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) TPSG4;3800 kg SPS LSS4: 6 MSE

6. Aperture: 20 x 63.5 mm 2 Water cooled copper conductor Vacuum 5.10 -9 mbar MSE 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. Absorber blocks are edge cooled to cope with continuous losses Dry weight 3800 kg Under vacuum, operating pressure in 10 -9 mbar range TPSG4 Active length: 3000 mm RP shielding under vacuum

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 CfC composite 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 Ti 6Al 4V INCO718 CfC 1.75 Phase 1 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 PresentLIU-SPS Momentum450 GeV/c Time structure25ns x 72 x 4 Bunch intensity1.7 10 11 2.5 10 11 protons Total intensity4.9 10 13 7.2 10 13 protons Beam size H0.970.75mm Beam size V0.400.30mm

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.  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 CfC greatly 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  The CfC greatly 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 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 TPSG4 (operational spare) MSE (second choice spare) Pumping module

16. Beam conditions Ideally, proton beam: 1.7.10 11 /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: 5.10 12, 1.10 13, 2.10 13, 3.10 13, 4.10 13, 5.10 13

17. Post-irradiaton analysis 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 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.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.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 2007Workshop 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, EdinburghJ. Borburgh et al., “MODIFICATIONS TO THE SPS LSS6 SEPTA FOR LHC AND THE SPS SEPTA DILUTERS”, EPAC2006, Edinburgh