PS Impedance Model Update: KFA28 & BFA09...IWG#37 Branko K. Popovic 12 13 KFA28 : 3D Model from Paper Drawings IWG#37 Branko K. Popovic KFA28 Longitudinal Impedance 14 Mode at 1.19

PS Impedance Model

Update: KFA28 & BFA09Branko Popovic

30/01/20

IWG#37 Branko K. Popovic 1

Past PS Longitudinal Impedance Model Presentations

• PS-BD-WG #27

• https://indico.cern.ch/event/801198/contributions/3329723/

• Long. Limit. With LIU-PS RF Upgrades and Mitigation

Strategy


• SPS Injection Losses Review


• PS-BD-WG #6


• PS-BD-WG #1


2IWG#37 Branko K. Popovic

https://indico.cern.ch/event/801198/contributions/3329723/



Updated: Further Elements to add

• 20 MHz & 200 MHz Cavities

• Septums

• See later slides for comments

• Remaining Kickers

• KFA28

• KFA13/KFA21

• Transverse Feedback Kicker*

• Beam instrumentation equipment

• CODD Elements

• Vacuum elements

• Flanges, bellows, transitions, etc.

3

*https://indico.cern.ch/event/837716/

IWG#37 Branko K. Popovic

https://indico.cern.ch/event/837716/

Elements Covered in this Presentation

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum


Elements Covered






Background: Transition Piece in KFA Magnets*

• Added to new KFA45

• Piece was added to KFA13 & KFA 21 as well• Identical Units

• Need to re-simulate

• Use opportunity to use schematic solver as well

* https://indico.cern.ch/event/830722/contributions/3479602


https://indico.cern.ch/event/830722/contributions/3479602

KFA13/KFA21 Model with Transition Piece

Transition Pieces

• Piece was added to KFA13 & KFA 21 as well

• Needed to resimulate Wakefield result

• Use opportunity to use schematic solver as well


Background: Schematic Solver*

* https://indico.cern.ch/event/830722/contributions/3479602


https://indico.cern.ch/event/830722/contributions/3479602

Compare with Wakefield (Terminations Shorted)


KFA 13/21 Re-simulation: Conclusion

• Transition Piece:

• Mode at 50 MHz Disappears

• Higher frequency modes are heavily damped (especially 1100

MHz)

• Schematic Simulations

• Modes below 15 MHz are heavily dampened when shorted


Elements Covered






Short Commentary on Reference Files For Wire

Measurements of KFA28 and KFA09

• Both the KFA28 and BFA09 use large ferrite* sections

• Its not possible to generate a simulation model for the

ref file

• Cannot include the ferrites => They are an impedance

contribution that you are trying to measure

• No Ferrite => Extra resonance modes present that would be

damped away in the tank

• Must use numerical reference file

• Magnitude = Loss due to matching resistors

• Phase = Mechanical length

*8C11


13

KFA28 : 3D Model from Paper Drawings


KFA28 Longitudinal Impedance

14

Mode at 1.19 GHz

Mode at 1.51 GHz

Wire Simulation Modes


A Boundary Condition Error…

• 250 mm Diameter input/outputs to the device

D250 mm

fcTE11 = 900 MHz

fcTM01 = 1.176 GHz

Standard PS Beam Pipe

fcTE11 = 980 MHz

fcTM01 = 2.5 GHz

D250 mm to PS Beam Pipe

ST0377524_01


Elements Covered






BFA09: 3D Model from Paper Drawings

17

Pedestal Staircase


8C11 Ferrite 8C11 Ferrite

Simulations in Wire and Wakefield


Why the discrepancy between solvers above for both

elements?

• Reference file?

• Swept Magnitude and Phase… No Difference

• Ferrite Material Definition Differences between Solvers?

• Fundamentally the same at these frequencies

• Meshing?

• Different meshers but seem reasonable

• Boundary Conditions?

• This issue needs to checked; the large circular beam pipes

were used as ending the device instead of attaching the

smaller PS Beam Pipes

• Resimulate Wakefield Simulations of BFA09 & KFA28


Regarding Removing vs Disconnecting Staircase

Component

20

https://edms.cern.ch/ui/file/1981131/0.1/PS-LJ-EC-0007-00-10.pdf


https://edms.cern.ch/ui/file/1981131/0.1/PS-LJ-EC-0007-00-10.pdf

Elements Covered






Comments on Septums

• BFA09• Simulated

• SMH16

• BFA21• To be removed (Removal of Continuous Transfer System)*

• Replaced with straight beam pipe

• SEH23

• SMH26

• SEH31• To be removed (Removal of Continuous Transfer System)*

• Replaced with straight beam pipe

• SMH42• To be replaced by a new septum**

• Difficulties in modeling laminated steel sections

• Measurements presented in +

• SMH57

22

*https://edms.cern.ch/ui/file/1981131/0.1/PS-LJ-EC-0007-00-10.pdf

**https://edms.cern.ch/document/1856808/0.1

+https://indico.cern.ch/event/860185/contributions/3623056/


Comments on Remaining Septums

• SMH16

• SEH23

• SMH26

• SMH57

• Septums contain laminations

which are extremely difficult to

model

• See SMH42+

• 3D Models are not available

23

+https://indico.cern.ch/event/860185/contri

butions/3623056/


To Come: CODD Elements

From: https://indico.cern.ch/event/750790/



Questions?

Comments?


Extra Slides


All KFA13/KFA21 Plots


BFA09: Additional Transition Results


BFA09: Vary Reference File

Vary Magnitude Vary Ref Length

29

Mech Length is 1.175 m


BFA09: Material Definitions

30

Wire DefinitionWake Ferrite Definition


BFA09: Compare Meshes


PS Impedance Model Update: KFA28 & BFA09...IWG#37 Branko K. Popovic 12 13 KFA28 : 3D Model from Paper Drawings IWG#37 Branko K. Popovic KFA28 Longitudinal Impedance 14 Mode at 1.19

Documents