VELO SMOG2 Heat Load Localization Analysis

1. VELO SMOG2 Heat Load Localization Analysis B. Popovic 5/03/2019

2. Past VELO Presentations • Wire Measurements of VELO Mockup • Benchmarking of VELO Simulation Model with the Mockup Measurements • Wire Measurements and Simulations Presented • https://indico.cern.ch/event/698038/contributions/3124154/ • Simulations and Measurements of VELO Mockup • Wire Measurements and Simulations Presented • Complete VELO Simulation results • https://indico.cern.ch/event/764129/contributions/3171803/ • VELO/SMOG2 Simulations • Simulations of the Complete VELO with SMOG 2 Device • Wire, Eigenmode and Wake Simulations • https://indico.cern.ch/event/765714/contributions/3178576/ • Preliminary Work on VELO Heating Simulations • Method and Early Simulation Results • https://indico.cern.ch/event/797962/contributions/3316163/ • Impedance Effects on SMOG2 • Presentation to PBC-FT (Gas Targets) • https://indico.cern.ch/event/797685/contributions/3314381/

3. Overview • CST Eigenmode simulations of the VELO with the SMOG2 in the open position • ~200 Modes • Manually doing convergences • HL-LHC Beam Spectrum • Calculating the total power deposited into each mode one by one • Use the total power deposited number and eigenmode simulation results to determine the power deposited on the specific elements of the VELO with SMOG2 • Mode by Mode (power in single mode) • Two different outputs • Individual mode power of individually frequency shifted modes • Total power of uniformly frequency shifted modes • Two beams question?

4. SMOG2 Model FROM SMOG2 PROPOSAL:IWG # 22 Closed Open • https://indico.cern.ch/event/751383/

5. Complete VELO model with SMOG2 (OPEN Position)

6. Why Only Simulating in the Open Position? • In the closed position, the gap is small thus little coupling to outer tank (resonance modes) • Impedance is broadband Impedance of Open Position Impedance of Closed Position • From: https://indico.cern.ch/event/765714/contributions/3178576/

7. Beam Definition Using BLonD RF Tool Box Beam File Input: Bunch parameters: Binomial exponent: 2.5 Bunch length [ns]: 1.2 Intensity per bunch [1e10 ppb]: 23 Line density: binomial Filling scheme: Buckets between batches: 80 Buckets between bunches: 10 Buckets between fills: 320 Number of batches: 1 Number of bunches: 2748 Number of fills: 1 General parameters: Circumference [m]: 26658.86 Momentum [1e9 eV/c]: 7000 Particle type: proton Transition gamma: 53.83 RF parameters: Harmonic numbers: - 35640 RF voltages: - 10000000 RF phases: - 0

8. Two Different Outputs *Fixed a typo where I wrote 1 KHz instead of 100 KHz • Mode by Mode (power in single mode) • Allow for worst case scenario frequency shift of +/-20MHz • Forces each mode to individually hit a bunch spacing harmonic • Each mode has it’s own frequency offset • Returns power into mode and freq. offset to hit bunch spacing harmonic • Total power (sum of all modes’ powers) • Freq. shift of the ~200 modes in unison • 100 KHz steps within a frequency window of +/-20MHz • 0 MHz point is the total power from the original Eigendata

9. Beam Spectrum: With individually shifted modes Extremely Pessimistic Freq. Shifts Thanks to the BLonD Team (BE-RF-BR) for the beam spectrum code

10. Total Power into the VELO with SMOG2 (Mode by Mode): Allowing a Resonance Mode Shift of +/-20 MHz Frequency shift of -4.44 MHz Frequency shift of -6.12 MHz Each point is one mode

11. Sensitivity Analysis of Frequency Offset: Total Power of all modes with uniform freq. offset • Each point is the summed losses of all the modes • 100 KHz Steps With no freq. offset (directly from Eigenmode results) → Negligible Heating (13.73 W TOTAL) Each is the losses of one mode

12. VELO: Mode by Mode Losses VELO

13. VELO • Each point is the summed losses of all the modes • 100 KHz Steps

14. Aluminum SMOG CELL: Mode by Mode Losses Frequency shift of 6.12 MHz (13W) Aluminum SMOG Cell Frequency shift of -4.6 MHz (9.5 W)

15. Aluminum SMOG CELL • Each point is the summed losses of all the modes • 100 KHz Steps

16. Copper WFS: Mode by Mode Losses Copper WFS Frequency shift of 6.12 MHz Frequency shift of 4.44 MHz

17. Copper WFS • Each point is the summed losses of all the modes • 100 KHz Steps

18. Enclosure (Vacuum Tank): Mode by Mode Losses Enclosure is surrounding stainless steel tank (boundary conditions)

19. Enclosure(Vacuum Tank) • Each point is the summed losses of all the modes • 100 KHz Steps

20. Two Beams Question: Is this too pessimistic? Doubling of the beam intensity to represent two beams → 4x the heating • Each point is the summed losses of all the modes • 100 KHz Steps Frequency shift of 4.44 MHz Frequency shift of 6.12 MHz

21. Aluminum SMOG CELL Doubling of the beam intensity to represent two beams → 4x the heating

22. Summary • *Note that this is 100 kHz steps • Eigenmode Simulations of 200 modes • HL-LHC Beam Spectrum • Allow for an extremely pessimistic resonance shifts of +/- 20 MHz • Forces each mode to hit a bunch spacing harmonic • Heating is dominated by certain modes, not sum of modes • Sensitivity scanned shows this • Maximum Heating of SMOG cell by a single mode (worst case scenario) • 14 Watts (6.12 MHz offset) => x4 for two beams ? • Maximum Heating of SMOG cell by the sum of the modes • 9.5 Watts (6.1 MHz * offset) => x4 for two beams ?

23. Summary • *Note that this is 100 kHz steps • Eigenmode Simulations of 200 modes • HL-LHC Beam Spectrum • Two different methods to analyze heating in the VELO • Power in individual mode (Force each mode to hit a bunch spacing harmonic) • SMOG Cell: Single mode with 14 Watts (6.12 MHz offset) → x4 for two beams ? • Total power from sum of the modes (sweep all modes in unision) • SMOG Cell: 9.5 Watts (6.1 MHz * offset) →x4 for two beams ? • Heating is dominated by certain modes, not sum of modes

24. Questions?

25. Total Losses: No frequency shift (taking eigenmodesdirectly) -------- Total Losses -------- Al_SMOG_CELL : 0.04631 W Al_VELO : 0.1882 W Copper_SMOG_WFS : 0.0237 W Copper_WFS : 0.02566 W Enclosure : 7.547 W PEC : 0.0 W Stainless : 0.1155 W Stainless_Tables : 5.779 W Total : 13.73 W ------------------------------ • Each point is the summed losses of all the modes • 100 KHz Steps With no freq. offset (directly from Eigenmode results) → Negligible Heating (13.73 W Total)

26. Supplementary Slides: Other Elements in the VELO

27. Stainless: Mode by Mode Losses Stainless

28. Stainless • Each point is the summed losses of all the modes • 100 KHz Steps

29. SMOG WFS: Mode by Mode Losses SMOG WFS

30. SMOG WFS • Each point is the summed losses of all the modes • 100 KHz Steps

31. Stainless Steel Tables:Modeby Mode Losses Stainless Tables

32. Stainless Tables • Each point is the summed losses of all the modes • 100 KHz Steps