Goal Oriented Training Programme ITER Port-Plug Engineering

1. Goal Oriented Training ProgrammeITER Port-Plug Engineering Status of the work performed in WP3 Trainee: Gaetano Aiello Supervisor: Theo Scherer 1 | PPE meeting – Cadarache, 7 December 09 G. Aiello

2. WP3 overview Topic: materials, manufacturing and assembly of upper port plug structures. Start: 1st September 2008 • Main performed activities: • To get knowledge on design and simulation tools (Catia, ANSYS) example of Computational Fluid Dynamics (CFD) analysis. • Experimental study of the outgassing of SS, CuCrZr and Be samples in vacuum at elevated temperatures (in progress). 2 | PPE meeting – Cadarache, 7 December 09 G. Aiello

3. The Upper Launcher (UL) in ITER Main structure BSM The main structural material is SS 316L(N)-IG. Normal condition: T=120-150°C Bakeout condition: T=240°C Gas released from the material contaminates the ITER plasma and affects the vacuum quality! 3 | PPE meeting – Cadarache, 7 December 09 G. Aiello

4. Internal auxiliary shield Internal main shield Closure plate Front shield Waveguides Quasi optical mirrors Cooling feed pipes Focusing mirrors Steering mirrors Vacuum in the UL • UL is in-vessel component. The internal vacuum components are mm-wave components, cooling devices and elements for nuclear shielding. • Vacuum is created from the cut-out in the BSM and a pressure of 10-4 mbar is required between the two internal shields. Closure plate is the vacuum boundary. • The surface exposed to the vacuum is approximately: • UL outer shell ~ 19 m2 • UL inner shell ~ 13 m2 • waveguides ~ 5 m2 • front, main and auxiliary shields ~ 8.5 m2 4 | PPE meeting – Cadarache, 7 December 09 G. Aiello

5. Outgassing • Outgassing is gas desorbed from a vacuum surface due to the temperature of the surface [ITER Vacuum Handbook]. • The specific outgassing rate (Q) is the amount of gas leaving the material per unit of time and per unit of exposed surface at a specified time after the start of evacuation, so units of measurement are Pa m3 s-1 m-2. Measurements of partial specific outgassing rates are in progress for several SS-samples, produced with the preferred manufacturing routes. 5 | PPE meeting – Cadarache, 7 December 09 G. Aiello

6. SS-samples SS 316 LN by P HIPing 3 pairs SS 317 LNMby Rolling SS 317 LNMby Rolling + HIPing In each pair: Polished sample Sample with rills 6 | PPE meeting – Cadarache, 7 December 09 G. Aiello

7. Roughness measurement - 1 By optical method, raw data related to an area of 1 mm2 are obtained. Polished sample Sample with rills Roughness and waviness are distinguished by the cut-off length λc,whose value is suggested by the normative. 7 | PPE meeting – Cadarache, 7 December 09 G. Aiello

8. λc=0.029 mm, λ<λc. Roughness and waviness are distinguished. λc=0.143 mm, λ<λc. Waviness is counted in the roughness profile. Roughness measurement - 2 Purpose: determination of the surface factor of each sample Roughness profile and parameters  Same result as !  2 tests were made for SS 316 LN The surface factor is calculated as in the polished case: 8 | PPE meeting – Cadarache, 7 December 09 G. Aiello

9. Selected method for measuring the outgassing P2 P1 C Sample Vacuum chamber Pumping station • Dynamic flow method: • Variant dynamic flow method: if the conductance (C) is much lower than the pump speed (Sp), P2 is negligible with respect to P1 and therefore: This formula is used in the experiment, being Sp≈30C. Partial specific outgassing rates may be determined by measuring the partial pressures with a mass spectrometer. 9 | PPE meeting – Cadarache, 7 December 09 G. Aiello

10. Vacuum test setup P.I.D. V.G. O. Q.T. T.M.P. M.P. The lowest pressure that can be obtained is 1*10-7 mbar. 10 | PPE meeting – Cadarache, 7 December 09 G. Aiello

11. Temperature calibration in air Comparison at atmospheric pressure of the temperature readings between the PID controller and a K-thermocouple inside the quartz tube. Calibration in the mid-point of the oven. TC sampling rate is 1 Hz and mean values are calculated on 30 minutes. 11 | PPE meeting – Cadarache, 7 December 09 G. Aiello

12. Temperature calibration in vacuum - 1 Temperature measurements in the mid-point of the oven at the pressure of 1*10-7 mbar. Air natural convection has a negative effect on the calibration curve! 12 | PPE meeting – Cadarache, 7 December 09 G. Aiello

13. Temperature calibration in vacuum - 2 Sample 13 | PPE meeting – Cadarache, 7 December 09 G. Aiello

14. Mass spectra in blank runs - 1 Experimental setup at the pressure of 1*10-7 mbar. Vacuum baking of the setup is necessary before the outgassing measurements. 14 | PPE meeting – Cadarache, 7 December 09 G. Aiello

15. Mass spectra in blank runs - 2 The peaks have been fitted by the Gaussian function. Results are shown for the H+ peak. The vacuum vessel base pressure has to be <10-5 Pa for hydrogen prior to ITER operations at the operating temperature of 100°C [ITER Vacumm Handbook]. 15 | PPE meeting – Cadarache, 7 December 09 G. Aiello

16. Next steps • Scan analog measurement by the mass spectrometer is not suited to determine the partial pressures because of poor statistical accuracy and overlapping ion currents of differing origin on the same mass numbers. • The partial specific outgassing rates can be calculated, provided that the temperature dependent conductance is known for the several gas species traversing it. Calibration of the mass spectrometer to determine its sensitivity for each expected gas species in the experiment. Multiple Ion Detection (MID) measurement by the spectrometer for blank and sample runs: the ion current is measured only on the masses of interest. The measured ion currents are input to a system of linear equations and the partial pressures are determined via sensitivities of the spectrometer. 16 | PPE meeting – Cadarache, 7 December 09 G. Aiello

17. Outgassing limits and backing • In the ITER Vacuum Handbook the maximum steady state specific outgassing rates at 100°C are 1*10-7for the hydrogen isotopes and 1*10-9 Pa m s-1 for the impurities. • Example: the measured specific outgassing rate of 300 series SS for H2, after baking under vacuum for 25 h at 300°C, is 2.8*10-7 Pa m s-1 at 100°C. Only after two further thermal cycles (baking + temperature rise), the outgassing falls down to 5.2*10-8 Pa m s-1 at 100°C [Elsey, Calder, Lewin]. • The vacuum baking conditions for the UL are 24 h at 240°C [ITER Vacuum Handbook]. • It is difficult to respect the limits. • The baking conditions might be revised in accordance with the limits. 17 | PPE meeting – Cadarache, 7 December 09 G. Aiello

18. Example of static CFD analysis Geometry Mesh Pre-processing Post-processing 18 | PPE meeting – Cadarache, 7 December 09 G. Aiello

19. Other activities • Attended conferences and training courses: • 2nd Summer school on fusion technologies (KIT, September 2008); • Catia and Smarteam courses (KIT, December 2008); • Russian-German Workshop on ECRH and Gyrotrons (Greifswald, May 09); • Training session about vacuum in fusion environment, tritium and remote handling, project management, optical diagnostic (Culham, June 2009); • Vacuum outgassing meeting (Cadarache, July 2009); • Writing in English – a Workshop for Scientists and Engineers (Karlsruhe, 3-4 December 2009). • Planned training courses: • Effective Negotiations (Karlsruhe, June 2010); • Basic International Project Management (Karlsruhe, October 2010); • Advanced International Project Management (Brussels, December 2010). 19 | PPE meeting – Cadarache, 7 December 09 G. Aiello

20. Objectives for the 2nd year of training BSM Corner prototype 20 | PPE meeting – Cadarache, 7 December 09 G. Aiello