Electron Cloud Build Electron Cloud Build- Electron Cloud Build - - PowerPoint PPT Presentation

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Electron Cloud Build Electron Cloud Build- Electron Cloud Build - - PowerPoint PPT Presentation

Oct 31, 2022 277 likes •396 views

Electron Cloud Build Electron Cloud Build- Electron Cloud Build Electron Cloud Build -Up Modeling - - Up Modeling Up Modeling- Up Modeling - - Part 1 - Part 1 Part 1 Part 1 Roberto Roberto Cimino Cimino ( (LNF LNF- -INFN) INFN)

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SLIDE 1
  • Electron cloud issues for the APS superconducting undulator -

Katherine Harkay (Argonne National Laboratory)

Electron Cloud Build Electron Cloud Build Electron Cloud Build Electron Cloud Build-

  • Up Modeling

Up Modeling Up Modeling Up Modeling-

  • Part 1

Part 1 Part 1 Part 1 Roberto Roberto Roberto Roberto Cimino Cimino Cimino Cimino ( ( ( (LNF LNF LNF LNF-

  • INFN)

INFN) INFN) INFN) Part 2 will be discussed by Gerry Part 2 will be discussed by Gerry Part 2 will be discussed by Gerry Part 2 will be discussed by Gerry Dugan Dugan Dugan Dugan (Cornell (Cornell (Cornell (Cornell University) University) University) University)

  • R. Cimino
  • Analysis of Synchrotron Radiation using SYNRAD3D and Plans

to Create a Photoemission Model –Laura Boon (Purdue University)

  • Electron Dynamics in the Wigglers of CESR-TA -

Christine Celata (LBNL / Cornell University)

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SLIDE 2
  • Some new and exciting challenges to the community:
  • E-cloud @Electron machines! (K. Harkay)

(are codes adequate for computing e-cloud @Electron accelerators?)

  • Need of better knowledge of input parameters not so necessary in

Proton or positron machine (High energy photoelectrons ; Photo- reflection, more accurate photoemission model (L Boon) )

  • All in a cryogenic System (Heat load problem, and in presence of
  • R. Cimino

physisorbed gas… ..).

  • Need of improved (3D) and more detailed (time consuming)

simulation codes to follow trapped electrons and wiggler dynamics

  • n longher time scale (memory effects… .) (Ch. Celata).

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SLIDE 3

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  • R. Cimino
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  • Electron beam poorly modeled with same parameters (100

Ah additional conditioning, reducing δmax)

  • Avg. impact energy overestimated by factor 10 (150 eV vs.

10 eV msrd)

  • Photoelectron model overly simplified – could not

improve comparison

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SLIDE 4

On high photon energy photoemission: Cross section count!

  • R. Cimino

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SLIDE 5

Photon reflectivity from Al vacuum chamber of DAΦNE

  • N. Mahne, A. Giglia, S. Nannarone and R. Cimino (2004)
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SLIDE 6

Photon reflectivity from Al vacuum chamber of DAΦNE

  • N. Mahne, A. Giglia, S. Nannarone and R. Cimino (2004)
  • R. Cimino

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SLIDE 7

Photon reflectivity from Al vacuum chamber of DAΦNE

  • N. Mahne, A. Giglia, S. Nannarone and R. Cimino (2004)

Very difficult to model (reflectivity from rough surfaces) … .. Maybe easier to measure, once photons (of the right energy) are available.

  • R. Cimino

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BUT We sometime forget that we ARE the community producing SR light!!! Just need to use it!!!

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SLIDE 8

Typically scrubbing experiments are done at RT. Does Typically scrubbing experiments are done at RT. Does Typically scrubbing experiments are done at RT. Does Typically scrubbing experiments are done at RT. Does scrubbing changes at LT? scrubbing changes at LT? scrubbing changes at LT? scrubbing changes at LT? two more questions of relevance to two more questions of relevance to two more questions of relevance to two more questions of relevance to e e e e-

  • cloud analysis in

cloud analysis in cloud analysis in cloud analysis in Superconducting environment. Superconducting environment. Superconducting environment. Superconducting environment.

  • R. Cimino

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Laboratory experiments are done in an “open geometry” Laboratory experiments are done in an “open geometry” Laboratory experiments are done in an “open geometry” Laboratory experiments are done in an “open geometry” while the machine is in a “close geometry”, does it while the machine is in a “close geometry”, does it while the machine is in a “close geometry”, does it while the machine is in a “close geometry”, does it matter? Specially in presence of physisorbed gas, on a matter? Specially in presence of physisorbed gas, on a matter? Specially in presence of physisorbed gas, on a matter? Specially in presence of physisorbed gas, on a pump (the 20 K wall) and without much possibility pump (the 20 K wall) and without much possibility pump (the 20 K wall) and without much possibility pump (the 20 K wall) and without much possibility

  • f removing it?
  • f removing it?
  • f removing it?
  • f removing it?
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SLIDE 9

Scrubing efficiency at 200 eV

0.5 0.6 0.7 0.8 0.9 1.0

First question: good news

1. 1. 1.

  • 1. Does the scrubbing efficiency depends on T?

Does the scrubbing efficiency depends on T? Does the scrubbing efficiency depends on T? Does the scrubbing efficiency depends on T?

  • R. Cimino

9

0.0 0.1 0.2 0.3 0.4 0.5 0.0000 0.0002 0.0004 0.0006 0.0008 0.0010

Dose (C) @ 9K @ RT

Not significantly! In an open geometry! Not significantly! In an open geometry! Not significantly! In an open geometry! Not significantly! In an open geometry!

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SLIDE 10

“open” vs. “close” geometry.

At LT we may be in presence of a thick layer of gas At LT we may be in presence of a thick layer of gas At LT we may be in presence of a thick layer of gas At LT we may be in presence of a thick layer of gas Close geometry(first attempt) => continuous gas dosing! Close geometry(first attempt) => continuous gas dosing! Close geometry(first attempt) => continuous gas dosing! Close geometry(first attempt) => continuous gas dosing!

1.6 1.8 Y Ep=150 eV; Cu @ 9K Clean Surface after 150 Ml CO

2

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scrubbing scrubbing scrubbing scrubbing at at at at LT LT LT LT while while while while dosing dosing dosing dosing seems seems seems seems to to to to change change change change things! things! things! things!

1.0 1.2 1.4 0.002 0.004 SEY Dose (C) Start dosing CO at 2 x 10

  • 8 mbar

2 2 2 2

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SLIDE 11

EC build EC build EC build EC build-

  • up session

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  • II

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  • by

by by by Gerry Gerry Gerry Gerry Dugan Dugan Dugan Dugan (Cornell University) (Cornell University) (Cornell University) (Cornell University)

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