1. Vacuum assessment for BI equipment TE-VSC

2. Why do we need to assess BI components 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 2 The main mandate of TE-VSC is to guarantee the quality of the vacuum in CERN’s accelerators. TE-VSC is responsible for the vacuum results of all installed components. Assessment is needed and in more than one step: Leak tightness. Contamination. Outgassing rates (and its time variation). Virtual leaks. The TE-VSC group leader is responsible for the impact of any installed components on the vacuum of our accelerators.

3. Absence of leaks 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 3 He leak rate acceptance threshold: 10 -10 mbar l s -1 The leak detection has to be carried out by TE-VSC personnel or authorized subcontractors. He leak rate beyond the threshold are not acceptable, despite the fact that the resulting pressure is compatible with the application. Leaks are signs of defects in the material and its assembly; progressive deterioration cannot be excluded.

4. Detection of contamination 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 4 What do we consider as contamination: Anomalous presence of hydrocarbons: → Inadequate cleaning (error in cleaning procedure, post- cleaning pollution…). → Inappropriate choice of materials (polymers, glues, lubricants, …). Higher than expected CO and CO 2 pressures: → Indication of carbonized elements. How do we consider contamination thresholds: They are represented by RGA peaks normalized to the dominant gas peak (18 amu in unbaked system, 2 amu in baked) The upper limits originate from previous experiences (see EDMS 1347196 v.1), beam-gas interaction concerns (Z 2 ), and effects on the pumping systems (NEG).

5. Contamination: acceptance thresholds 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 5 Unbaked beam lines Reference peak is 18 amu (water vapour)

6. Contamination: acceptance thresholds 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 6 Not conform Unbaked beam lines Reference peak is 18 amu (water vapour)

7. Contamination: acceptance threshold 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 7 Baked beam lines Reference peak is 2 amu (H 2 ) H2H2 CH 4 CO CO 2

8. Outgassing rates 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 8 The acceptable outgassing rates depend on the pressure requirement and the available effective pumping speed. The first is a constraint of the accelerator and on the place of installation. The second varies from point to point in the accelerator. Average values can be given for both.

9. Outgassing rate limits: the LHC 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 9 Pressure requirements with beams: Arcs: 10 -8 mbar Experimental areas: 10 -10 -10 -11 mbar Effective pumping speed: Strongly dependent on position; generally higher than 100 l s -1. Outgassing rate threshold: Less than 10 -7 mbar l s -1 for the dominant gas (H 2 )

10. Outgassing rate limits: the injectors 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 10 The injectors are in general not baked; consequently, the achieved pressure is a function of time (t -1 ) for months. The assessment is less obvious than for the LHC. Preliminary acceptance criterion: the pumpdown slope in log(P) vs. log(t) has to be lower than -0.8.

11. Outgassing rate limits: the SPS 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 11 Arcs: Required pressure: 3.10 -7 mbar after 24 h pumping. Effective pumping speed: 10 l s -1 in average. Outgassing rate threshold: 10 -5 mbar l s -1 after 10 h of pumping LSS (kickers, septa, cavities, …): Order of 10 -8 mbar after 24 h pumping. Effective pumping speed: 100 l s -1 Outgassing rate threshold: 10 -5 mbar l s -1 after 10 h of pumping For info: the limit value is equivalent to the outgassing rate of 10 m 2 of stainless steel. Stringent?

12. Outgassing rate limits: the PSB and LINACS 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 12 Same exercise, same result: Outgassing rate threshold: 10 -5 mbar l s -1 after 10 h of pumping

13. Outgassing rate limits: the PS 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 13 Required pressure for protons: < 10 -7 mbar Required pressure for ions: < 10 -8 mbar Specific pumping speed: 70 l s -1 m -1 in average. Outgassing rate threshold: 5.10 -6 mbar l s -1 after 10 h of pumping No venting allowed weeks before the ion runs.

14. Virtual leaks 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 14 The tolerated virtual leak rate is lower than 5.10 -9 mbar l -1 s -1 for all accelerators. In the LHC, such a leak would saturate 1 m long NEG coated chamber every 150 days.

15. Spare parts 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 15 VSC is responsible of all components beyond the boundaries of the inserted pieces of equipment. The equipment owners are in charge of their spare parts and updated stocks. VSC can order for the equipment owners the vacuum components if required. To be defined if we want to have a spare chamber for each device; our proposal: 1.NEG coated or simple SS spare chambers for all devices in LHC 2.Injector complex: Spare components available that could be prepare in a short period of time: max of 2 days For dedicated devices (critical): Spare chambers

16. VSC design-approval meeting 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 16 To validate the mechanical design of equipment to be installed in the vacuum system, a working group is set to review the drawings. On request of the technical responsible, who provide relevant information, it makes recommendations based on different criteria: General layout (fixed/sliding points). Mechanical design (Vacuum chambers, bellows, RF fingers, supporting system, connections,…). Standardisation of components and methods. Compatibility with existing system. Fabrication (feasibility, compatibility with surface treatments). Installation and operation: accessibility, tooling (remote handling), radioprotection aspects. Vacuum material.

17. Concluding remarks 10/6/2015 BI Beam Operational Spare Strategy Workshop No 2 17 TE-VSC ensures the required level of vacuum for our accelerators. The responsibility for intolerable high outgassing components is ascribed to TE-VSC. Assessment tests are mandatory for our components as for those of the other groups. TE-VSC aims at tightly collaborating with BE-BI and other groups that own essential equipment in the accelerators. We are available to help you in the design and production phases so that surprises are avoided at the assessment tests. If a piece of equipment is not accepted, we provide you with our full support to solve the issue as soon as possible.

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