Test Results of the Cryocatcher Prototype Lars Bozyk

1. Cryocatcher for SIS100 Test Results of the Cryocatcher Prototype Lars Bozyk L.Bozyk, EuCARD'12 annual meeting

2. Outline • Introduction – Dynamic Vacuum • Cryocatcher in SIS100 • Requirements • Design considerations • Prototype Cryocatcher • Test-Setup • Measurements • Results • Summary & Outlook L.Bozyk, EuCARD'12 annual meeting

3. Dynamic Vacuum electron capture adsorbed residual gas dipole desorption electron loss desorption beam loss further charge exchange collimator / ion catcher 2.Mai 2012 L.Bozyk

4. SIS100 Lattice • SIS100 lattice has been optimized to reach a maximum catching efficiency U28+ U29+ • Loss distribution is strongly localized between the quadrupoles where the ion catcher will be installed 2.Mai 2012 L.Bozyk

5. Cryocatcher - Requirements • Desorbed gases must be adsorbed quickly • From lost ions deposited energy has to be removed • Thermal load onto LHe-cooling has to be kept low • Activation of surrounding material should be kept low • Measurement of lost ions desirable • Cryocatcher has to be mounted somehow • Surrounding cold chamber acts as cryopump quickly removing desorbed gases • Cryocatcher has to be kept at a higher temperature to prevent gases from freezing out on the surface of incidence L.Bozyk, EuCARD'12 annual meeting

6. Cryocatcher in Quadrupole Cryostat SIS100 Qaudrupole Cryostat 2.Mai 2012 L.Bozyk

7. Explosive plating – Copper onto stainless steel • Chamber will be coated with copper • Cryo-tests were performed with test-sample Dynaplat, 2010 Reuter, 2010 L.Bozyk, EuCARD'12 annual meeting

8. Cryocatcher - Mounting • Keep cryocatcher at higher temperature (e.g. 77 K) • Direct deposited energy from lost ions into thermal shield cooling (cheaper) instead of magnet cooling • Keep load onto LHe low • Fit into cryostat Heat from lost ions L.Bozyk, EuCARD'12 annual meeting

9. Cryocatcher chamber & CWT L.Bozyk, EuCARD'12 annual meeting

10. Cryocatcher Prototype L.Bozyk, EuCARD'12 annual meeting

11. Cryocatcher Prototype L.Bozyk, EuCARD'12 annual meeting

12. Experimental Test Setup L.Bozyk, EuCARD'12 annual meeting

13. Experimental Test Setup L.Bozyk, EuCARD'12 annual meeting

14. Measurements at the cryocatcher prototype • Pressure measurements • Static pressure • Heavy ion induced pressure rise in the cryocatcher chamber • Temperature measurements • Temperature models • Thermal loads • Dependence of residual gas pressure from chamber temperature • Transition temperatures • Electrical measurements of ion currents L.Bozyk, EuCARD'12 annual meeting

15. Cryocatcher Prototype – Pressure Measurement L.Bozyk, EuCARD'12 annual meeting

16. LHe-Cooldown L.Bozyk, EuCARD'12 annual meeting

17. Cryocatcher Temperature during Beam Impacts L.Bozyk, EuCARD'12 annual meeting

18. Fast beam triggered Pressure Measurement 2·109 Bi-particles L.Bozyk, EuCARD'12 annual meeting

19. Desorption Yields L.Bozyk, EuCARD'12 annual meeting

20. Pressure Rise – Temperature dependence L.Bozyk, EuCARD'12 annual meeting

21. SIS100 cycle simulation L.Bozyk, EuCARD'12 annual meeting

22. Summary & Outlook • SIS100 prototype cryocatcher has been designed, constructed and built • Test setup has been taken into operation and tests with LHe and heavy ion beam have been performed • Cooling-concept showed the desired results in temperature and pressure. • Cryogenic heavy ion induced pressure rise has been investigated, new energy scaling found • Simulation verified the SIS100 cycle stability with measured desorption yields. • SIS100 cryocatcher can be specified on basis of sucessfull prototype L.Bozyk, EuCARD'12 annual meeting

23. ThankYou! • Synchrotron group • Vacuumgroup • Beam diagnosticsgroup • Cryo-magnet group • Central services Questions? Many thanks to several GSI-groups: L.Bozyk, EuCARD'12 annual meeting

24. Backup Slides L.Bozyk, EuCARD'12 annual meeting

25. Scetchofthe prototype testsetup 2.Mai 2012 L.Bozyk

26. Cryocatcher Prototype L.Bozyk, EuCARD'12 annual meeting

27. Cryocatcher Prototype – Pressure Measurement L.Bozyk, EuCARD'12 annual meeting

28. Heat loads onto Cryocatchers L.Bozyk, EuCARD'12 annual meeting

29. Counter Measures for Dynamic Vacuum • Avoid all kind of beam losses  Especially at the beginning of an acceleration cycle (injection) • Lower average static residual gas pressure  Reduce probability for charge exchange • Increase pumping speed at loss positions  Damping of self amplification by fast removal of gas desorption • Install special low desorption ion catcher at loss positions for controlled catching of beam loss  Damping of self amplification by minimizing gas desorption • Desorption yield is lowest for perpendicular incidence • Activation and radiation damage of magnets by ionization beam loss are reduced L.Bozyk, EuCARD'12 annual meeting

30. Cryocatcher - Chamber • Inspired from SIS18 ion catcher: • Increased diameter compared to flange diameter • Secondary chamber plates to reduce vacuum conductance to beam axis • Additional requirements: • Pumping port for arc roughing necessary • Passive cooling desired • Limited space due to common girder L.Bozyk, EuCARD'12 annual meeting

31. Ionization Loss Mechanisms • Cross section for charge exchange depends on energy, ion, charge state and residual gas composition L.Bozyk, EuCARD'12 annual meeting

32. Thermal Conductivities L.Bozyk, EuCARD'12 annual meeting