PS Longitudinal Impedance Model Update B Popovic 28022019

PS Longitudinal Impedance Model Update B. Popovic 28/02/2019 1

Past PS Longitudinal Impedance Model Presentations • Long. Limit. With LIU-PS RF Upgrades and Mitigation Strategy • • SPS Injection Losses Review • • https: //indico. cern. ch/event/672967/contributions/2753563/ PS-BD-WG #6 • • https: //indico. cern. ch/event/750790/contributions/3108016/ https: //indico. cern. ch/event/678530/contributions/2779037/ PS-BD-WG #1 • https: //indico. cern. ch/event/662292/contributions/2704441/ 2

Updates to the PS Longitudinal Impedance Model • Currently Installed Elements Modeled KFA 04 Kicker (Modeled from Old 2 D Drawings) • • Future Elements that have been Studied Vertical Beam Gas Ionization (BGI) Ralentisseur (Analysis by L. Teofili)* PS Injection Bumper Sections Modified KFA 45 • • • New, Larger, Ferrites * See for results: https: //indico. cern. ch/event/764129/contributions/3171805/ 3

KFA 04: Model 2 D CAD Drawings CST Model 4

KFA 04: Wakefield Results • See a similar response as the other kickers modeled (KFA 45, KFA 79 etc. ) • Broadband impedance with a few peaks (most likely tank modes) 5

Vertical BGI • Motivation: Impedance of a new object needs to be checked • Past issues with LHC BGI • Heating & impedance concerns • Designer contacted IWG early in the design process • Thanks BE-BI-BL! • Initial design study showed room for improvement • Addition of tapers to reduce impedance From: https: //indico. cern. ch/event/775257/contributions/3222637/ 6

PS Injection Bumper Sections • SD 40 Motivation Potential non-broadband impedance contributions • SD 41 • SD 43 • SD 44 • Overview of Simulations Inconel sections only have broadband impedance at these frequencies (< 1. 5 GHz) Offset steps result in no resonances at these frequencies Some resonances present due to the valve (SD 41) • Inconel Section Trapped modes due to aperture mismatches Already accounted for in the PS long. impedance model From: https: //indico. cern. ch/event/797962/contributions/3316173/ 7

• Necessary to check for trapped modes due to aperture mismatches • Such as in the Inconel section Long. Imped. (ohms) PS Injection Bumper Sections: SD 40** Freq. (MHz) ** Worst-case scenario of the four SD sections Aperture mismatch (Potential Cavity) Stepdown Transition (Aperture Mismatch) Inconel Section From: https: //indico. cern. ch/event/797962/contributions/3316173/ 8

KFA 45 Ferrite Enlargement • Complete KFA 45 Model Test study of single cell 32 cells total in the KFA 45 Entire KFA 45 model is a huge simulation • • • Presented at PS-BD-WG #1 Single Cell Models Enlarged Current From: https: //indico. cern. ch/event/764129/contributions/3171804/ 9

KFA 45 Ferrite Enlargement • Enlargement of ferrite causes slight downward shifts in frequency and variation in peaks • Since most of the impedance is broadband except for tank modes, negligible change in impedance Long. Imped. (ohms) Single Cell Wake Field Simulation KFA 45 Wake Field Simulation Freq. (MHz) From: https: //indico. cern. ch/event/764129/contributions/3171804/ 10

Further Elements to add • • 20 MHz & 200 MHz Cavities Septums • • Remaining Kicker • • KFA 28 Beam instrumentation equipment • • See next slide for comments Pick-ups Vacuum elements • Flanges, bellows, transitions, etc. 11

Comments on Septums • • • BFA 9 SMH 16 BFA 21 To be removed (Removal of Continuous Transfer System)* Replaced with straight beam pipe • • • SEH 23 SMH 26 SEH 31 To be removed (Removal of Continuous Transfer System)* Replaced with straight beam pipe • • • SMH 42 To be replaced by a new septum** Simulations of new SMH 42 awaiting measurement confirmation • • Difficulties in modeling laminated steel sections SMH 57 *https: //edms. cern. ch/ui/file/1981131/0. 1/PS-LJ-EC-0007 -00 -10. pdf **https: //edms. cern. ch/document/1856808/0. 1 12

Reference: Indico Pages • Vertical Beam Gas Ionization (BGI) • • Ralentisseur (Analysis by L. Teofili) • • https: //indico. cern. ch/event/764129/contributions/3171805/ PS Injection Bumper Sections • • https: //indico. cern. ch/event/775257/contributions/3222637/ https: //indico. cern. ch/event/797962/contributions/3316173/ New KFA 45 Ferrite Sizes • https: //indico. cern. ch/event/764129/contributions/3171804/ 13

Questions? 14

Extra Slides 15

Vertical BGI From: https: //indico. cern. ch/event/775257/contributions/3222637/ 16

PS Injection Bumpers: SD 44 • Inconel Chamber • • • 146 x 68 – 190 x 70 – 146 x 68 Ellipse – Hippodrome Ellipse Offset Step • • Hippodrome (MU 43)-Ellipse 190 x 70 – 146 x 70 Note the poor meshing at Inconel. . . Only interested in the offset step. From: https: //indico. cern. ch/event/797962/contributions/3316173/ 17