slide1
Download
Skip this Video
Download Presentation
Heat load due to e-cloud in the HL-LHC triplets

Loading in 2 Seconds...

play fullscreen
1 / 68

Heat load due to e-cloud in the HL-LHC triplets - PowerPoint PPT Presentation


  • 164 Views
  • Uploaded on

Heat load due to e-cloud in the HL-LHC triplets. G. Iadarola , G. Rumolo. Many thanks to: H.Bartosik , R. De Maria, R. Tomas, L. Tavian. 19th HiLumi WP2 Task Leader Meeting - 18 October 2013. Outline. Present inner triplets Layout and optics PyECLOUD simulations

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Heat load due to e-cloud in the HL-LHC triplets' - topper


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Heat load due to e-cloud in the HL-LHC triplets

G. Iadarola, G. Rumolo

Many thanks to:

H.Bartosik, R. De Maria, R. Tomas, L. Tavian

19th HiLumi WP2 Task Leader Meeting - 18 October 2013

slide2

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide3

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide4

Machine layout and optics near IP1

3L1

1L1

1R1

3R1

  • IP1

B2L1

A2L1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide5

Machine layout and optics near IP1

  • IP1

1R1

3R1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide6

Machine layout and optics near IP1

  • IP1

1R1

3R1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide7

Machine layout and optics near IP1

  • IP1

1R1

3R1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide8

Machine layout and optics near IP1

  • IP1

1R1

3R1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide9

The longitudinal direction

  • The delay between two following bunch passages changesalong the machine elements
  • Locations of long range encounters spaced by half the bunch spacing
  • IP1

7.5 m

Beam 1

  • 25 ns spac.

Beam 2

slide10

The longitudinal direction

  • The delay between two following bunch passages changesalong the machine elements
  • Locations of long range encounters spaced by half the bunch spacing
  • IP1

7.5 m

Beam 1

  • 25 ns spac.

Beam 2

slide11

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide12

PyECLOUD simulations for the inner triplets

  • Quite a challenging simulation scenario:
  • Two beams with:
    • Different transverse position (off center)
    • Different transverse shape
    • Arbitrarily delayed with respect to each other (no real bunch spacing)
slide13

PyECLOUD simulations for the inner triplets

  • Quite a challenging simulation scenario:
  • Two beams with:
    • Different transverse position (off center)
    • Different transverse shape
    • Arbitrarily delayed with respect to each other (no real bunch spacing)
  • Quadrupolarmagnetic field
  • Non elliptical chamber
slide14

PyECLOUD simulations for the inner triplets

  • Quite a challenging simulation scenario:
  • Two beams with:
    • Different transverse position (off center)
    • Different transverse shape
    • Arbitrarily delayed with respect to each other (no real bunch spacing)
  • Quadrupolarmagnetic field
  • Non elliptical chamber

Required the introduction of new features in PyECLOUD

slide15

PyECLOUD simulations for the inner triplets

  • Quite a challenging simulation scenario:
  • Two beams with:
    • Different transverse position (off center)
    • Different transverse shape
    • Arbitrarily delayed with respect to each other (no real bunch spacing)
  • Quadrupolarmagnetic field
  • Non elliptical chamber

Required the introduction of new features in PyECLOUD

  • Beam properties (delay, position, size) changing along the structure:
  • Simulated 10 slices per magnet
  • SEY = 1.0, 1.1, … , 2.0
  • 50 ns and25 ns
slide16

PyECLOUD simulations for the inner triplets

  • Quite a challenging simulation scenario:
  • Two beams with:
    • Different transverse position (off center)
    • Different transverse shape
    • Arbitrarily delayed with respect to each other (no real bunch spacing)
  • Quadrupolarmagnetic field
  • Non elliptical chamber

Required the introduction of new features in PyECLOUD

  • Beam properties (delay, position, size) changing along the structure:
  • Simulated 10 slices per magnet
  • SEY = 1.0, 1.1, … , 2.0
  • 50 ns and25 ns

~1000 simulations,

~48 h for two bunch trains,

~120 GB of sim. data

slide17

Simulated scenarios

  • 25 ns beam – 1.15 x 1011 ppb

38

72

8

72

8

72

8

72

38

72

8

72

8

72

8

72

  • 50 ns beam – 1.65 x 1011 ppb

36

4

36

4

36

4

36

19

36

4

36

4

36

4

36

19

  • Other beam parameters:
  • Beam energy: 4 TeV
  • Transverse emittance: 2.4 μm
  • Bunch length: 1.3 ns
  • Optics withβ* = 0.6 m
slide18

A look to the EC buildup

  • Few snapshots of the electron distribution (50 ns spacing)

Beam 1

slide19

A look to the EC buildup

  • The presence of two beams enhances the multipacting efficiency, especially far enough from the locations of the long range encounters
slide20

A look to the EC buildup

  • The presence of two beams enhances the multipacting efficiency, especially far enough from the locations of the long range encounters
slide21

Heat load density along the triplet - 50 ns

1R1

A2R1

B2R1

3R1

  • Locations of long range encounters
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide22

Heat load density along the triplet - 50 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide23

Heat load density along the triplet - 50 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide24

Heat load density along the triplet - 50 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide25

Heat load density along the triplet - 50 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide26

Heat load density along the triplet - 25 ns

1R1

A2R1

B2R1

3R1

  • Locations of long range encounters
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide27

Heat load density along the triplet - 25 ns

1R1

A2R1

B2R1

3R1

  • As in the other quardupoles in the LHC, the multipacting threshold is already quite low even for a single beam with 25 ns spacing
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide28

Heat load density along the triplet - 25 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide29

Heat load density along the triplet - 25 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide30

Heat load density along the triplet - 25 ns

1R1

A2R1

B2R1

3R1

  • The presence of the two beams leads to an important lowering of the multipacting threshold w.r.t. the single beam case (dashed)
  • Remarks:
  • EC much weaker close to long range encounters
  • Modules with the same beam screen behave very similarly
slide31

Average heat load density – 50 ns vs. 25 ns

  • For each triplet we get:
  • Remarks:
    • Above threshold values are very similar  enhancement from hybrid spacings much stronger on the 50 ns than on 25 ns
slide32

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide33

Machine observations – 50 ns

Data provided by L. Tavian

  • No big change during ramp and squeeze
slide34

Machine observations – 50 ns

  • No big change during ramp and squeeze
slide35

Machine observations – 50 ns

Data provided by L. Tavian

  • Heat load much higher than in two-aperture quadrupoles
slide36

Machine observations – 25 ns (4 TeV)

Data provided by L. Tavian

  • No big change during ramp and squeeze
slide37

Machine observations – 25 ns (4 TeV)

  • No big change during ramp and squeeze
slide38

Machine observations – 25 ns (4 TeV)

Data provided by L. Tavian

  • Heat load similar to two-aperture quadrupoles
slide39

Comparison against simulations

25 ns, 450 GeV

50 ns, 4 TeV

Fill 3405

Fill 3286

25 ns, 4 TeV

  • 1.2 < SEYmax < 1.3
  • is compatible with the observations

Fill 3429

slide40

Crosscheck with single beam MDs

  • For the estimated SEY value we do not expect nor observe EC in the triplets with only one beam with 50 ns spacing circulating in the LHC
slide41

Crosscheck with single beam MDs

  • For the estimated SEY value we do not expect nor observe EC in the triplets with only one beam with 50 ns spacing circulating in the LHC
slide42

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide43

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide44

Optics, layout and apertures

D1

Q1

Q3

Q2 (A/B)

For the moment, only quadrupoles have been simulated

  • Thanks to R. De Maria

Q1 (A/B)

Q3 (A/B)

D1

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide45

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide46

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide47

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide48

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide49

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide50

Optics, layout and apertures

Present

D1

Q1

Q3

Q2 (A/B)

  • IP1, 4 TeV, β* = 0.6 m

Q1 (A/B)

Q3 (A/B)

D1

HiLumi

Q2 (A/B)

  • IP1, 7 TeV, β* = 0.15 m
slide51

Outline

  • Present inner triplets
    • Layout and optics
    • PyECLOUD simulations
    • Heat load measurements and estimate of the SEY
  • Inner triplets for the HL-LHC upgrade
    • Layout and optics
    • Heat load estimates from PyECLOUD simulations
slide52

Simulated scenario

  • 25 ns beam – 2.20 x 1011 ppb

38

72

8

72

8

72

8

72

38

72

8

72

8

72

8

72

  • Other beam parameters:
  • Beam energy: 7TeV
  • Transverse emittance: 2.5 μm
  • Bunch length: 1.0 ns
  • Optics withβ* = 0.15 m
slide53

A look to the EC buildup – HiLumi triplets

  • Few snapshots of the electron distribution  much wider stripes for HiLumi triplets

HiLumi

Present

slide54

Heat load along the triplet

Present triplets

  • Locations of long range encounters

HiLumitriplets

slide55

Heat loads

  • Bunch intensity is larger but also chamber is wider
  •  energy of multipacting electrons is quite similar

Present triplets

HiLumi triplets

slide56

Heat loads

  • Bunch intensity is larger but also chamber is wider
  •  energy of multipacting electrons is quite similar
  •  number of impacting electrons about x2 larger

Present triplets

HiLumi triplets

slide57

Heat loads

  • Bunch intensity is larger but also chamber is wider
  •  energy of multipacting electrons is quite similar
  •  number of impacting electrons about x2 larger
  •  Total heat load about x2 larger

Present triplets

HiLumi triplets

  • SEYmax in the present triplets at the end of 2012
  • D1 and correctors not included!
slide58

Summary and conclusions

  • Simulations show a strong enhancement of the EC due to the presence of the two beams  extremely low multipacting thresholds (SEYth<1.1 for 25 ns beams)
  • Comparing measured heat load against simulation we infer SEYmax = ~1.3 for the present triplets (crosschecked in different beam conditions )
  • Simulations for the HiLumi scenario show x2 stronger heat load w.r.t. the present scenario (SEYmax = ~1.3  HL = ~500 W – D1 and correctors to be added)
  • Heat load could be strongly reduced by EC mitigation strategies:
    • Low SEY coating (but we need SEYmax<1.1 to have full suppression)
    • Clearing electrode (EC localized in a region where there should be enough aperture to place a polarized plate/wire)
slide60

Machine layout and optics near IP1 - present

  • Common beam pipe
  • Separated beam pipes
  • Separated beam pipes
  • IP1
  • IP1, 4 TeV, β* = 0.6 m
slide61

Machine layout and optics near IP1 - HiLumi

  • Common beam pipe
  • Separated beam pipes
  • Separated beam pipes
  • IP1
  • IP1, 4 TeV, β* = 0.6 m
slide62

Machine layout and optics near IP1 - present

3L1

1L1

1R1

3R1

  • IP1

B2L1

A2L1

A2R1

B2R1

  • IP1, 4 TeV, β* = 0.6 m
slide63

Machine layout and optics near IP1 - HiLumi

3L1

1L1

1R1 (A/B)

3R1 (A/B)

  • IP1

2R1 (A/B)

B2L1

A2L1

  • IP1, 4 TeV, β* = 0.6 m
slide64

The longitudinal direction

  • The delay between two following bunch passages changesalong the machine elements
  • Locations of long range encounters spaced by half the bunch spacing
  • IP1

15 m

Beam 1

  • 50 ns spac.

Beam 2

slide65

Average heat load density – 50 ns vs. 25 ns

  • Remarks:
    • Above threshold values are very similar  enhancement from hybrid spacings much stronger on the 50 ns than on 25 ns
slide66

A look to the EC buildup – HiLumi triplets

  • Few snapshots of the electron distribution  much wider stripes
slide67

A look to the EC buildup – present triplets

  • Few snapshots of the electron distribution

Beam 1

slide68

A look to the EC buildup – HiLumi triplets

  • Few snapshots of the electron distribution  much wider stripes
ad