TPSG4 validation at HighRadMat #6

Cedric Baud, B. Balhan, Jan Borburgh, Brennan Goddard, Wim Weterings

Contents

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

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.

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)

SPS LSS4 extraction layout (top view)

TPSG4;3800 kgSPS LSS4: 6 MSE

• Aperture: 20 x 63.5 mm2

• 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

• 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

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]

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 4VINCO718

CfC 1.75Phase 1

Phase 2

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

0 1 2 3 4 5 6 7 8 9 10 11 12

time [μs]

Pow

er d

epos

ition

Present LIU-SPS

Momentum 450 450 GeV/c

Time structure 25ns x 72 x 4 25ns x 72 x 4

Bunch intensity 1.7 1011 2.5 1011 protons

Total intensity 4.9 1013 7.2 1013 protons

Beam size H 0.97 0.75 mm

Beam size V 0.40 0.30 mm

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.

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

Need beam test to see how this fails

CfC anisotropy

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

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

Proposed HighRadMat test set-up

Required:vacuum gauges and ion pumps power supplies, for logging and pumpingwater 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)BLMsOther diagnostics for TPSG – laser vibrometer etc. being discussedInstallation and dismantling under nitrogen flow to achieve good vacuum

TPSG4 (operational spare) MSE (second choice spare)

Pumping module

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 hBeam parameters: 1 mm H, 0.4 mm VBeam intensity: pilot + ultimateIntensity ramped up in steps:

5.1012, 1.1013, 2.1013, 3.1013, 4.1013, 5.1013

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

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