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Update on TCTP heating

Update on TCTP heating. H. Day, B. Salvant Acknowledgments: L. Gentini and the EN-MME team. Context. Presentation at the collimation working group in March 2012 Long-standing action for the impedance team, needed to wait for: the eigenmode solver with dispersive material

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Update on TCTP heating

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  1. Update on TCTP heating H. Day, B. Salvant Acknowledgments: L. Gentini and the EN-MME team

  2. Context • Presentation at the collimation working group in March 2012 • Long-standing action for the impedance team, needed to wait for: • the eigenmode solver with dispersive material • Indication that the simulations are relevant (very important for a complicated geometry such as the TCTP)

  3. PhD thesis of Hugo Day (2013) Ferrite considered was 8C11 at the time

  4. Simulations of longitudinal impedance • Very heavy simplifications from the initial CATIA file from Luca Gentini • In particular, RF fingers at entry and exit needed to be replaced by a sheet, and was anyway badly meshed. • Angle of the RF fingers adapted to the jaw position in order to keep contact, however can be different for the real collimator • 1.7 M mesh cells • All materials perfect conductors, except the ferrite, in order to get rid of the resistive wall losses from the jaw • Of course, there is uncertainty on ferrite parameters Half gap scanned between 1mm and 10 mm

  5. Additional assumptions • Impedance which will heat the ferrite should be broadband • Need to suppress the losses from the resistive wall  use perfect conductor everywhere except for ferrite and assume that superposition is possible.

  6. Simulations of longitudinal impedance Half gap= 10mm Half gap= 1mm Longitudinal Impedance in Ohm 10 mm Frequency in GHz • Opening the gap leads to an increase of the amplitude of broad modes • More heating to ferrrite with gap open • Of course, this is not true for resistive wall heating to the jaws Longitudinal Impedance in Ohm 1 mm Frequency in GHz

  7. Superposition of beam spectrum with impedance (50 ns beam) Power contribution in W Frequency in Hz  Main contribution from the broad peaks around 500 MHz, peaks beyond 1 GHz only significant for the Gaussian distribution

  8. Superposition of beam spectrum with impedance (25 ns beam) Power contribution in W Frequency in Hz

  9. Power loss (post-LS1, 25 ns, bunch length = 7.5 cm)  50% to 100% of this heat load goes to the two lines of ferrite

  10. Power loss (post-LS1, 25 ns, bunch length = 9cm)  50% to 100% of this heat load goes to the two lines of ferrite

  11. Power loss vs gap (post-LS1, 50 ns)  50% to 100% of this heat load goes to the two lines of ferrite

  12. Power loss vs gap (HL-LHC, 50 ns)  50% to 100% of this heat load goes to the two lines of ferrite

  13. Power loss vs gap (HL-LHC, 25 ns)  50% to 100% of this heat load goes to the two lines of ferrite

  14. Summary • Heat load to the ferrite can reach of the order of 5 W per side • Opening the gap increases the heat load • After LS1, with standard bunch length of 9 cm, we expect on the order of 1 W in the ferrite per side

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