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– Indication that the simulations are relevant (very important for a

complicated geometry such as the TCTP)

PhD thesis of Hugo Day (2013)

Ferrite considered was 8C11 at the time

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

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.

Simulations of longitudinal impedance

Frequency in GHz

Frequency in GHz

Long

itudi

nal I

mpe

danc

e in

Ohm

Long

itudi

nal I

mpe

danc

e in

Ohm

1 mm

10 mm

Half gap= 1mm

Half gap= 10mm

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

Superposition of beam spectrum with impedance (50 ns beam)

Pow

er c

ontr

ibuti

on in

WFrequency in Hz

Main contribution from the broad peaks around 500 MHz, peaks beyond 1 GHz only significant for the Gaussian distribution

Superposition of beam spectrum with impedance (25 ns beam)

Pow

er c

ontr

ibuti

on in

W

Frequency in Hz

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

Power loss (post-LS1, 25 ns, bunch length = 9 cm)

50% to 100% of this heat load goes to the two lines of ferrite

Power loss vs gap (post-LS1, 50 ns)

50% to 100% of this heat load goes to the two lines of ferrite

Power loss vs gap (HL-LHC, 50 ns)

50% to 100% of this heat load goes to the two lines of ferrite

Power loss vs gap (HL-LHC, 25 ns)

50% to 100% of this heat load goes to the two lines of ferrite

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