Simulation of 200 MHz RF cavities. 11 cells preliminary results Alexej Grudiev 20/04/2016

HFSS setup: 3D model from Ton Port 6 Port 5 Port 4 Port 3 Port 2 Port 1

Comparison measurements vs CST MS vs HFSS Very good agreement between CST MS and HFSS for S-parameters

HFSS: Eigenmode. Mesh and E-field of f0=628.5 MHz mode PML PML PML PML

HFSS: Eigenmodes: Ez (red), Ey (blue)

HFSS eigenmode: Modes parameters table, 2nd order tetr HFSS eigenmode: Modes parameters table, 2nd order tetr., 12 iterations (~10% error in R/Q) f [MHz] Q R/Q [linacOhm] Z [Ohm] 1 620.2 160 3.2 256 2 622.3 5891 0.055 162 3 623.0 17351 13.85 120156 4 624.5 14359 0.91 6533 5 625.2 518 29.3 7589 6 626.9 6451 15.28 49286 7 628.6 473 29.43 6960 8 631.0 57 8.41 240 9 631.4 261 5.55 724 10 634.4 445 0.23 51 Definitions: R/Q = Vz2/ωU Circuit impedance Z=R/Q*Q/2

Plane wave excitation setup: dYpw=1mm CompMagE in log scale: f=630MHz

E-field on axis with PW excitation: dYpw = 1mm; f=630MHz

E-field on axis with PW excitation: dYpw = 1mm; f=622 E-field on axis with PW excitation: dYpw = 1mm; f=622.86MHz (Highest Q-factor) 10π/11-eigenmode f0=623.0MHz Q = 17400

CST wake setup 3D model from Ton Mesh is good but still might be not good enough to describe narrow band 200 MHz rejection filter. So 200 MHz impedance might be different from FEM codes or measurements

CST wake, longer wake

CST impedance (FFT, cos^2 filter) df = 1/Tmax=c/s_max =3e8/300 = 1 MHz, better

Comparison of Re{Zl} between HFSS eigenmode, HFSS plane wave and CST wakefield