1 / 18

Advanced Magnet Technologies for High-Performance LHC Crab Cavities Workshop

This workshop, held at CERN on December 15, 2010, focused on the latest advancements in magnet technologies, particularly separation dipoles and quadrupoles, essential for achieving high-performance crab cavities in the LHC. Key discussions included the limitations of current Nb-Ti technology and the potential of Nb3Sn magnets to enhance field strength. Attendees explored strategies for optimizing aperture sizes, enhancing magnetic fields, and mitigating radiation effects on magnet design. Contributions from experts were acknowledged, emphasizing collaborative efforts in furthering accelerator technology.

gayle
Télécharger la présentation

Advanced Magnet Technologies for High-Performance LHC Crab Cavities Workshop

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CERN, 15th December 2010 4th LHC Crab cavity workshop VERY LARGE CROSSING ANGLES AND MAGNET TECHNOLOGY E. Todesco CERN, Geneva Switzerland Acknowledgements: R. De Maria, R. Tomas, F. Zimmermann

  2. CONTENTS • Dipoles • Quadrupoles

  3. SEPARATION DIPOLES • In the present LHC lay out the separation dipoles are not at the limit of Nb-Ti technology • D1 IP1 and IP5: resistive magnets • Single aperture • Field ~1.3 T • Length: 6*3.4 m ~20 m • Kick: ~26 T m • D1 IP2 and IP8: RHIC-like sc magnets • Single aperture 80 mm • Field ~3.8 T • Length: ~9.5 m • Kick: ~36 T m Resistive D1 cross-section Superconducting D1 cross-section

  4. SEPARATION DIPOLES • In the present LHC lay out the separation dipoles are not at the limit of Nb-Ti technology • D2: RHIC-like sc magnets • Double aperture 80 mm • Field ~3.8 T • Length: ~9.5 m • Kick: ~36 T m • D3 • Double magnet 80 mm • ~3.8 T ~9.5 m ~36 T m • D4 • Double aperture 80 mm • ~3.8 T ~9.5 m ~36 T m Superconducting D2 cross-section Superconducting D4 cross-section Superconducting D3 cross-section

  5. SEPARATION DIPOLES • What one wants • Larger aperture • More compact, larger kick  higher field • Relation aperture-field-beam separation for two-in-one magnets • Margin: if these magnets work in a place with radiation, more margin may be needed • 33% instead of the usual 20% we have in cell magnets

  6. SEPARATION DIPOLES • Aperture - Field • In a dipole aperture comes without losing much field – you just have to pay for the cable … • 30 mm coil thick (as in the LHC dipoles) gives ~10 T short sample • 6.5 T with 33% margin is a reasonable operational field • This would reduce length of resistive D1 from 20 to 3.5 m and D2-D4 from 10 to 5.5 m Short samplefield vs aperture and differentcoilthickness for Nb-Ti dipoleat 1.9 K

  7. SEPARATION DIPOLES • Aperture – Field – beam separation • For a two-in-one magnet there is a minimal distance between apertures • D2: minimal distance ~ aperture+2*coil thickness+2*40 mm • One could easily reduce to 2* 30 mm the distance between coils 80 mm Minimum separation vs aperture and differentcoilthickness for a 60 mm distance betweencoils

  8. SEPARATION DIPOLES • More exotic designs • Open midplane dipoles [R. Gupta et al.] • To cope with places with large radiation • Relies on the idea of placing coils where Lorentz forces are not pushing • Less effective in terms of field-coil width • Mechanical structure to be analysed • Very fascinating, still on paper • Good field quality can be achieved • Coil-free midplane[J. Bruer, E. Todesco, IEEE Trans. Appl. Supercond. (2009)] • The midplane is not open, but there is no coil • Less effective in terms of field-coil width • Mechanically viable • Good field quality can be achieved Conceptual design of open midplanedipole Coil lay-out in a coil-free midplanedipole

  9. SEPARATION DIPOLES • There are two positions in the community • Exploring open midplane to get rid of radiation • Shielding in not enough effective! • Make the dipole larger and shield it • A standard design with larger aperture requires less conductor than an open midplane! • What about Nb3Sn? • It can give about 50% more field, i.e. reaching the 15 T short sample • Gives more temperature margin • Is more expensive • Is more strain sensitive, even though latest results show good performance up to 200 MPa[M. Bajko, S. Caspi, H. Felice, et al. TQ test at CERN]

  10. CONTENTS • Dipoles • Quadrupoles

  11. IR QUADRUPOLES • In the present LHC lay out the IP quadrupoles ARE at the limit of Nb-Ti technology • MQXA-B • Single aperture 70 mm • Gradient ~220 T/m at 1.9 K • Length: ~5.5 – 6.3 m • MQY • Double aperture 70 mm • Gradient ~160 T/m at 4.2 K MQXA cross-section MQXB cross-section MQY cross-section MQY assembly

  12. IR QUADRUPOLES • What one wants • Larger aperture • More compact, larger gradient  higher field • Relation aperture-field-beam separation for two-in-one magnets • Margin: is it enough the 20% taken in the LHC ? • We already reached the limit with Nb-Ti • Either we explore new ways in the optics satisfying the gradient-aperture-separation requirement[S. Fartoukh, sLHC-PROJECT-Report-0049 (2010)] • Or we use Nb3Sn – 50% larger gradient for the same aperture • Or we couple both things …

  13. IR QUADRUPOLES • Aperture - Gradient • In a quadrupole aperture is very expensive • At zero order gradient is inversely proportional to aperture • 30 mm coil thickness in 70 mm aperture (as in the LHC IR quads) provide about 250 T/m short sample • Adding more coil does not help Short sample gradient vs aperture and differentcoilthickness for Nb-Ti quadrupoleat 1.9 K

  14. IR QUADRUPOLES • Aperture – Field – beam separation • For a two-in-one magnet there is a minimal distance between apertures • Minimal distance ~ aperture+2*coil thickness+2*25 mm • 50 mm is what we have in MQY – difficult to make better but … Minimum separation vs aperture and differentcoilthickness for a 50 mm distance betweencoils

  15. IR QUADRUPOLES • Asymmetric coil designs [V. Kashikin, EPAC 2006] • Allows to further reduce the distance between apertures to nearly zero • 100 mm aperture, with ~40 mm coil thickness • The cross-talk is compensated via the coil cross-section • Looks viable from a practical point of view Coillayoutproposed to reduce the beamseparation[V. Kashikin]

  16. IR QUADRUPOLES • Aperture – Field – beam separation • With the asymmetric coil we could reduce to • Minimal distance ~ aperture+2*coil thickness+2*10 mm Minimum separation vs aperture and differentcoilthickness for a 20 mm distance betweencoils

  17. LARGE CROSSING ANGLE LAY OUT • 8 mrad crossing angle • First quadrupole at 23 m • Beam separation starts at ~200 mm • With 200 T/m and 63 mm aperture the quadrupole is viable • But one is at the limit, one cannot go much lower: 150 mm – 6 mrad with the same apertures • Quadrupole coils would be non-parallel within the common iron yoke this has never been done but looks viable 8 mradcrossing angle scheme[R. Tomas et al, Lumi 06]

  18. CONCLUSIONS • LHC is at the limit for Nb-Ti technology for IR quadrupoles, and well below for separation dipoles • Much room for improving dipoles staying with Nb-Ti – both for quads and for dipoles Nb3Sn gives 50% more • We sketched the mail relations • Aperture - field - beam separation (dipoles) • Aperture - gradient - beam separation (quadrupoles) • Several ideas have been proposed – but are still on paper • Open midplane to deal with radiation • Asymmetric coils to decrease beam separation • The 8 mrad scheme is not far from the limit • 6 mrad could be possible • Below it, one should change the optics

More Related