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Injection Region Review
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Europe/Zurich
61/1-017 - Room D (CERN)
Injection Region Review
Present: Patric, Edda, Justin, Jim, Daniel, Marlene, Michele (partially), Tobias (partially)
General / Layout
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Diagnostics section just downstream of the 150 MeV electron beamline waist.
The section could be made longer while maintaining the total length by shortening the APC. -
There will be a CERN sector valve downstream of the 2nd plasma.
Question: should we also add a sector valve on the 3rd expansion volume?
Action: GWA to check whether it would fit. -
The proton beamline will connect to the first plasma source with an incoming angle of 0.9 mrad.
There is no single bellow upstream of the vapor source that needs to accommodate this angle. -
Injection dipole aperture is currently 100 mm, and the aim is to keep it unchanged.
Action: MT to confirm with Vittorio. -
Chillers:
Action: MT to determine how much smaller the streak room needs to be. -
Locate where the vapor source Gen1 mu-metal is stored.
Action: MT to contact Philip Schwarz. -
The bellow upstream of the vapor source will need to absorb more than twice the thermal expansion of the vapor source, since the system is now longer.
Action: MT to check with Maria Carmen on the current plan. -
Commissioning chamber: preferable if it can slide in and out.
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Action: GWA to send volume estimates to Maria Carmen for vacuum simulations (vacuum levels in the vapor source).
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GWA cannot edit Fred’s model.
Action: GWA to ask Fred for a different STEP file variant.
Action: MT to follow up if needed.
Beam Waist Diagnostics
(Both options may require multiple-shot measurements.)
Option 1: Screen + lens + camera
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Can the lens handle the high temperature, or can it be cooled sufficiently without creating a cold spot or large thermal gradient in the main source?
Action: GWA to investigate with thermal simulations. -
Will the cone-shaped OTR light emission pattern cause issues?
Action: PM and MB to investigate. -
Will the finite size of the screen limit resolution?
Action: PM, MB, and MT to investigate. -
Consider using a reflective telescope.
Action: PM, MB, and MT to investigate. -
Should the lens and camera be mounted on a translation stage, possibly with x/y/z motion?
Action: All to investigate. -
Can a focal scan be implemented?
Required travel range: ~10 mm along the beam waist.
Action: All to investigate. -
Beam alignment: how will the beam be found and aligned?
Action: PM, MB, and MT to investigate.-
What is the minimum change in dipole B-field, and how far does that move the beam?
Action: MT to check with BE-ABT.
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Known risks and mitigation:
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Insufficient resolution / two-cone emission → Theory calculations
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Lens overheating → Thermal simulations
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Cold spot in the main system → Thermal simulations
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Difficulty finding the beam
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Alignment challenges → Prototype testing
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Screen size limitations → Calculations
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Manufacturability → CAD studies
Option 2: Wire Scanner
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Aperture of prongs on the order of 2 mm.
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Can temperature effects be decoupled from motion?
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Significant expertise available at PSI; collaboration needed for fabrication of micron-sized wires.
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What materials would be used?
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Would silicon nitride exposure to Rb tests need to be repeated (previously inconclusive)?
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How will the wire be tensioned and re-tensioned as temperature changes?
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Prototype needed for testing in Rb and at high temperature.
Action: Yes, perform a test. -
BPM compatibility:
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Can a BPM operate in a high-temperature environment?
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Is exposure to Rb acceptable?
Action: PM, MB, and MT to consult BPM experts. -
How many BPMs would be required?
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Action: Read the PRAB paper on spider-web measurements.
Known risks and mitigation:
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Wire handling difficulty → Consult PSI, hands-on trials
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Achieving 1 µm wire diameter → Consult PSI
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BPM operation in high temperature / Rb → Consult BPM experts
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Wire getting stuck → Test piece, ask BI about wire scanner issues
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Wire damage from beam energy deposition → Calculations
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Integration challenges → CAD studies
Beam Alignment Diagnostics (Injection Region)
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Action: MT to share downstream beam sizes (proton and 150 MeV electron) with GWA to determine screen positions.
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Screen choice: OTR, YAG, or Chromox?
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Will the laser beam also pass through the YAG screen?
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Consider two screens on a single plunger, angled at 90°.
Possibly unnecessary, as both electrons and protons reach the backside of the screen. -
Consider how and where to inject alignment He:Ne lasers.
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Mu-metal shielding in the injection region?
Action: PM and MT to perform calculations.
Laser Beam Dumps (Injection Region)
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A safety factor of 2 may not be required if no sensitive equipment is at risk.
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Action: Inspect previously used foils under a microscope.
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Should foils be moved by more than one beam spot size to avoid overlapping damage?
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Risks of alternative option (foil rotation)?
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Agreement: if the simpler solution works, it is preferable.
Injection Area Chamber
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Action: MT to re-check acceptable magnetic permeability with TE-MSC.
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Action: MT to check the material of the spectrometer vacuum chamber and whether it is available in sheet form.
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Consider adding electrical insulation (e.g. Kapton foil) between magnet poles and chamber.
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Does the chamber need to be anchored?
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Identify the pillar near the injection region (metrology).
Action: MT to confirm whether it is permanent and required.
Cabling
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GWA proposed TCC4 rack locations (assuming 24U racks).
Action: MT to propose to Fred and check for conflicts. -
Cable routing considerations:
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Cables will have a significant cross-sectional area.
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Cable paths should be as short as reasonably possible.
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Include overhead cable weirs connecting to trays at ~2.5 m height.
Schedule
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Cabling completion:
Tobias will try to schedule either Q4 2027 or Q1 2028.-
Action: Tobias to check with EN-EL whether cables can be used immediately after installation.
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Goal: install commissioning chamber and start commissioning as soon as cabling is ready.
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Switch to the final injection area once the 150 MeV e-beamline meets all beam specifications
(estimated time: ~2 months).-
First proton beam could be taken either in the commissioning chamber or the final chamber.
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Action: MT to send a summary of discussions to Tobias and comment on planning in EDMS.
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Tobias to provide updated planning by mid/end February.
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IR laser operation expected from 11/28.
Things to discuss:
For Tobias:
- Installation of supports for the plasma cell
- Cabling
- Installation of plasma source
- Commissioning of the plasma source with the temporary plasma chamber
- Uninstallation the temporary chamber
- Installation of the definitive plasma chamber
- Commissioning of the plasma cell with the definitive chamber
Again, is this correct and would you happen to know already how long each step is going to take?
OSR:
Calculations shared by Debdeep in email Mon 11/24/2025 3:59 PM
Magnets:
Vittorio: While for the 150 MeV line dipoles, PXMCXCAHWC, do you know if 100 mm is confirmed?
Chillers: CSCP Action à Patric and Marlene tell Fred the length they need for their rooms and where they want the door to be located. For now, the length shown in the model is 4m. Note that having a shorter-than-4m plasma diagnostics room will ensure that the Chillers can be placed close to the plasma cells (i.e. next to the plasma room in TSG4). The only other alternative to have an acceptable distance from chillers to plasma cells is to move (many) racks downstream (~2m per rack).
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