UHV Cleanliness Requirements: Cleaning/Baking and Contamination Control

Transcription

1 UHV Cleanliness Requirements: Cleaning/Baking and Contamination Control Dennis Coyne HAM-SAS Bidder s LIGO Laboratory, Caltech 25 October 2005 Livingston, LA Hanford, WA LIGO R&D 1

2 Basic UHV Compatibility Requirements Cleanliness Requirements:» Achieve a Non-Volatile Residue (NVR) level of A/50 or better (per MIL-STD- 1246C or IEST-STD-CC1246D) on piece parts before clean assembly» Achieve a Particulate Cleanliness Level of 50 or better (per MIL-STD C or IEST-STD-CC1246D) on piece parts before clean assembly» Perform clean assembly and all steps through UHV Packaging in a Class 100 Clean Room (per FED-STD-209)» Comply with Contamination Control Protocols defined in E (M is also a good guide)» Package the Clean Parts per E No Virtual Leaks» Full Penetration Welds No Cold Welding» Stainless fasteners into Aluminum» Silver coated Stainless Fasteners into Stainless» Oversized pilot and tap for tapped holes LIGO R&D 2

3 Ultra-High Vacuum (UHV) Cleanliness Requirements Related to Manufacturing Processes RECEIVE/ INSPECT MATERIALS/ PARTS GROSS CLEANING PER MIL-STD-1246 OR E UHV COMPATIBLE WELDING RESTRICTIONS & FULL PENETRATION WELD CERTIFICATION Notes: (1) The process sequence depicted here is suggestive, and not meant to be prescriptive. (2) Loaded GAS Filter, Spring Blades to be Creep Relaxed in Air Bake REASONABLY CLEAN ENVIRONMENT & HANDLING MACHINE INSPECT PRE-CLEAN INSPECT DIRTY ASSEMBLY - FIT CHECK TUNE UHV COMPATIBLE MACHINING RESTRICTIONS HANDLING/ CONTAMINATION CONTROL PROTOCOL FOR WINDINGS WELD WIND MARAGING HEAT TREAT STRESS RELIEF POTTING WELDMENT MACHINING LIGO LAB QUALIFIES CONTRACTOR CLEANING/BAKING/ CONTAMINATION CONTROL WITH TEST PIECES AND RGA PER E SHIP PACK PARTIAL DISASSEMBLY CLEAN ASSEMBLY (GAS TUNE) FTIR TEST AIR BAKE PRECISION CLEAN DIS- ASSEMBLE UHV PACKAGING PER E (REFERENCE M990034, E960022) CONTAMINATION CONTROL PER E (REFERENCE M990034) CLASS 100 (PER FED-STD-209) FTIR TEST PER MIL- STD-1246 OR IEST-STD-CC1246D TO NVR LEVEL A/50 & PARTICULATE AIR BAKE PER section 5.5 of E (SIMILAR TO E990452) PRECISION CLEANING PER MIL-STD-1246 OR E OR E LIGO R&D LEVEL 100 3

4 Practical UHV Requirements Must pre-clean parts before welding and winding Must clean parts multiple times during fabrication Must thoroughly clean parts!» gross clean with solvents and acids» Mechanical clean (scrub) parts especially tapped holes multiple times, with powered rotary tool during gross and precision clean steps» precision clean with hot, water soluble detergents (steam or hot water spray) multiple times» Never let parts dry with detergent» Multiple rinses with Deionized water Must bake parts (air or vacuum) after precision cleaning Must maintain parts in a class 100 clean room» or keep wrapped in UHV Foil and keep in at least a class 10,000 clean area)» limit exposure, keep wrapped /covered when possible Must Control Contamination with Good Clean Room Practice» All tools must be cleaned, air baked, wrapped & kept in Class 100 areas» All personnel must wear full clean room garb, including hair net, face mask and gloves LIGO R&D 4

5 UHV Requirement References Particulate Level 50 and NVR Level A/50 per MIL-STD-1246C or IEST-STD- CC1246D Cleaning for UHV Service:» Contractor is to certify the cleaning and baking process with representative parts to demonstrate 1246 Level 50-A/50 NVR Level to be confirmed via FTIR (Fourier Transform Infrared analysis) Particulate level to be confirmed by particle sizing and counting or equivalent particle area coverage» LIGO Lab will independently assess the contractor s cleaning/baking process with representative parts by RGA (mass spectrometer outgassing analysis) per E960022» Guidance: E048227, Process Specification for Ad-LIGO Seismic Isolation System In- Vacuum Mechanical Elements: Fabrication (includes cleaning) Contamination Control:» Per E048228, Process Specification for Ad-LIGO Seismic Isolation System In-Vacuum Mechanical Elements: Contamination Control» Additional Guidance: M990034, LIGO Contamination Control Plan FED-STD-209, Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones ISO-14644, Cleanrooms and controlled environments [ISO superceeds FED-STD-209] Packaging:» Per E048227, Process Specification for Ad-LIGO Seismic Isolation System In-Vacuum Mechanical Elements: UHV Packaging LIGO R&D 5

6 Clean Room & Gowning Room Class 10,000 Room Class 100 Clean Room HEPA Filter Gowning Room Sticky Mat LIGO R&D 6

7 HAM Chamber Clean Rooms Full Clean Room Dress Concrete Floor Cleaned Routinely, not ideal, but serviceable LIGO R&D 7

8 UHV Foil Annealed (baked) UHV Aluminum Foil for Wrapping Parts LIGO R&D 8