Discussion on single-turn excitation kickers for tune/optics/aperture measurement

Europe/Zurich
865/1-D17 (CERN)

865/1-D17

CERN

25
Show room on map

Discussion on single-turn excitation kickers for tune/optics/aperture measurement

27/02/2020

Present: Bren, Hannes, Thibaut, Nicolo, Reyes, Piotr, Christian, Verena, Gian Piero, Alex, Tom, Marek, Matt, Alvaro, Rogelio,...

LEIR

  • Draft LEIR FS defined, has baseline and option for upgrade. 4 mm kick amplitude and 192 ns rise/fall time with variable flat-top are adequate, improved performance with 8 mm and 135 ns.

  • Layout options to define (Nicolo, Reyes) and ABT to investigate basic configurations to meet kick requests in the specific locations (Alvaro, Bren, Thomas).

PSB

  • Draft PSB FS also defined, 5 mm at flat-top would be enough for 25 mm at injection to measure non-linearities.

  • Look at the real needed rise time with a realistic ‘optics’ bunch (Hannes, Piotr, GP).

  • Other techniques exist with kick response or AC Dipole (ACD) operation of TFB.

  • Check the amplitude of the correctors needed to get same linear optics measurement resolution (Piotr), and also the damper power needed for same resolution with ACD measurement (Piotr) – bearing in mind can measure 100x more turns with ACD, and can measure in orbit mode with kick response, with lower noise floor.

  • One major limit is 90 deg. phase advance. Would need more pick-ups…. important to quantify the difference in accuracy between 3 methods.

  • Look at possible use of PSB extraction kicker for H plane based on PS experience with KFA45, although expected to be complicated (Bren, Matt).

  • Agreed that 1 kicker per plane per ring is needed, but that no need for separate generators (if this is an advantage for ABT).

  • ABT to investigate basic configurations to meet kick requests in available locations (Alvaro, Bren, Thomas).

AD/ELENA

  • AD no chance to make turn by turn because of low bunch intensity.

  • ELENA can make turn by turn measurements with few 10ths of mm, used for correcting injection oscillations.

  • Optics measurements usually made with CO correctors, advantage to also measure at corrector location. This has also been used in SPS and LHC.

  • Added after the meeting: A side effect of efforts during the design of the ELENA pick-ups to use the sum signal for Schottky diagnostics is that the quality of the analog signal is good enough to obtain single pass precision of a few 10ths of a mm. This has been used to quantify and correct injection oscillations (analysing traces taken with OASIS). The digital electronics used and the FESA class do NOT provide turn-by-turn data.

PS

  • PS nice list of the techniques, use KFA45 for the H plane at all energies, tricky and maybe some MP considerations to evaluate.

  • Missing vertical excitation...propose to also draft requirements along lines of PSB/LEIR (Alex, Matt)

SPS

  • SPS have stronger MkQ kickers, check the kick amplitude available at 450 GeV (Bren, Hannes), optics not measured (yet) at top energy.

  • MKQ also very important for tune measurement at transition crossing etc., and for FT ions.

  • Also use chirp from the damper away from transition.

Discussion

  • Mis-use of inj/extract kickers for at least getting one plane – concerns on fall times and pulse length, and interlocking could be a general issue, deserves some discussion (Matt, Verena, Etienne)

Follow-up

  • Agreed another meeting next week same time

    • Basic parameters for PSB and LEIR kickers (Alvaro?)

    • Comparison of strengths needed for measurement techniques in PS (Piotr?)

    • PS needs for V plane (Alex?)

    • Interlocking concerns for mis-use of inj/extr kickers in LEIR/PS/PSB (Verena?)

    • Discussion

There are minutes attached to this event. Show them.