1 / 17

PAMELA lattice studies

PAMELA lattice studies. Dynamics of the Machida lattice. Outline. Linear lattice options Non-linear lattice options Machida lattice dynamics Future directions. Linear NS-FFAG lattices. Quadrupole & dipole elements e.g. KST (Keil, Sessler, Trobjevic) 48 cell lattice F/D doublet cells

luz
Télécharger la présentation

PAMELA lattice studies

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. PAMELA lattice studies Dynamics of the Machida lattice

  2. Outline • Linear lattice options • Non-linear lattice options • Machida lattice dynamics • Future directions PAMELA lattice studies – Dynamics of the Machida lattice

  3. Linear NS-FFAG lattices • Quadrupole & dipole elements • e.g. KST (Keil, Sessler, Trobjevic) 48 cell lattice • F/D doublet cells • Small orbit excursion • Large tune excursion • Resonance crossing E. Keil, A. M. Sessler, and D. Trbojevic. “Three ring FFAG complex for H+ and C6+ therapy” pg. 1681. EPAC Proceedings, 2006. PAMELA lattice studies – Dynamics of the Machida lattice

  4. Resonance crossing in linear lattices • Two significant factors: • Acceleration rate – need to cross quickly! • Number of cells • Number of machine resonances crossed • Ability to have long straight sections 21.6 19.2 Horiz. Cell tunes 16.8 Total tunes Vert. 14.4 12.0 9.6 7.2 4.8 2.4 Δp/p PAMELA lattice studies – Dynamics of the Machida lattice

  5. Resonance crossing with alignment errors • Simulated KST Ring 2 using ZGOUBI • Particles on closed orbit accelerated & tracked to extraction • Alignment errors (gaussian distributed) introduced • 20 error sizes, 10 lattices simulation for each • Amplification factor defined as: • Ax ~ 315 • (nb. Without acceleration COD 4.4) • 100μm error gives ~31.5mm orbit distortion! PAMELA lattice studies – Dynamics of the Machida lattice

  6. Emittance change through resonances • Real emittance change - crossing through integer resonance • E.g. isolated integer resonance • 36 macro particles on 5 π mm mrad emittance ellipse • 100 turns from KE=142 MeV Linear NS-FFAG(average Bn), T.Yokoi PAMELA lattice studies – Dynamics of the Machida lattice

  7. Avoidance strategies… • Cross resonances very quickly ? • Accelerate very quickly • RF voltage must be large • Pushing RF limits as it is… • Reduce number of resonances crossed ? • Reduce number of cells – fewer machine integer resonances • Reduce machine tune excursion to within an integer • i.e. reduce cell tune excursion to 1/N, where N is number of cells PAMELA lattice studies – Dynamics of the Machida lattice

  8. How to reduce tune excursion 1. Take NS-FFAG and add higher order components • Severely reduced dynamic aperture • Small dispersion makes chromatic correction hard OR 2. C.Johnstone – wedge shaped quadrupoles (see T.Yokoi’s talk) • edge focusing & path length of quads a function of momentum • effective focal length of lattice similar & independent of momentum • almost flat tune over the wide momentum range of factor 6 OR 3. S.Machida – different approach • Start from scaling FFAG with large k • Relax scaling law to get “non-scaling” PAMELA lattice studies – Dynamics of the Machida lattice

  9. Machida lattice: aim • Non-linear NS-FFAG (“tune stabilised”) • The aim: • Small orbit excursion • Few cells • Compact magnets • Small tune excursion • Long straight section for inj/extr. • Stability Diagram • Orbit excursion is inv. prop. to k (or dB/dr) • Take the largest possible k-value • For scaling – end of design procedure…? S. Machida, from PAMELA Design Review, June 08 PAMELA lattice studies – Dynamics of the Machida lattice

  10. Machida lattice: the idea • 8 Cell triplet FDF lattice • Approximate scaling r-k • Remove scaling law – only to decupole • Rectangular magnets (instead of wedge) • Magnets on straight line (easy alignment) • Long straight sections of over 2m • Orbit excursion < 30cm PAMELA lattice studies – Dynamics of the Machida lattice

  11. Machida lattice – ZGOUBI model • Total tune excursion within an integer Horiz. Vert. PAMELA lattice studies – Dynamics of the Machida lattice

  12. Dynamic Aperture • Simulations using ZGOUBI • (no fringe fields at present) • Close to 1/3 at extraction – can easily be shifted to achieve dynamic aperture D. Kelliher, from PAMELA Design Review, June 08 PAMELA lattice studies – Dynamics of the Machida lattice

  13. Alignment errors • ZGOUBI study with alignment errors (as before) • Ax ~ 1 (cf. 315 for linear lattice) • Expected – as no major resonances crossed! • Need to check with fringe fields PAMELA lattice studies – Dynamics of the Machida lattice

  14. Future directions • Understand resonance crossing • Include fringe fields in ZGOUBI for Machida lattice • Orbit/optics studies with errors • Optimise lattice PAMELA lattice studies – Dynamics of the Machida lattice

  15. Conclusions • Densely packed, linear lattices very sensitive to alignment errors when crossing resonances • Want sparse lattice, few cells, no resonance crossing • Machida lattice achieves this – though further studies needed! PAMELA lattice studies – Dynamics of the Machida lattice

  16. Questions? • Thanks for listening PAMELA lattice studies – Dynamics of the Machida lattice

  17. PAMELA lattice studies – Dynamics of the Machida lattice

More Related