NLC Beam Delivery

1. NLC Beam Delivery Area Engineering: Vacuum System Cost Model Presentation by Leif Eriksson, 02/09/99

2. NLC Beam Delivery, Vacuum: General • The NLC Beam Delivery systems begins where the NLC Linac ends. • It consists of: • Collimation section • Beam Delivery 1 and 2: • IP Switch • Big Bend: • e+ • e- • Final Focus • e+ • e- • IR 1 and 2 Leif Eriksson, Area Engineer

3. NLC Beam Delivery, Vacuum: Tunnel Layout • A straw man figure of tunnel access: Leif Eriksson, Area Engineer

4. Must have: Base Pressure 5E-8 Torr Low electrical resistance Small aperture, ~ 1/2” OD Uniform inner diameter, tapered Specials: Big Bend, absorb synchrotron radiation NLC Beam Delivery, Vacuum: Baseline specs Leif Eriksson, Area Engineer

5. NLC Beam Delivery Vacuum: Materials • Materials to chose from: • Stainless steel, low outgassing, cheap • Aluminum, low outgassing, cheap, good conductor, easy to extrude • Copper, low outgassing, good heat absorber, good conductor, easy to extrude Leif Eriksson, Area Engineer

6. NLC Beam Delivery, Vacuum: Comparison • Stainless steel is less favored choice because of high electrical resistance • It’s a toss up between aluminum and copper Leif Eriksson, Area Engineer

7. NLC Beam Delivery, Vacuum: The numbers Leif Eriksson, Area Engineer

8. With an aluminum chamber the pump spacing is 1-3 m With a copper chamber the pump spacing is 13-18 m Big Bend may need an anti-chamber to absorb synchrotron radiation Copper is the preferred material from an engineering stand point: less component-better reliability Low outgassing Good thermal properties Lends itself well for extrusion and brazing Easy to machine NLC Beam Delivery, Vacuum: Conclusion Leif Eriksson, Area Engineer

9. NLC Beam Delivery, Vacuum: Components - 1 • NLC Beam Delivery vacuum specification for the purpose of cost estimation and WBS • GENERAL • The NLC Beam Delivery vacuum system is an Ultra High Vacuum system. All components in direct contact with the NLC Beam Delivery vacuum system must comply with “Technical Specifications for Vacuum Systems”, SLAC-TN-86-6. • BASE PRESSURE • - The highest pressure in the NLC Beam Delivery System must not exceed 5E-8 Torr. • PUMPS • - The NLC Beam Delivery vacuum system is ion pumped, the pump size is 30 l/s. • - The ion pumps are of VARIAN type with a removable, gold plated high voltage feed through. Leif Eriksson, Area Engineer

10. NLC Beam Delivery, Vacuum: Components - 2 • PUMPS, cont. • - The pumps should have remote high voltage power supplies accessible during operation. • - The high voltage ion pump power supplies should display error codes into a central control system. • - The spacing of the ion pumps is one ion pump every 10m or 15m depending on beam line aperture. • - The ion pumps are located immediately adjacent and perpendicular to the beam line • - The ion pumps are connected to the beam line through a flange connection. • - Each ion pump has its own mechanical support. • BEAM LINE • - The preferred material for the beam line is copper due to its low out gassing rate, its low electrical resistance and its good thermal properties. • - Flange connections are made by ConFlat type vacuum flanges. • - All vacuum seals in areas in direct contact with the beam must be all-metal. • - Flange connections will be used in component dense areas. • - Where the component density is low the beam line sections will be welded/brazed together in situ. Leif Eriksson, Area Engineer

11. NLC Beam Delivery, Vacuum: Components - 3 • GAUGES • - One gauge assembly measuring total pressure from atmospheric pressure to 2E-10 Torr, every 250m. The gauges must be radiation hardened. • - All functions of the gauge(s) should be able to operate remotely. • - Every beam line section must have a gauge combination, as described above, on both sides of a beam line isolation valve. • RGA • - Every 250m section should contain two Residual Gas Analyzers of radiation hardened type. • - All functions of the RGA should be able to operate remotely. • VALVES • - The beam line isolation valves are all-metal valves of VAT type, radiation hardened. • - The bore is no larger than 1.50”. • - The actuator should be mounted on an extender. Leif Eriksson, Area Engineer

12. NLC Beam Delivery, Vacuum: Components - 4 • VALVES, cont. • - The valves must have mechanical indicators displaying OPEN and CLOSED. • - The valve must have micro switches indication OPEN and CLOSED. • - The valves must be operated by a remote solenoid package, J-box, of SLAC type. • - The valves should have local controls every 500m. • - The valves are located 250 m apart. • - All metal right angle valves, 2 3/4“ CFF should be provided every 50m. • TUNNEL ACCESS • - Access to the tunnel will be provided every 500m. • - A power supply/Control vault will be provided adjacent to the tunnel access, on the ground level. No cable length from a beam line vacuum device to the power supply/ controls vault should have to be longer than 300m. • VACUUM CONTROL ROOM • - The NLC Beam Delivery System should have a centrally located vacuum control room. Leif Eriksson, Area Engineer

13. NLC Beam Delivery, Vacuum: Components - 5 • SUMMARY • Based on the above assumptions the NLC Beam Delivery Vacuum System contains the following components, (one side, two IP’s): • 30 l/s ion pumps 629 EA • Vacuum gauges 33 EA • RGA’s 33 EA • Isolation valves 31 EA • Right angle valves 152 EA • Beam line length 5305 m Leif Eriksson, Area Engineer

14. NLC Beam Delivery, Vacuum: Reference text • All of the presented material is available for downloading from: • http://www-sldnt.slac.stanford.edu/nlc/beamdeliveryhome.htm • See under: • Issues\Engineering • A beam line schematic is also available at this location Leif Eriksson, Area Engineer