Operating SRF systems reliably in a “dirty” accelerator Creating clean conditions outside of a cleanroom Birte van der Horst Berlin, 15.09.2017

Project European XFEL Basic informations 800 Cavities 100 modules Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Leaks of modules during production 3 of them showed leaks on cold components after intensive inspection and quality control before acceptance for installation in the tunnel Due to time restriction and continuity of production the exchange of these parts needed to be done without reentering the cleanroom. Repair of these modules took place by setting up a local cleanroom onto the cavity string Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Cleanroom tent (CRt) Cleanroom foil is used for implementation Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Filter fan unit (FFU) Vertical FFU was used to guarantee cleanroom conditions Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Realization of CRt Before repair Size of CR was defined Vertical filter fan unit (FFU) was buildt up in front of the defect component of the cavity It has to be set up behind the defect component.Partikulates which are produced by movements from the operator are carried away from the object of repair Cleanroom foil was wrapped around area of repair, gaps were sealed Foil was cleaned with particle filtered ethanol from inside and particle contamination of surfaces was checked N2 air fogger was used to check a laminar air flow Velocity of air was measured to ensure blow off dust from repair area Cleaning of all components for the repair procedure was done in conventionel CR and wrapped double into foil (Tools, gaskets, screws, HOM-coupler a.s.f.)  Components brought into CRt Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Quality control of the cleanroom To ensure cleanroom quality velocity and directed air flow were checked N2 air fogger Air velocity sensor Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Cleanroom CRt For good results before opening the connection overpressure with N2 is applied to the cavities Fully equiped CRt Prepared area for the repair procedure Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

Working plan Repair procedure Essential requirement! Operator working in cleanroom clothing (Unisuit, cap, mouth protection, gloves) Particle counter is installed Ionized N2 is available for cleaning components from outside Cleaning of components with particle filtered ethenol , wrapped double into foil, from outside (Tools, screws, HOM- coupler) Unwrap first foil, clean second foil with particle filtered ethanol and N2 Essential requirement! Permanent nitrogen overpressure from inside of string is needed to guarantee minimized particle contamination of string Realized and checked by MVS vacuum group Clean of the area with leak component ,with particle filtered ethanol and blown with ionized N2 air gun Open connection (Working instruction is availlable, if needed) Change component Pump down new connection Leak check, residual gas analyses (RGA ) Reassemble Module Creating clean conditions outside of a cleanroom Birte van der Horst, 15.09.2017

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