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Jefferson Lab’s CEBAF (Continuous Electron Beam Accelerator Facility) Vacuum System Overview, Concerns and Diagnostic Tools. Tim Whitlatch OLAV Workshop 2005 - CERN.
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Jefferson Lab’s CEBAF (Continuous Electron Beam Accelerator Facility) Vacuum System Overview, Concerns and Diagnostic Tools Tim WhitlatchOLAV Workshop 2005 - CERN
A user facility for scientists worldwide, its primary mission is to conduct basic research of the atom’s nucleus at the quark level. Uses Superconducting Radio Frequency (SRF) technology for accelerating the electron beam What is CEBAF?
Continuous Electron Beam Accelerator Facility East Arc South LINAC NorthLINAC Injector West Arc Experimental Halls
LINACs 1.0E-10 – 1.0E-9 Torr (As measured in warm girder adjacent to cold cavities) Arcs and Transport 1.0E-7 Torr Insulating Vacuum 1.0E-6 Torr Waveguide Vacuum 5.0 E-10 – 1.0E-8 Torr Vacuum Operating Range
Over 5 km of Beam Line under vacuum (450+) 11/20 l/s Ion Pumps (PE-Gamma) (80+) 35/40 l/s Ion Pumps (PE-Gamma) (45+) Convectron Gages (Granville) (40+) Pirani Gages (HPS) (40+) Cold Cathode Gages (Troy-Onics) (40+) TC gauges (DV6)(Teledyne Hastings) (160+) Valves (3.8 cm) (VAT) (10+) Fast Valves (VAT) (10+) Turbo pump stations (insulating and waveguide vacuum) (8) Differential Pump Stations (NEGs and Ion Pumps) Quantities of Vacuum Equipment
Fast Shut Down System (FSD) (To interrupt the beam) DP Stations ( to protect SRF cavities) Ion Pumps (SRF Cavity protection force valves to close at set point) Pirani Gages For SRF Region 100 to 10-4 Torr (will not allow Ion pumps to turn) Convectron Gages for NON SRF Regions Atm down to 10-3 Torr (valves close at min detectable range) Millisec response time Fast Valves to Protect Superconducting Cavities (<10 msec closing time) UHV valves (.4 second closing time) Vacuum Protection
MEDM (Bar charts with color changes) Archive Viewer (XARR) Strip Tool Diagnostic and Monitoring Tools (Non Invasive)
Protection of SRF Cavity Vacuum and Performance Insulating Vacuum – minimize Cryogenic load Additional Pumping Superfluid Helium leaks into beam line Cryocycles to remove He Age of Components (10 – 15 yrs) Ion Pumps Cold Cathode Gages Radiation Damage Viton seals (leaky Valves) Electronics Beam Strikes Special Considerations/Concerns