ECLOUD Clearing Electrode and Detector

X. Zhang, A. Chen, R. Stewart

Effects of Clearing Electrode

Preliminary Design

Kapton InsulationS.S. strip w. or w/o NEG coating

Clearing Electrode • Pros:

Can suppress Ecloud efficiently;Easy to install in magnets than the coating;No beam scrubing time needed;Can be used as to improve vacuum (like Tevatron

SNEG);Can measure Ecloud density in magnets;Cross check with microwave measurements;

• Cons:Impedance ?Longevities?

Electron Distributions

11/11/2009 Yulin Li AVS 56th International Symposium, San Jose, CA 6

RFA – Grids and Collectors

RFA Retarding Grids: Electroformed copper mesh (71 LPI, 15m WW, 13m THK) bonded to SST frames. T > 90%. 0.3 m gold ‘flashing’ to reduce SEY on the meshes

RFA Electron Collectors: Printed flexible circuits, Cu-clad Kapton ribbons, UHV compatible, ~13m thick

CesrTA RFAs in Magnets

11/11/2009 Yulin Li AVS 56th International Symposium, San Jose, CA 7

SC Wiggler RFA Structures

• Unique design allowing RFA structures fit within 2.5 mm space

• Significant efforts in design and tests to ensure survivability of the flexible circuit collector through welding steps

• Lack of vacuum pumping and silicon contamination are issues to be addressed

Grids nested in ceramic frames

Collector pinned in

CesrTA RFAs in Magnets