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CAN WE KEEP THE CURRENT SYSTEM FOR LIU BEAMS ?

CAN WE KEEP THE CURRENT SYSTEM FOR LIU BEAMS ?. Francesco Cerutti , Alessio Mereghetti , Joao Saraiva. contributions from O. Aberle , J. Borburgh , N. Conan, K. Cornelis , L. Ducimetiere , B. Goddard, R . Losito , A. Masi , M. Meddahi , E. Veyrunes , H. Vincke.

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CAN WE KEEP THE CURRENT SYSTEM FOR LIU BEAMS ?

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  1. CAN WE KEEP THE CURRENT SYSTEM FOR LIU BEAMS ? Francesco Cerutti, AlessioMereghetti, Joao Saraiva contributions from O. Aberle, J. Borburgh, N. Conan, K. Cornelis, L. Ducimetiere, B. Goddard, R. Losito, A. Masi, M. Meddahi, E. Veyrunes, H. Vincke LIU-SPS Beam Scraping System Review 2013 Jan 22

  2. OUTLINE • reviewing the current scraping system • with regard to some (experienced and overcome) weaknesses • expectations from tracking – energy deposition coupled simulations • with regard to possible active material damage

  3. PRESENT SPS SCRAPERS • three pairs of H&V scrapers [essential for clean injection into the LHC]: • one in LSS5 (BSHV.51659), recuperated from ISR (early 1970s) • blade exchange in 2010, from 3cm copper to 1cm graphite (by reason of robustness) • currently spare of the spare

  4. LSS5 SCRAPER old assembly with risk ofcomponent failures significant increase of the local radiation levels (dose to machine and equipment, activation) impact of 2010 operation wrt 2009 and 2011

  5. LSS1 SCRAPERS [I] • two pairs in LSS1(BSHV.11759 and BSHV.11771), used since spring 2011 • 1cm graphite blades, new assembly • spare insignificant impact on the LSS1 radiation levels, more than two orders of magnitude higher than in LSS5 mainly because of the high energy dump [see numbers in the Helmut Vincke’s presentation]

  6. LSS1 SCRAPERS [II] Concerns: lifetime of edge-welded bellows, step motors challenged by fast movement However, mechanics/controls do not look as a critical limitation for the present system (spare could be produced and – timely, wrt to access RP constraints – installed) 2012 operation Jan 16, 2012 Jan 14, 2013 20k cycles in April 2012 to study the scrapers impact on LSS1 cables (dose measurements downstream cell 117, not pointing to a dramatic effect) 100k cycles

  7. SCRAPING MECHANISM 1cm 3cm z z 20 cm/s 0.008 sy/turn [actually at 3 cm/s] scraper (≡beam) movement implemented in FLUKA coupled to tracking code

  8. ICOSIM/SIXTRACK – FLUKA COUPLING Idea: to develop a two-in-one tool allowing the most accurate and efficient treatment both of beam transport (by the tracking code) and beam-matter interaction (by FLUKA), accounting for multiturn and moving devices, and preventing interface files and conflicting aperture models ICOSIM [by Hans Braun, up to sextupolesincluded] SixTrack[by Frank Schmidt] one tracking process and one FLUKA process take over each from the other at the geometry interfaces, communicating through a network port [by David Sinuela Pastor and VasilisVlachoudis]

  9. SCRAPER HEATING [I] vertical sweeping at 20cm/s (in reality 3cm/s) past ICOSIM-FLUKA simulation of nominal LHC injection Gaussian beam Q26 optics BSHV.51659 3.5um єn (similar beam size – not so crucial – at BSHV.11771 with Q20 optics and max LIU emittance) sy= 0.58mm 3.5 sx = 2.2mm 1cm 288 nominal (1.15E11) bunches 1.8 g/cm3 graphite

  10. SCRAPER HEATING [II] peak values for 288 nominal (1.15E11) bunches, 100um x 100um tranverse resolution

  11. INTENSITY LIMIT ROUGH GUESS adiabatic approximation (neglecting heat diffusion over 50um within several ten ms → pessimistic) thermomechanical analysis still to be carried out 0.22% scraped fraction 4.4% scraped fraction Copper limit 288 1.15E11 bunches

  12. SCRAPER HEATING [III] integral values for 288 nominal (1.15E11) bunches

  13. CLEANING DURATION 3000 turns ~ 75ms exp(-N2/2) for N=3.5 scraping at 3.5 sx

  14. LOSS PATTERN 1cm graphite blade illustrative (synchrotron motion not included here)

  15. CONCLUSIONS • recent (2012) operation experience demonstrated the current (LSS1) device reliability, for regular scraping of several % of a full (50ns spaced) train of ~1.5E11 proton bunches • induced radiation is not a real issue in LSS1 • blade heating represents on paper a concern to be more accurately studied especially in view of maximum LIU intensities (the new scraping concept offers some more margin in this respect, see the AlessioMereghetti’s presentation) • is a faster/more flexible system, as with dedicated bumpers and a fixed absorber, desirable from the operation point of view?

  16. BACKUP SLIDES

  17. IMPACT ON LSS1 CABLES Scrapers LSS1 : 31/08/2011 -> 03/11/2011 Scrapers LSS5 : 03/11/2011 -> 24/04/2012

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