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First results of BBA tests at FERMI @ Elettra (Trieste) and Update from ATF2

First results of BBA tests at FERMI @ Elettra (Trieste) and Update from ATF2. Andrea Latina for the CLIC Beam Physics team Inputs on ATF2 from Juergen Pfingstner and Marcin Patecki CLIC Project Meeting – June 13, 2014. Introduction / Disclaimer.

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First results of BBA tests at FERMI @ Elettra (Trieste) and Update from ATF2

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  1. First results of BBA testsat FERMI @ Elettra (Trieste)and Update from ATF2 Andrea Latina for the CLIC Beam Physics team Inputs on ATF2 from JuergenPfingstner and MarcinPatecki CLIC Project Meeting – June 13, 2014

  2. Introduction / Disclaimer • We tested our BBA tools developed for FACET at Fermi, Elettra, Trieste • Due to some bugs in the software interfacing our tools with their control system, we ended up having only three hours of effective beamtime

  3. Fermi @ ElettraFree Electron Laser for Multidisciplinary Investigations

  4. FERMI electron beamlines Single-pass FEL w/ 10 Hz repetition rate Linac energy: from 100 MeV to ~1.2 GeV Bunch charge: 800 pC Bunch length: from 1.5 mm to 60 micron Emittance at gun: ~1.2 mm mrad

  5. The Fermi control room

  6. BBA setup and System Identification Measured horizontal orbit response matrix The goal was to test our automatic steering tools: • Orbit + Dispersion + Wakefieldcorrection(1:1 + DFS + WFS) BBA Setup: • 27 X correctors • 27 Y correctors • 30 BPMs Machine: • 1.5 betatron oscillations • Effective bpm resolution = 5 - 10 micron • Single-bunch 10 Hz repetition rate • SysID time required: • About 3 minutes to measure 1 response matrix (can be reduced to 30 seconds, with deeper integration in their control system)

  7. Dispersion-Free Steering The dispersion was measured reducing the amplitude of klystron 2 to 98% of its nominal value This operation occurs in 1 cycle @ 10 Hz Weight for DFS = 7 (tuned for ~10 micron BPM resolution)

  8. Dispersion measurement before DFS 200 mm 800 mm

  9. Dispersion measurement after DFS 50 mm 25 mm Vertical dispersion reduced by a factor ~40 ! Horizontal dispersion by factor ~4 (!)

  10. Emittance before BBAat the end of L4 H V

  11. Emittance measurement after DFS Horizontal emittance from 4.31 mm mrad to 3.30 mm mrad. Vertical emittance wasn’t good though: needs investigation.

  12. 1:1 + WFS The wakefields were measured by changing the bunch charge to 650 pC (tests with 900 pC were foreseen, but there was not time for performing them) Changing the charge takes about 10 seconds (time for charge feedback to converge) Weight for WFS = 7 - 20 (tuned for ~10 micron BPM resolution)

  13. 1:1 + DFS + WFS

  14. Emittance measurement after1:1 + DFS +WFS H V • Emittancesummary at Linac End: (H; V)(measurement error: ~±0.05 mm mrad) • Before correction: (4.31; 3.21) mm mrad • After DFS: (3.30; - )mm mrad • After DFS+WFS: (2.75; 2.57) mm mrad (-35% in X, -20% in Y)

  15. J. Pfingstner & M. Patecki Ground motion correlation experiment at ATF2 • Goal 1: Show that the beam motion (due to ground motion) can be predicted via motion sensors (correlation between two measurements). • Goal 2: Correct the beam motion via a feed-forward system. • Purpose: Such a feed-forward system could simplify and improve the ground motion mitigation for ATF2 and for linear colliders in general. • Experimental setup for goal 1: • Acquisition of • BPM readings • Acquisition of • GM readings • Beam arrival signal

  16. Region with strong ground motion source At least two were problems identified Water pipes under girder (probably touching at one point) Heavy objects on the girder (lead bricks, Dipole magnet). This could lower resonance frequency. Q2X Cooling water pipes Q1X J. Pfingstner & M. Patecki

  17. Orbit jitter reduction after detecting excitation sources Correlation Beam jitter • The correlation between motion sensors and BPM measurements have been up to 70%. • Strong excitation of quadrupole motion was detected via motion sensors. • An inspection showed that water cooling pipes and tubes were touching the girder. • After removing the excitation, orbit jitter was reduced from 20% to 14% (half the power). • Similar excitation detected and removed further upstream. Later measurements revealed the existence of another jitter source. This has to be investigated. J. Pfingstner & M. Patecki

  18. Conclusions / Future Plans I. Beam-based alignment tests • Fermi is a very good machine for tests • Very fast control system • Excellent diagnostics • Our tools worked very well: emittance reduced by ~35% in H and ~20% in V • Future plans: near future • Study convergence and fully explore the space of parameters • Envisage tests of tuning bumps? on-line parasitic DFS / WFS? II. Ground-motion correlation experiment at ATF2: • Important progress: • One jitter source located and removed: orbitjitter was reduced from 20% to 14% (half the power) • Correlation measurements improved as well • Future plans: • Search for the remaining jitter sources, by putting the sensors to further locations • Start preparing for goal 2 (uncertain time scale) III. Other tests: FACET, Wakefields in the accelerating structures, …

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