Beam extraction - 50th anniversary of the CERN Proton Synchrotron

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– Quadrupoles (in SS29 and SS87) to raise Q h from 6.2 to 6.33, increase β h at the septa, and decrease the horizontal dispersion at the electrostatic septum and increase it at the first magnetic septum. – Sextupoles (one in SS7 and two in SS19) to provide the 19th harmonic defining the stable and unstable phase areas, and the zero harmonic to decrease the horizontal chromaticity |ξ h |. – One electrostatic septum in SS23 on the machine centre side (Fig. 11, left). – One magnetic septum in SS57 under vacuum on the machine centre side (the only magnetic septum under vacuum) (Fig. 11, right). – One magnetic septum in SS61 outside vacuum (Fig. 12, left). – Bumpers in SS19 and 27 to approach the electrostatic septum. – Bumpers in SS53, 59, 61 (septum type, Fig. 12, right) and 67 to approach the beam to both magnetic septa. D53 EXTRACTOR SEPTUM MAGNET 61 D59 FIRST SEPTUM MAGNET 57 D61 (septum) D67 D27 QUADRUPOLE 29 CERN PS SLOW EXTRACTION ELECTROSTATIC SEPTUM 23 QUADRUPOLE 87 D19 SEXTUPOLE 19 SEXTUPOLE 7 Fig. 10: Layout of the elements for SE61 10
Fig. 11: Left: electrostatic septum in SS23. Right: the thin septum in its tank. In 2007, the sextupoles in SS19 had to be displaced to free the straight section in conjunction with the installation of the multi-turn extraction (MTE). They were first placed in SS03 but it turned out that the separatrices were curved and that the efficiency was lowered and losses increased (parenthetically, the initial performance was restored by using octupole magnets to re-shape the separatrices at large amplitude). Nevertheless, to ease operation, it was decided to find a better place for the sextupoles, which were then moved again to SS01 and the efficiency returned to its previous value. Fig. 12: Left: the extraction septum in SS61. Right: the septum bumper in SS61. The phase plane plots at the electrostatic septum 23 (Fig. 13, left) and thin septum 57 (Fig. 13, right) show the main difference with the Square extraction. The improvement of the systematic losses on the first magnetic septum (thin septum) is obvious when the plots at the thin septa are compared (Fig. 9, right and Fig. 13, right). By a proper choice of the horizontal dispersion at the electrostatic septum and at the first magnetic septum, the separation between ejected and circulating beam was enlarged, the magnetic septum thickness could be enlarged, resulting in a welcome increase of its deflection angle. Therefore only one extractor magnet was needed and it could even be installed outside the vacuum enclosure. 11
Page 1 and 2: Beam extraction 1 Introduction In t
Page 3 and 4: high-quality cable used for the PFN
Page 5 and 6: 3.1 Integer resonance extraction 3.
Page 7 and 8: A last improvement came in 1971 wit
Page 9: the semi-quadrupole began to raise
Page 13 and 14: 3.3.3 Performance of the SE61 extra
Page 15 and 16: After the proposal, an experimental
Page 17 and 18: 80 70 60 β x β y D x SS31 50 40 S
Page 19 and 20: 3.3×10 13 protons per PS batch. Am
Page 21 and 22: Fig. 25: 3D view of the beamlets al
Page 23 and 24: Fig. 27: Sequence of beam profile d
Page 25 and 26: they were done over two consecutive
Page 27 and 28: Fast pulsed magnets (kickers), to b
Page 29 and 30: Fig. 34: Upper: Cross-section of th
Page 31 and 32: Fig. 36: Intensity of a MTE de-bunc
Page 33 and 34: [16] F. Galluccio, T. Risselada, Ch

Beam extraction - 50th anniversary of the CERN Proton Synchrotron

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