LHC e- cloud simulations

C.Octavio Domínguez, Giovanni Rumolo, Frank Zimmermann

17th January2011 - e- cloud simulations

2

Contents

1) LHC IR3:

I. State of the art

2) LHC arc dipoles:

II. Emittance scan (onset, build up & energy distribution)

III. Intensity scan (build up & x-flux distribution)

17th January2011 - e- cloud simulations

3

Contents

1) LHC IR3:

I. State of the art

2) LHC arc dipoles:

II. Emittance scan (onset, build up & energy distribution)

III. Intensity scan (build up & x-flux distribution)

17th January2011 - e- cloud simulations

417th January2011 - e- cloud simulations

LHC IR3

First idea Try to reproduce this plot, BUT 4 parameters: P, SEY, emax and R

517th January2011 - e- cloud simulations

LHC IR3 – 8.85 ms

~ Factor 6

~ Factor 3

Memory effect

617th January2011 - e- cloud simulations

LHC IR3 – 8.85 ms

~ Factor 1.1

~ Factor 1.1

No memory effect ??

717th January2011 - e- cloud simulations

LHC IR3

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LHC IR3 – Energy distribution

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LHC IR3 – Energy distribution

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LHC IR3 – Work to do

Look at 28.85 and 38.85 ms

Look at the flux (maybe related to the pressure rise)

Make the study for individual batches of 12, 24 and 36 bunches

…

11

Contents

1) LHC IR3:

I. State of the art

2) LHC arc dipoles:

II. Emittance scan (onset, build up & energy distribution)

III. Intensity scan (build up & x-flux distribution)

17th January2011 - e- cloud simulations

12

LHC arc dipoles - e scan

17th January2011 - e- cloud simulations

Geometry:

Parameters:

Nb = 1.1 · 1011 ppb; B = 0.535 T (dipolar field) ; sz = 0.118 m

emax = 230 eV ; R = 0.7; P=1nTorr

Filling scheme: 1 batch (36 bunches)

22 mm

18 mm

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LHC arc dipoles - e scan

eN (mm) SEY (onset/significative density)

1 1.9 / 2.3 (~0.5 1011) - 2.4 (~3 1011)

2 1.9 / 2.3 (~0.45 1011) - 2.4 (~3 1011)

3 1.9 / 2.4 (~ 1011)

4 2.0 / 2.4 (~ 1011)

10 2.0 / 2.4 (~ 1011)

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LHC arc dipoles - e scan Build up

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LHC arc dipoles - e scan Build up

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LHC arc dipoles - e scan Build up

1717th January2011 - e- cloud simulations

LHC arc dipoles - e scanEnergy distribution

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LHC arc dipoles - e scanEnergy distribution

1917th January2011 - e- cloud simulations

LHC arc dipoles - e scanEnergy distribution

2017th January2011 - e- cloud simulations

LHC arc dipoles - e scanEnergy distribution

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Contents

1) LHC IR3:

I. State of the art

2) LHC arc dipoles:

II. Emittance scan (onset, build up & energy distribution)

III. Intensity scan (build up & x-flux distribution)

17th January2011 - e- cloud simulations

22

LHC arc dipoles - Nb scan

17th January2011 - e- cloud simulations

Geometry:

Parameters:

eN = 2.3 mm; B = 0.535 T (dipolar field) ; sz = 0.118 m

emax = 230 eV ; R = 0.7; P=1nTorr

SEY=2.5 (above multipacting onset)

Filling scheme: 1 batch (36 bunches)

22 mm

18 mm

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LHC arc dipoles - Nb scanBuild up

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LHC arc dipoles - Nb scanBuild up

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LHC arc dipoles - Nb scanx flux distribution

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LHC arc dipoles - Nb scanx flux distribution

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LHC arc dipoles - Nb scanx flux distribution

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