PS Impedance Model

Update: KFA28 & BFA09Branko Popovic

30/01/20

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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

• https://indico.cern.ch/event/750790/contributions/3108016/

• SPS Injection Losses Review

• https://indico.cern.ch/event/672967/contributions/2753563/

• PS-BD-WG #6

• https://indico.cern.ch/event/678530/contributions/2779037/

• PS-BD-WG #1

• https://indico.cern.ch/event/662292/contributions/2704441/

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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.

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

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Elements Covered in this Presentation

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum

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Elements Covered

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum

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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

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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

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Background: Schematic Solver*

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

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Compare with Wakefield (Terminations Shorted)

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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

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Elements Covered

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum

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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

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KFA28 : 3D Model from Paper Drawings

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KFA28 Longitudinal Impedance

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Mode at 1.19 GHz

Mode at 1.51 GHz

Wire Simulation Modes

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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

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Elements Covered

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum

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BFA09: 3D Model from Paper Drawings

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Pedestal Staircase

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8C11 Ferrite 8C11 Ferrite

Simulations in Wire and Wakefield

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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

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Regarding Removing vs Disconnecting Staircase

Component

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

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Elements Covered

• KFA13/21 Resimulation

• KFA28 Simulations

• BFA09 Simulations

• Commentary on Septum

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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

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*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/

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Comments on Remaining Septums

• SMH16

• SEH23

• SMH26

• SMH57

• Septums contain laminations

which are extremely difficult to

model

• See SMH42+

• 3D Models are not available

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

butions/3623056/

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To Come: CODD Elements

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

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Questions?

Comments?

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Extra Slides

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All KFA13/KFA21 Plots

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BFA09: Additional Transition Results

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BFA09: Vary Reference File

Vary Magnitude Vary Ref Length

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Mech Length is 1.175 m

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BFA09: Material Definitions

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Wire DefinitionWake Ferrite Definition

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BFA09: Compare Meshes

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