1

CAN WE KEEP THE CURRENT SYSTEM

FOR LIU BEAMS ?Francesco Cerutti,

Alessio Mereghetti, Joao Saraiva

LIU-SPS Beam Scraping System Review

2013 Jan 22

contributions from O. Aberle, J. Borburgh, N. Conan, K. Cornelis, L.

Ducimetiere, B. Goddard, R. Losito, A. Masi, M. Meddahi, E. Veyrunes,

H. Vincke

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 2

• reviewing the current scraping systemwith regard to some (experienced and overcome) weaknesses

• expectations from tracking – energy deposition coupled simulationswith regard to possible active material damage

OUTLINE

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 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

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 4

LSS5 SCRAPERold assembly with risk of component failures

significant increase of the local radiation levels (dose to machine and equipment, activation)

impact of 2010 operationwrt 2009

and 2011

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 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]

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 6

LSS1 SCRAPERS [II]

Concerns: lifetime of edge-welded bellows, step motors challenged by fast movementHowever, 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 operationJan 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

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 7

SCRAPING MECHANISM

1cm3cm

20 cm/s

0.008 sy/turn

z

z

scraper (≡beam) movement implemented in FLUKA coupled to tracking code

[actually at 3 cm/s]

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 8

ICOSIM/SIXTRACK – FLUKA COUPLING

ICOSIM [by Hans Braun, up to sextupoles included]

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

SixTrack [by Frank Schmidt]

one tracking process and one FLUKA processtake over each from the other

at the geometry interfaces,communicating through a network port

[by David Sinuela Pastor and Vasilis Vlachoudis]

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 9

SCRAPER HEATING [I]

1cm

3.5 sx =

2.2mm

288 nominal (1.15E11) bunches

vertical sweeping at 20cm/s (in reality 3cm/s)

1.8 g/cm3 graphite

sy = 0.58mm

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.11771with Q20 optics and max LIU emittance)

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 10

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

resolution

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 11

INTENSITY LIMIT ROUGH GUESS

288 1.15E11 bunches

adiabatic approximation (neglecting heat diffusion over 50um within several ten ms → pessimistic)thermomechanical analysis still to be carried out

4.4%scraped fraction

0.22%scraped fraction

Copper limit

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 12

SCRAPER HEATING [III]

integral values for 288 nominal (1.15E11) bunches

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 13

CLEANING DURATION

exp(-N2/2)for N=3.5

3000 turns ~ 75ms

scraping at 3.5 sx

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 14

LOSS PATTERN1cm graphite

blade

illustrative(synchrotron motion not included here)

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 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 Alessio Mereghetti’s presentation)

• is a faster/more flexible system, as with dedicated bumpers and a fixed absorber, desirable from the operation point of view?

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 16

BACKUP SLIDES

2013 January 22 F. Cerutti LIU-SPS Beam Scraping System Review 17

IMPACT ON LSS1 CABLES

Scrapers LSS1 : 31/08/2011 -> 03/11/2011Scrapers LSS5 : 03/11/2011 -> 24/04/2012