Wake-fields simulations and Test Structure G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Outline Baseline geometry Material properties GdfidL simulations Direct measurements of the transverse long-range wake-fields at FACET facility G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF Outline Baseline geometry Material properties GdfidL simulations Direct measurements of the transverse long-range wake-fields at FACET facility G.De Michele-A.Grudiev BE-RF
Baseline structure and HOM damping Iris radius 2.35mm WG cross section 11x6.66mm WG length 90mm G.De Michele-A.Grudiev BE-RF
Baseline structure and HOM damping SiC cross section 1x1 to 5.6x5.5mm SiC length 30mm+10mm flat Distance tip_SiC-structure_axis 50mm G.De Michele-A.Grudiev BE-RF
Baseline structure and HOM damping Very broad band absorption of the wake-fields Reflection below -30dB for TE10 mode and below -20dB for TE01 mode A.Grudiev, W.Wuensch in Linac10 Conference Design of the CLIC main linac acc. Struct. for CLIC CDR G.De Michele-A.Grudiev BE-RF
Baseline structure and HOM damping Double-feed coupler cell with a standard X-band WR-90 width X band, WR-90, 8.2 to 12.4, 0.900 x 0.400 inch (22.86x10.16mm) From 6.66mm to 10.16 we will need a tapered WG G.De Michele-A.Grudiev BE-RF G. De Michele
Baseline structure and HOM damping Coupler similar to the regular cell geometry Minimum quadrupolar kick from the fundamental mode Signals back from WG couplers damped on the load if magic-T present Tapering provides detuning of HOM G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Outline Baseline geometry Material properties GdfidL simulations Direct measurements of the transverse long-range wake-fields at FACET facility G.De Michele-A.Grudiev BE-RF
EM materials properties (T.Pieloni) G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Waveguide method High frequency EM characterization: the intersection of the surfaces with the measured S21 yields the possible solutions. Often one obtains the uniqueness of the solution with only two constrains furnished from the complex S21. Imaginary S21 at 10.5 GHz Courtesy C. Zannini, R. Zennaro, T. Pieloni ESK (Germany) type sample shape (mm) εr (10.5 GHz HFSS) (10.5 GHz CST) (28 GHz CST) EKASIC F SiC L49xW49xH10 11.2+j 1.06 (tanδ=0.095) 11.2+j 1.03 (tanδ=0.092) 11.0+j 0.88 (tanδ=0.080) G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF Coaxial method In collaboration with C. Zannini ESK (Germany) type sample shape (mm) εr (9 GHz CST) EKASIC F SiC d=1.32 D=4.08 12.0+j 1.08 (tanδ=0.090) G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF Coax and WG methods G.De Michele-A.Grudiev BE-RF
Cutoff limit and new geometry New geometry has higher cutoff (around 25GHz) Easy machining Series production in order to evaluate chemical treatment and heat treatment In the ranges where S11<1 has been found a really good match between O.C. and S.C. with TL methods (by taking into account also air-gaps). G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Future work Machining of the new samples Measurements (EkasicF, EkasicP, CerasicB1) until 30GHz: HOM-free up to 25GHz Tolerances study on coaxial/sample variations on scattering parameters. Investigation of influence of chemical and heating treatments on the properties of materials G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Outline Baseline geometry Material properties GdfidL simulations Direct measurements of the transverse long-range wake-fields at FACET facility G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF GdfidL simulations The electric current source density defined by a Gaussian bunch (6z), moving at the speed of light along the beam line GdfidL can compute with dispersive dielectrics but does not work very well and is quite CPU-intensive ( W. Bruns, 16.03.2011) A constant value of the effective conductivity is assumed by fixing a frequency and the losses are specified by the loss tangent G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF GdfidL simulations A beam with bunch length z =1.2mm is driven along the beam pipe with a transverse offset of 0.5mm G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF GdfidL simulations PEC PMC y x Position of the wake integration path Source charge G.De Michele-A.Grudiev BE-RF G. De Michele
G.De Michele-A.Grudiev BE-RF Future work New load design if we want to stick to EkasicF Choose another material with higher tanD: possible candidates could be CerasicB1 or EkasicP. In this case the present geometry will be fine. To be confirmed! Finally to model wake-fields of the structure with loads (modal sum) and to check if within beam dynamics constraints G.De Michele-A.Grudiev BE-RF
G.De Michele-A.Grudiev BE-RF Outline Baseline geometry Material properties GdfidL simulations Direct measurements of the transverse long-range wake-fields at FACET facility G.De Michele-A.Grudiev BE-RF
Facility for Advanced aCcelerator Experiment Test FACET provide an excellent opportunity to make direct beam-based long-range wake-field measurements of CLIC accelerating structures. PROPOSED LOCATION Layout of the ASSET facility G.De Michele-A.Grudiev BE-RF G. De Michele
Prototype structure for wake-fields measurements Advantages: Removable disks Removable loads Possibility to put WFM Pick-ups Optical ports Clamped Al cells Pick-ups Transition Simple vacuum tank WFM Optical ports Removable loads 1m G.De Michele-A.Grudiev BE-RF G. De Michele
Future plans-schedule (W.Wuensch) Run 1: 16 June to end August For preparing installation and for being able to do later tests. Basic check of beam line equipment, for example BPM readout exercises Arrange a few nighttime checks, adding some known deflections etc., to make sure the optics downstream of the ASSET position is well understood for later experiment Run 2: Two month run starting in January or February 2012 Positrons will be commissioned at this stage Redo an H60 wake-field measurement as a practice run. Time can probably found during night shifts Install structure during summer Run 3: Starts September-October 2012 to November/December Installation of our test structure Test during dedicated runs G.De Michele-A.Grudiev BE-RF