Superconducting Solenoid-Based Focusing Lenses for HINS Linac I. - - PowerPoint PPT Presentation

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Superconducting Solenoid-Based Focusing Lenses for HINS Linac I. - - PowerPoint PPT Presentation

Feb 04, 2024 261 likes •489 views

Superconducting Solenoid-Based Focusing Lenses for HINS Linac I. Terechkine AAC Meeting November 16-17, 2009 Outline Basics of solenoid focusing, requirements, and R&D structure RT section lens S/C sections lenses

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SLIDE 1

Superconducting Solenoid-Based Focusing Lenses for HINS Linac

  • I. Terechkine

AAC Meeting November 16-17, 2009

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SLIDE 2

Outline

  • Basics of solenoid focusing, requirements,

and R&D structure

  • RT section lens
  • S/C sections lenses
  • Cryomodule design approach
  • Summary

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Why Solenoid Lens?

  • One focusing element provides axially

symmetric focusing – important for high intensity beams.

  • The beam loss is governed by emittance growth

and halo formation due to non-linear effects in the low energy sections ( β << 1 ), where Coulomb forces are strong. Solenoids provide smooth axially symmetric focusing that helps to limit emittance growth.

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SLIDE 4

How it works

  • 1. Radial component of a fringe field

combined with asymmetric particle rotation provides radial component of the particle velocity;

  • 2. Rotation in the longitudinal field

results in different azimuthal position

  • f the particles after the lens.

eff c eff c R

L B eV T q m L B c q m v c R f

2 2 2 2 2 2

) ( 8 1 4 ⋅ ⋅ = ⋅ = ⋅ = β β Focusing length:

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SLIDE 5

Requirements

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SLIDE 6

Project Structure

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SLIDE 7

RT Section Lens

RT CH Section M E B T Cryogenic Line Chopper RT CH Cavities (16) Solenoids (19)

2 . 5 M e V 10 MeV

Buncher Cavities (2)

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SLIDE 8

Lens Design

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HTS leads. Helium line. Vacuum relief. Instrumentation / access port. Support post. Thermal shield (80K). Power lead 80K anchor. LN2 line for shield and HTS leads. Solenoid magnet with helium vessel. Conduction cooled copper lead. Removable lead cover. 18 inch (457 mm) diameter vessel.

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SLIDE 9

Lens Fabrication

Corrector Assembly

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Lens Performance

CH SOLENOID PRODUCTION STATUS: 13 Type-1 (without Steering Dipoles): 11 tested 10 Type-2 (with Steering Dipoles): 9 tested Quality Assurance Re-testing at Fermilab First 4, then 1 of every 4: 4 T2, 3 T1 done; two tests pending Type-1 Type-2

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SLIDE 11

Lens Testing

MTF: Stand-3 MTF: Stand-6

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SLIDE 12

Superconducting Section Lenses

  • Cold bore design
  • Corrector field quality
  • 10-5 T fringe field
  • Alignment issues

Pre-Production SS1-T2 Solenoid Quench Performance 150 170 190 210 230 250 270 290 5 5.5 6 6.5 7 7.5 8 B (T) I (A)

MC BC B-973 8277-2A2B

I = 190 A

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SLIDE 13

Dipole Corrector

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SLIDE 14

Fringe Field Test

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Focusing field at solenoid center: 5 T @ 160 A Requirement for field at cavity surface: <10 µT @ 225 mm Testing new shielding material from Amuneal

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SLIDE 15

Fringe Field Test

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Alignment Requirements

  • Alignment requirement: +/-150 µm (with dipole

correctors (B*L ~ 0.5 T-cm) and sensitive BPM)

  • Cryogenic environment: vacuum + low temperature
  • Must allow reproducible assembly on an insertion

bench (clean room) and in the cryomodule

  • Must allow reliable measurements on the beam line

Promising approach – optical alignment scheme

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SLIDE 17

Optical Alignment

Camera Camera Beam Splitter with Partial Mirror Partial Retroreflector Cryostat Window Cyrostat Window Laser Pressure Vessel Solenoid

CCD Camera: 1 µm resolution Corner Reflector

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SLIDE 18

Alignment R&D

  • Proof-of-principle test has been made – OK
  • Alignment scheme bench test in preparation
  • Test cryostat for SS-1 lens certification and for

the alignment concept verification by comparison with other alignment methods

  • Prototype cryomodule with RF cavities to

finalize assembly and alignment procedure. Testing with beam.

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SLIDE 19

Test Cryostat Concept

  • Existing cavity test cryostat

design

  • Warm bore to allow stretched

wire technique

  • Laser-based alignment system
  • Modified position of the current

lead assembly

  • Prototypes cryomodule design

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Conclusion

  • Designs of all focusing lenses for the HINS linac have been

completed (including ones with embedded dipole correctors); test methods have been developed; lens performance is well understood.

  • Room temperature section lenses are in the final production

stage; embedded BPM feature is being implemented.

  • Lenses for superconducting cavity section are in the final

prototyping stage (test of a pre-production lens is ongoing).

  • Developed fringe field measurement method can be used to

verify shielding efficiency in any RF cryomodule.

  • Suggested alignment method is beneficial for any linear

superconducting accelerator.

  • Testing solenoid-based transport channel is of general

importance for accelerator physics.

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SLIDE 21

Acknowledgments Participant List:

  • G. Davis, C. Hess, F. Lewis, S. Sanchez,
  • T. Wokas, Y. Huang, D. Orris, T. Page,
  • R. Rabehl, W. Schappert, D. Sergatskov,
  • M. Tartaglia, I. Terechkine, J. Tompkins.

Support from departments: D&D, Q&M, T&I, MS, and SRF. Publication list – 52 inputs

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