National Ignition Facility Vacuum Systems Presentation to OLAV Workshop, ORNL July 11-14, 2011 NIF Vacuum Subsystems Managers Igor Maslennikov* John Hitchcock William Collins Farhad Fereydouni *LLNL Contact Ph

NIF Overview IM RELEASE NUMBER: LLNL-PRES

Vacuum is Required Every Time Laser Beam is Focused (or Energy Density is Significantly Increased) IM RELEASE NUMBER: LLNL-PRES vacuum

NIF Vacuum Systems Highlights Stainless steel and Aluminum chambers with elastomer (viton) o-rings Large volumes required to be pumped down to high vacuum (10 -6 Torr range) Large surface area (and therefore outgassing) due to numerous cables and other utilities required for target positioners and diagnostics Highest peak in RGA scan is N 2 (due to use of non-high vacuum compatible materials and air leaks) Using centralized type vacuum systems, where one pump is shared by multiple users High precision (expensive) optics requires usage of dry roughing pumps Roughing pumps with low overall leak rate <1x10 -5 std cc/sec are required to prevent external tritium contamination High degree of redundancy (to provide 24/7 operation) IM RELEASE NUMBER: LLNL-PRES

There are Two Major Groups of Vacuum Systems at NIF: Laser Bay Vacuum Systems and Target Area Vacuum Systems IM RELEASE NUMBER: LLNL-PRES Laser Bays: Spatial Filter Vacuum (SFV) Pre Amplifier Beam Transport System Vacuum (PABTS) PEPC Vacuum (PEV) Target Area: Target Chamber Vacuum (TCV) Final Optics Assembly Vacuum (FOAV) Diagnostics Vacuum (DIAV) Cryo TARPOS Vacuum (CTV) Diagnostics Foreline Vacuum (DFV)

Spatial Filter Vacuum System Features and Vacuum Requirements IM RELEASE NUMBER: LLNL-PRES Vacuum System Features —Forty four large vessels with combined volume ~ 3.3 million liters —7000 ft of piping and tubing —4600 joints —200 actuators for pneumatically operated valves —780 valves used for controlling vacuum, instrument air and cooling water Vacuum System Requirements —Provide less than 10 –4 Torr in Spatial Filter center vessels (needed to control beam distortion at the filter pinhole) —Provide vent to vacuum cycle in four hours —Provide vessel vent with clean, appropriate gas —Prevent particulate disturbance (MIL STD 1246C Level 100 A/10)

Spatial Filter Vacuum Pumping System IM RELEASE NUMBER: LLNL-PRES Four dry pump skids with a Edwards EH2600 blower backed by GV250 dry pump. The pumping speed at the pump is ~600 L/sec. Valves and piping to allow redundant roughing and turbo pump backing conditions for 48 vessels in 2 laser bays. Forty eight 2000 L/s Osaka magnetically levitated turbopumps (one per each vessel)

Target Area Vacuum Systems Overview IM RELEASE NUMBER: LLNL-PRES Target Chamber Vacuum: Designed to pump Target Chamber to less than 5x10 -6 Torr. There are three major subsystems: —Roughing Pumps – Pump TC to < 5 mTorr —Cryogenic Pumps – Pump TC to < 5x10 -6 Torr —Turbomolecular Pumps – Used to leak check TC, or as supplemental high vacuum pumps Diagnostics Vacuum: Designed to pump all diagnostics attached to TC to rough vacuum Final Optics Assembly Vacuum: Designed to rough Final Optics to isolation valves crossover pressure and to support vacuum purge modes Cryo TARPOS (Target Positioner) Vacuum: Designed to rough Cryo TARPOS independently from DIAV Diagnostics Foreline Vacuum: Designed to back up all the Diagnostics turbo pumps

TARGET INSERTION/POSITIONER DIAGNOSTICS FOA T2 MONITOR Tritium Processing System STACK MONITOR Cryo Pump Turbo Pump Rough Pump RP-01/B Rough Pump RP-02 Rough Pump RP- 03/04 Cryo Pump Relief RP RP Rough Pump RP-01/A Rough Pump RP-10905/10925 DFV CTV DIAV DFV FOAV TCV Target Chamber Vacuum DIAgnostics Vacuum Final Optics Assembly Vacuum CryoTARPOS Vacuum/Diagnostics Foreline Vacuum Target Area Vacuum Systems Diagram IM RELEASE NUMBER: LLNL-PRES

Target Chamber Features and Vacuum Requirements IM RELEASE NUMBER: LLNL-PRES Target Chamber features: —Diameter 10 m —Volume ~550,000 L —Material –Body - Aluminum, –1 st wall - Stainless Steel —About 225 Ports —¼ miles of viton seals Vacuum Requirements —Non-cryogenic targets – 5x10 -5 Torr in less than 2 hrs —Cryogenic targets – 5x10 -6 Torr in less than 4 hrs

Target Chamber Roughing Pump RP-01 RP-01 – Consists of three pairs of Edwards Roots blowers in parallel with four mechanical pumps to back them. Combined pumping speed for air ~ 5000 L/sec. Pump has two modules: —RP-01A: Two SVB90 blowers —RP-01B: 2 MHR-622 blowers/2 MHR-615 blowers/4 GV600 dry pumps IM RELEASE NUMBER: LLNL-PRES RP-01 is used to rough Target Chamber, and also to support purge of Final Optics at vacuum

Target Chamber Roughing Pump RP-02 IM RELEASE NUMBER: LLNL-PRES RP-02 – Consists of one Leybold WSU251 Roots blower backed by Busch DP80. Pumping speed ~70 L/sec Pump skid is used to back up Target Chamber turbopumps, and also to regenerate cryopumps

Diagnostics Roughing Pumps RP-03, 04 – Two pump skids with a Edwards EH2600 blower backed by GV250 dry pump (same as Spatial Filter Vacuum). Pumping speed at the pump is ~600 L/sec Pumps skids are used to pump diagnostics from atmosphere to rough vacuum IM RELEASE NUMBER: LLNL-PRES

Final Optics Assembly Roughing Pumps RP-10905/ Two pump skids with a Pfeiffer Octa 1000 AM magnetically coupled blower backed by Busch DP160 screw pump. Pumping speed ~500 L/sec Pumps are used to pump Final Optics Assemblies from atmosphere to pressure required to open isolation valves to the Target Chamber (~250 mTorr) IM RELEASE NUMBER: LLNL-PRES

Cryo TARPOS and Diagnostics Foreline Roughing Pumps CTV/DFV RP-10952/10962 – Single Busch DP600 screw pump for each system. Pumping speed ~170 L/sec CTV pump is used to support Cryo TARPOS operations (roughing, turbopumps backing) DFV pump is used to back Diagnostics turbopumps IM RELEASE NUMBER: LLNL-PRES

Target Chamber High Vacuum Pumps IM RELEASE NUMBER: LLNL-PRES Main Roughing Turbopumps Cryopumps CP-01, 02, 03, 04 – TorrMaster TM900 cryopumps with 36” diameter inlet. Pumps have liquid nitrogen and helium stages. All cryopumps except CP-01 have charcoal on lower temperature (helium) stage TP-01, 02, 03 – Pfeiffer TPH-2301 turbopumps

NIF Vacuum Systems – Major Challenges Air leaks (mostly Target Chamber and attachments) Limited access to equipment due to aggressive operations schedule (means non-interfering maintenance) Aging mechanical pumps Target area mechanical pumps cannot be refurbished by vendor due to tritium contamination Changing operation requirements (continuous evolution of the systems) IM RELEASE NUMBER: LLNL-PRES