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

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

3. 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,

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

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

6. 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,

7. 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,

8. 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,

9. 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,

10. Thank you for your attention