TPSG4 validation at HighRadMat #6

1. TPSG4 validation at HighRadMat #6 Cedric Baud, B. Balhan, Jan Borburgh, Brennan Goddard, Wim Weterings

2. Contents • Scope • Diluter calculations • Validations of calculations • Beam conditions • Post irradiations steps • References

3. Scope 2 types of septa protection elements exist in the SPS: • TPSG4, diluter to protect thick MSE septa in LSS4 SPS • TPSG6, diluter to protect thin MST septa in LSS6 SPS The first to be constructed and installed was TPSG4 phase 1 (in 2003). Developments from work on TCDS and TPSG6 showed that upgrade was needed for TPSG4 as well (phase 2, installed 2005) [5]. LIU-SPS beam parameters now available – more challenging for these protection devices (a phase 3 will be needed). All designs are based on simulations – need benchmarking.

4. Purpose of TPSG’s • Protect Magnetic septa (MS downstream) from damage by the beam. • Protect MS copper coil from being deformed → ΔT <80 K • Limit water pressure rise in cooling channels of MS coil ΔP < 25 bar (tpsg6 to protect thin septum MST) (→ ΔT < 8 K) ΔP < 50 bar (tpsg4 to protect thick septum MSE) (→ ΔT < 15 K)

5. SPS LSS4 extraction layout (top view) SPS LSS4: 6 MSE TPSG4;3800 kg

6. MSE • Aperture: 20 x 63.5 mm2 • Water cooled copper conductor • Vacuum 5.10-9 mbar • Cooling flow per magnet: 160 l/min • Water speed in septum: 9 m/s • Operating water pressure: 24 bars • Weight of full tank 2270 kg • Static water pressure test: 80 bars • Bake-able at 150°C

7. TPSG4 • Active length: 3000 mm • RP shielding under vacuum • Absorber blocks are edge cooled to cope with continuous losses • Dry weight 3800 kg • Under vacuum, operating pressure in 10-9 mbar range

8. Diluter calculations • Nuclear calculations were done at CERN • Thermal and mechanical dynamic calculations were done at CRS4 (Sicily) [2,3] • Results were presented workshop on Materials for Collimators and Beam Absorbers (3-5 September 2007) @ CERN [4]

9. TPSG4 beam diluter • In the first design (phase 1) the TPSG4 was 3.0 long and had the following material composition: 2.4m of graphite, 0.3m of a titanium alloy, and 0.3m of a Nickel based alloy • The design has then been modified by substituting several graphite blocks with a CfCcomposite and by adding another 10cm long graphite block • The three section were composed of several blocks each having a cross section of 30 x 19.25 mm, the block length is 240-300mm CZ5 Phase 1 CfC1.75 Ti 6Al 4V INCO718 Phase 2

10. TPSG4 beam load • For the purpose of the analysis, the LHC ultimate beam intensity is considered as the worst case • Intensity will increase with LIU-SPS (for HL-LHC), to around 2.5e11 p+/b, and beam sizes will also be smaller (0.75 and 0.30 mm in H/V) with reduced emittance

11. TPSG4 phase 2 results: diluter temperature increase • The temperature increase is similar to the results of phase 1 • The max ΔT is found in the 1st and 2nd blocks, the beam is also highly focalized • The additional graphite block in phase 2 compensates the effect of the lower density of CfC.

12. TPSG4 phase 2 results: max Stassi ratio • The CfCgreatly reduces the resulting equivalent stresses • The results are acceptable for the graphite block, are well below the failure limit for the CfC • The stress ratio is high for the Ti and Inconel blocks, but these alloys have a ductile behavior Need beam test to see how this fails

13. CfC anisotropy Young’s modulus for the TCDS materials as a function of the temperature (detail)

14. Validation of calculation • Presently several extraction protection equipments are installed in SPS and LHC (TPSG4, TPSG6, TPSN, TCDS, TCDQ). • Protection of the downstream equipment relies fully on effectiveness of these diluters! • All designs are based on simulation results. • High energy variants (as in use in SPS and LHC) use CfC and graphite, with non isotropic mechanical properties. • Validation of design is required: • for the behaviour of the non isotropic CfC • for the assumption that exceeding the Stassi limit for ductile materials is acceptable (Ti and Inconel blocks) • To demonstrate the MSE is properly protected by TPSG4

15. Proposed HighRadMat test set-up Pumping module MSE (second choice spare) TPSG4 (operational spare) • Required: • vacuum gauges and ion pumps power supplies, for logging and pumping • water pressure in MSE coil (24 bar) (MSE not powered, so no real cooling needed, but water under pressure needed, logging only possible at the coil entrance) • BLMs • Other diagnostics for TPSG – laser vibrometer etc. being discussed • Installation and dismantling under nitrogen flow to achieve good vacuum

16. Beam conditions Ideally, proton beam: 1.7.1011/bunch, 288 bunches, 3.75 μm, 1.0 mm H x 0.4 mm V Requested beam time: 4 h Beam parameters: 1 mm H, 0.4 mm V Beam intensity: pilot + ultimate Intensity ramped up in steps: 5.1012, 1.1013, 2.1013, 3.1013, 4.1013, 5.1013

17. Post-irradiatonanalysis steps • Evaluate data logged during test (vacuum, pressure, temperature, intensity, BLM’s). • ALARA analysis needed • Leak test of MSE coil • Disassembly of TPSG4: inspection of absorber blocks • Repair of TPSG4, as needed • Renovate MSE

18. References [1] HighRadMat experiment request, https://espace.cern.ch/hiradmat-sps/Beam%20Requests/HiRadMat_BeamRequestSurvey_HRM6_TPSGRP.docx [2] L.Massidda and F. Mura, “Dynamic Structural Analysis of the TPSG4 & TPSG6 Beam Diluters”, CRS4, Cagliari, Italy, June 2005. [3] L.Massidda and F. Mura, “Analysis of the Water Dynamics for the MSE-Coil and the MST-Coil”, CRS4, Cagliari, Italy, June 2005. [4] Workshop on Materials for Collimators and Beam Absorbers, CERN, 3-5 September 2007 [5] J. Borburgh et al., “MODIFICATIONS TO THE SPS LSS6 SEPTA FOR LHC AND THE SPS SEPTA DILUTERS”, EPAC2006, Edinburgh