1. TDI Coating test at HiRadMat Proposal HiRadMat Scientific Board Meeting 27th June I. Lamas Garcia, M. Calviani, R. Ferreire, A. Perillo-Marcone
27 June 2016
I. Lamas Garcia – EN-STI

2. Presentation Scope TDI General Considerations TDI Coating Issues
Proposed HiRadMat Test
Experimental Setup
Beam Requirements
27 June 2016
I. Lamas Garcia – EN-STI

3. TDI General Considerations
What is a TDI?
Target Dump Injection.
Where is located?
At the 2 injection points in the LHC lines (P2 & P8).
What is its function?
Protect the downstream equipment and experiments from a kicker malfunction during injection phase from SPS to LHC.
What are its operating conditions?
450 GeV protons are injected in 2, 3 or 4 batches of 72 bunches up to 1.7·10E11, with normalized horizontal and vertical emittances of 3.5 mm.mrad.
27 June 2016
I. Lamas Garcia – EN-STI

4. TDI General Considerations
27 June 2016
I. Lamas Garcia – EN-STI

5. TDI Coating Issues
Several issues related to the TDI performance during operation were found (i.e. deformation due to heating caused by high resistive wall, spurious vacuum spikes).
There were reasons to believe that these issues were caused by:
Quality non-conformities on the upstream low density absorbing blocks made of hexagonal boron nitride (hBN).
Damage on the 5 um Ti coating present on these blocks in order to reduce the resistive heating.
Jaw deformation correlated by LVDT drift
Spurious vacuum spikes
27 June 2016
I. Lamas Garcia – EN-STI

6. TDI Issues & Modifications Timeline
Run 1
Issues:
Beam Induced RF heating
Cu beam screens deformed
Thermal drifts measured by LVDTs
Outgassing during fills (TDI.4L2)
LS1
Modifications:
Reinforced St. Steel beam screen
Improved sliding contacts
NEG cartridges
Ti coating on Al envelopes
Temperature sensors
2015 (scrubbing & physics)
Large vacuum spikes during injection (TDI.4R8)
Spurious spikes during fills with jaws retracted
Notorious different behavior between TDIs (temperature readings, transverse impedance and synchronous phase shift)
YETS 2015/2016
TDI Spare Consolidation:
Quality issues with hBN blocks (binder material)
Replacement hBN for Graphite R4550 sputtered with Cu
Better cooling circuit contact
Refurbishment of the jaw displacement mechanism
Interferometric system
Run 2
So far:
Impedance measurements show big improvement
Good vacuum behavior during injection
Large vacuum spikes when retracting the jaws above 40mm half gap
Still notorious different behavior between TDIs
27 June 2016
I. Lamas Garcia – EN-STI

7. TDI Coating Issues
It was decided to condition accordingly the TDI Spares and exchange them during the YETS 2015/2016. The TDI Spares were subjected, between others, to the following modifications:
- Longer low density absorbing blocks made of Graphite SGL R4550
- The blocks have been sputtered with 2 um of Cu to reduce resistive heating
Resistive Power losses at different absorbing blocks material (w and w/o Cu coating) and energy
N. Biancacci et al. at LMC #215
27 June 2016
I. Lamas Garcia – EN-STI

8. TDI Coating Issues
Severus damage on the Ti coating was found after dismantling (10/01/2016):
Cu coating on graphite blocks for the TDI Spares (14/09/2015):
27 June 2016
I. Lamas Garcia – EN-STI

9. Proposed HiRadMat tests
Given the past issues and the general uncertainties on coatings behavior when grazed by a high intensity proton beam, there is a high priority recommendation by the LHC Machine Committee (LMC#256) to test and validate the sputtered Cu performance under the same impact conditions that the TDI could face during Run 2.
In order to gain important information for other BIDs, TDI coating configurations will be tested on low-Z materials such as SGL R4550 and Tatsuno 2D CfC.
As part of a bigger R&D that STI is conducting and given the extra jaw available in the HRMT 28 tank, an absorber block made of Polycrystalline Silicon will be tested under direct impact of different proton beam pulses.
Polycrystalline Silicon has the advantage of a very low degassing rate on UHV conditions. It is slightly denser than graphite, so could be potentially very interesting for dilution in devices such as the TIDVG. The goal would be to asses the PS behaviour without going above any damaging point, thus eliminating the risk of compromising the rest of the experimental set up.
27 June 2016
I. Lamas Garcia – EN-STI

10. Proposed HiRadMat tests
The main goal of the experiment is to assess if the structural integrity of the sputtered Cu is compromised under grazing beams with small impact parameters.
This can be verified by visual inspection without opening the tank, even during the experience.
Post-irradiation test are foreseen (timing details to be agreed with HSE/RP):
Metrology measurements
Ultrasound tests
Microscopy analysis
Electrical resistivity measurements
This results will be compared with the results of the tests performed before the experience on the absorbing blocks.
Results will be key to validate not only the Cu coating, but the graphite itself as substrate.
27 June 2016
I. Lamas Garcia – EN-STI

11. Experimental Set Up
The HRMT 28 tank and test bench will be used for this experiment
Modifications will be performed on the jaw configuration in order to host up to 4 different absorbing materials and coating configurations:
SGL Graphite R4550 TDI coating configuration with Cu coating
Tatsuno 2D CfC in a TDI configuration with Cu coating
Polycrystalline Silicon (w/o Cu coating)
27 June 2016
I. Lamas Garcia – EN-STI

12. Experimental Set Up
The vertical jaws will be accommodated in a vacuum-tight tank to avoid any possible contamination of the surrounding area
The top cover will be equipped with glass window permitting a visual inspection of the internal equipment
Design is compatible with the installation on a standard HiRadMat table
HRMT 28 assembly. Prior to the 72 bunches filling restriction, the experiment went exceptionally fine. First results are very promising.
27 June 2016
I. Lamas Garcia – EN-STI

13. Experimental Set Up Tank will be equipped with Be beam windows
Tank will be leak tight and under primary vacuum to mitigate the risk of fire
The jaws will be movable on the vertical plane, while the tank itself can be moved horizontally
27 June 2016
I. Lamas Garcia – EN-STI

14. Experimental Set Up Measurement methods will be:
BPKG right upstream of the jaws in order to accurately monitor the beam position and verify the impact parameter
Online visual inspection by means of 4-5 radiation resistant cameras
Pyrometer and/or thermocouples to measure the temperature of the jaw frame and the absorbing blocks
2 BLMs to monitor beam losses during alignment of the beam and during grazing impact
27 June 2016
I. Lamas Garcia – EN-STI

15. Beam Requirements Beam Parameters:
The accuracy of the beam parameters is a critical aspect on this experiment.
27 June 2016
I. Lamas Garcia – EN-STI

16. Beam Requirements Experimental time:
- The equipment will be pre-installed and aligned on the HiRadMat table while on surface (867 and BA7). Its placement in the experimental area will take few hours.
Beam time:
Beam base alignment. 10 alignment scans per jaw are foreseen. Time estimated for alignment is around 4 hours in total.
Maximum 24 beam pulses are foreseen per jaw, all with the same bunch configuration.
Grazing impact on 3 different surface points on coated jaws while direct impact for the Polycrystalline Silicon jaw.
Time estimated between shots is around 10 minutes, in order to allow inspection of acquired monitoring data and cool-down.
Once room temperature is reached, the concerned jaw will be moved horizontally to provide a new surface for consecutive shots.
27 June 2016
I. Lamas Garcia – EN-STI

17. Thank you!
01 March 2016
I. Lamas Garcia – EN-STI