such as high power / HOM coupler -Geometric modeling with CST STUDIO SUITE ® -Kick factor calculation for TESLA 1.3 GHz and 3.9 GHz Outlook: -Detailed study of longitudinal and transversal fields for accurate beam dynamics simulations for SPL / ESS?

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