http://www.surfacetreatments.it/thinfilms Presence of Residual Tin drops on Thermally Diffused Nb3Sn (Atroschenko Konstantin - 10') Speaker: Atroschenko Konstantin - INFN-LNL | Duration: 10 min.

1. "Presence of residual Tin drops in Thermally diffused Nb3Sn" Authors: Konstantin Atroshchenko Antonio Alessandro Rossi Supervisor: prof. Enzo Palmieri

3. uniformity of the film (stoichiometrically);

4. can be used for covering surface of wide and complex shaped substrates (!).

8. Diffusion of contaminations through the wall of the chamber at high temperaturesexternal furnace cavity droplets of Tin vacuum chamber

9. Residual Tin drops on the internal and external surface of the cavity External surface Internal surface Sn Nb3Sn Sn

10. The L - samples 15 For the experiment was designed the L-samples, which imitates the shape of the cavity. Samples is made of Niobium. 3 50 10

12. washing in deionized water with ultrasonic

13. washing with deionized water

14. drying with nitrogen

15. BCP in the solution: HF/HNO3/H3PO4 = 1/1/2

16. washing with deionized water

18. Glow Discharge. Results. Flange Ceramic tube Sample After dipping and annealing @ 1000oC Horizontally fixed sample Nb wire Glow discharge. View from the bottom window After glow discharge

19. Preparing the surface. Anodization Procedure: Ultrasonic + Rodaclean 60 min sample Clean with acetone Ammonium citrate Clean with alcohol BCP 10 min To the power supply After anodization After dipping and annealing @ 1000oC Anodization in ammonium citrate. V = 20V Annealing. 4 hours. T = 1000OC

20. Preparing the surface. Chemical etching Procedure: Ultrasonic + Rodaclean 60 min Clean with acetone Clean with alcohol Chemical etching HNO3 : HF = 1 : 1 After annealing After etching

21. Comparison of external resistive and internal heaters

22. Internal heater high temperature annealing The cross-section of the system: Linear feedthrough L - samples Hot zone heater Cold zone Vacuum chamber Pumping out

23. Vacuum Chamber Whole – metal valve Vacuum chamber Pumping control unit Gate switch baking control unit Temperature control unit

24. Comparison of annealing at 1000OC and 1300OC annealing at 1300OC for 5 minutes annealing at 1000OC for 4 hours Just BSP anodization etching glow discharge

26. SEM measurements

27. Profilometric measurements

28. Covering of the Nb 6 GHz cavities;

30. Phase diagram of Nb - Sn

31. Short theoretical part The theoretical explanation of the process is basis on the Fick’s first law In two or more dimensions we must use the operator, which generalizes the first derivative, obtaining

33. time of treatment: 5 min

34. maximum rf - power: 5 kW

35. process temperature: 1200 – 1500OCfeedthrough (Nb) wave – guide coil samples vacuum chamber sample after annealing

36. High – temperature annealing heater

37. Heating of the 6 GHz cavity