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ICA Applied to Long Bunches

ICA Applied to Long Bunches. Jeff Kolski Informal workshop on ICS and High Intensity accelerators Indiana University Los Alamos Nation Laboratory 3/17/10 LA-UR 10-01611. Outline. A brief overview of LANSCE operations ICA applied to long bunches Single turn kick experiment

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ICA Applied to Long Bunches

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  1. ICA Applied to Long Bunches Jeff Kolski Informal workshop on ICS and High Intensity accelerators Indiana University Los Alamos Nation Laboratory 3/17/10 LA-UR 10-01611

  2. Outline • A brief overview of LANSCE operations • ICA applied to long bunches • Single turn kick experiment • Some interesting ICA modes

  3. Los Alamos Neutron Science Center (LANSCE)

  4. Los Alamos Neutron Science Center (LANSCE) Ultra Cold Neutrons (UCN) Proton Radiography (pRad) Ion Sources Sector J Isotope Production Facility (IPF) Switch Yard (SY) Area A TransitionRegion (TR) Central Control Room (CCR) Coupled Cavity Linac (CCL) (805 MHz) Drift Tube Linac (DTL) (201 MHz) Jeff’s Office Building 6 Lujan Center Proton Storage Ring (PSR) Weapons Nuclear Research (WNR) Google Maps

  5. Proton Storage Ring (PSR) Circumference = 90m Beam energy = 798 MeV Revolution frequency =2.8 MHz Bunch length = 290 ns (73 m) Accumulation time = 625 μs = 1746 turns Pinger WM41 and WC41 ES41y RF Buncher ES43q RJM

  6. Ring Parameters Circumference C 90.2 m Beam Kinetic Energy T 798 MeV Betatron Tunes νx, νy 3.19, 2.19 Transition γγt 3.1 Phase Slip Factor η -.19 Max rf Voltage Vrf 18KV Buncher Harmonic, Freq h, f 1, 2.795 MHz Synchrotron Tune (10KV) νs .00042 Mean Pipe Radius b .05 m

  7. Linac frequency 201.25 MHz, 5 ns Injection Scheme Turn 1 Turn 2 Turn 3 Turn 14 Turn 15 PSR frequency 2.8 MHz, 358 ns 72.07 of the Linac frequency

  8. Instead of having several BPMs distributed around a ring, use one digitized BPM signal where each digitization bin is a time slice along the length of the beam. • For ICA, the time slices are effectively BPMs along the beam length. • The resulting spatial modes then describe the strength of the motion along the beam. ICA for long bunches

  9. Setup for theSingle Turn Kick Experiment • Data taken by R. Macek in Oct. 2006. • Accumulate for 1225μs • Store for 200 μs • Give the beam a single turn kick ~400 turns before extraction to induce coherent betatron motion. • Capture digitized BPM data using wc41 and wm41 (vertical sum (vs) and difference (vd), horizontal sum and difference).

  10. … And begins the Fishing Expedition • ICA of the vd signal from wm41 yields modes containing transverse information. (coherent tune shift) • ICA using the vs signal from wm41 yields modes containing transverse and longitudinal information. (transverse coherent tune shift, longitudinal motion, and injection structure). • ICA of wc41 yields the same modes as using wm41vs except with a low frequency bias.

  11. A Betatron mode • Mode only appears after the transverse kick. • Temporal part of mode FFT peaks at twice the tune.

  12. ICA and Coherent TuneShift • Several ICA modes describe the coherent tune shift. • In this example, there are only three double modes. • In principle there is an ICA tune mode for each the time slice. • ICA yields the modes that most diagonalize the time-lag covariance matrices

  13. Another Betatron mode • Strongest betatron modes show double FFT peak. • Could transverse profile be non-symetric?

  14. A “Noise” Mode • DC temporal mode without much frequency • The SV from the time lag correlations are very small.

  15. “Scope” mode • Temporal mode is DC • Spatial mode even where beam is not. • Mode FFT peak ~ the scope clock.

  16. The “Injection” Mode • Mode only appears during injection. • Mode FFT peaks at 72.07 (the injection sub-harmonic PSR). • 54 peaks in the spatial mode, same number as the injected micropulses per turn.

  17. CombiningInjection Modes

  18. Late Injection? • are

  19. A Longitudinal Mode • Shoulder on the front of the cumsum of the spatial mode. • If beam was injected late, does this mode describe the motion of the beam filling the front of the bucket?

  20. Another Longitudinal Mode Delay between the cumsum of the spatial mode and the beam current. Another example of injecting late?

  21. Last Longitudinal Mode • Spatial modes has three humps. • Peaks at the synchro-nous phase and ± 90°.

  22. Continuing Work • Experimentally verify the ICA modes • Understand how the number of turns, modes, time lags, and BPMs effect the ICA. • Simple simulations

  23. Acknowledgements • A special thanks to • SY Lee and Xiaoying Pang (Indiana University) • Bob Macek and Rod McCrady (LANL)

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