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

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) Roberto Roberto Cimino Cimino ( ( LNF LNF - - 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 (Cornell Dugan (Cornell (Cornell (Cornell University) University) University) University) • Electron cloud issues for the APS superconducting undulator - Katherine Harkay (Argonne National Laboratory) • 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) Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10- -11 - - 11 11 11- - - -2010 2010 2010 2010 R. Cimino

• 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 physisorbed gas… ..). -Need of improved (3D) and more detailed (time consuming) simulation codes to follow trapped electrons and wiggler dynamics on longher time scale (memory effects… .) (Ch. Celata). Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 - -11 - 11 11 11- - - -2010 2010 2010 2010 R. Cimino

���������������������� � � ����� � ���������� �������������������������������� ������� ������������������������� �������������������������������������������� !"�����#"��������$%� �������������� ��� &$' (������������' ���������������� ������������������� • ��������������������������)����������� • Electron beam poorly modeled with same parameters (100 ������������������)��������������������� Ah additional conditioning, reducing δ max ) �������*�����������������������+���������� • Avg. impact energy overestimated by factor 10 (150 eV vs. ������� ������������$ 10 eV msrd) • �*�%������������������+���������������� #""�,$ • Photoelectron model overly simplified – could not • -��)����������������������������������� improve comparison .%�/��)�+ (�0123#"�������������������������1���4�#!��!"#" R. Cimino

On high photon energy photoemission: Cross section count! Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10- - -11 - 11- 11 11 - - -2010 2010 2010 2010 R. Cimino

Photon reflectivity from Al vacuum chamber of DA Φ NE N. Mahne, A. Giglia, S. Nannarone and R. Cimino (2004) Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 -11 - - 11 11 11- - - -2010 2010 2010 2010 R. Cimino

Photon reflectivity from Al vacuum chamber of DA Φ NE N. Mahne, A. Giglia, S. Nannarone and R. Cimino (2004) Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 -11 - - 11 11 11- - - -2010 2010 2010 2010 R. Cimino

Photon reflectivity from Al vacuum chamber of DA Φ NE 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. BUT We sometime forget that we ARE the community producing SR light!!! Just need to use it!!! Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 - -11 - 11- 11 11 - - -2010 2010 2010 2010 R. Cimino

two more questions of relevance to two more questions of relevance to two more questions of relevance to e two more questions of relevance to e- e e - -cloud analysis in - cloud analysis in cloud analysis in cloud analysis in Superconducting environment. Superconducting environment. Superconducting environment. Superconducting environment. 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? 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 of removing it? of removing it? of removing it? of removing it? Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10- -11 - - 11 11 11- - - -2010 2010 2010 2010 R. Cimino

First question: good news 1. 1. Does the scrubbing efficiency depends on T? 1. 1. Does the scrubbing efficiency depends on T? Does the scrubbing efficiency depends on T? Does the scrubbing efficiency depends on T? 1.0 Scrubing efficiency at 200 eV 0.9 0.8 0.7 0.6 0.5 0.5 0.4 0.3 @ RT 0.2 0.1 @ 9K 0.0 0.0000 0.0002 0.0004 0.0006 0.0008 0.0010 Dose (C) Not significantly! In an open geometry! Not significantly! In an open geometry! Not significantly! In an open geometry! Not significantly! In an open geometry! Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 - -11 - 11 11 11- - - -2010 2010 2010 2010 R. Cimino 9

“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! Ep=150 eV; Cu @ 9K 1.8 Clean Surface after 150 Ml CO 2 1.6 SEY Y 1.4 Start dosing CO 1.2 2 2 2 2 -8 mbar at 2 x 10 1.0 0 0.002 0.004 Dose (C) scrubbing scrubbing at scrubbing scrubbing at LT at at LT LT LT while while while dosing while dosing seems dosing dosing seems seems to seems to to to change change things! change change things! things! things! Ecloud10 @Cornell 10 Ecloud10 @Cornell 10 Ecloud10 @Cornell 10- Ecloud10 @Cornell 10 -11 - - 11- 11 11 -2010 - - 2010 2010 2010 R. Cimino 10