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TMCI threshold in 2007 and horizontal instability

TMCI threshold in 2007 and horizontal instability. September 18, 2007 B. Salvant. With the help of G. Arduini, R. Calaga, E. Métral, G. Rumolo, R. Tomas, G. Papotti. Agenda. Context Measurements MD on August 2 nd 2007 MD on August 27 th 2007 What to do next?. Context.

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TMCI threshold in 2007 and horizontal instability

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  1. TMCI threshold in 2007 and horizontal instability September 18, 2007 B. Salvant With the help of G. Arduini, R. Calaga, E. Métral, G. Rumolo, R. Tomas, G. Papotti

  2. Agenda • Context • Measurements • MD on August 2nd 2007 • MD on August 27th 2007 • What to do next?

  3. Context • Measurements revealed a longitudinal Impedance higher than expected for the SPS (E. Shaposhnikova APC 03/08/2007). • The SPS transverse impedance measurements do not show a significant increase (H. Burkhardt APC 17/08/2007). • A short MD on 27/08/2007 (G. Arduini et al) showed unstable behaviour in the horizontal plane. • Questions to be addressed: • Is the TMCI threshold the same as in 2006? • Can we give an explanation for this unstable behaviour in the horizontal plane?

  4. Agenda • Context • Measurements • MD on August 2nd 2007 • MD on August 27th 2007 • What to do next?

  5. MD on August, 2nd 2007 (1/2) • Participants : OP team, T. Bohl, R. Calaga, G. Papotti, G. Rumolo, B. Salvant, R. Tomas • Objectives : Can we see vertical modes shifting and coupling as beam current increases? Reproduce theoretical and simulation studies. Headtail Simulations

  6. MD on August, 2nd 2007 (2/2) • Settings : • Beam current [1 1010 1.3 1011]p/b • Low chromaticity in the vertical plane (-0.2-0.25), high chromaticity in the horizontal plane • RF Voltage very high at injection (3 MV instead of 700 kV in 2006) • Observation of the beam behaviour mainly with SPS Qmeter and Faraday Cage Transverse BPM after kicking in the vertical plane, about 900 ms after injection • Conclusion • Except for 30 minutes at the end of the MD, very different measurements and conditions than 2006 • Comparison is risky Measurements

  7. Agenda • Context • Measurements • MD on August 2nd 2007 • MD on August 27th 2007 • What to do next?

  8. MD on August, 27th 2007 (1/2) • Participants : OP team, G. Arduini, E. Benedetto, E. Métral (parasitic measurements) • Objectives : Compare TMCI threshold in 2007 with 2006. Measurements in 2003 (vertical)

  9. MD on August, 27th 2007 (2/2) Measurements in 2006 (vertical)

  10. MD on August, 27th 2007 (3/3) Measurements in 2007 (horizontal)

  11. MD on August, 27th 2007 (4/3) Measurements in 2007 (current)

  12. MD on August, 27th 2007 (5/3) Measurements in 2007 (BPM V) Measurements in 2007 (BPM H)

  13. MD on August, 27th 2007 (6/3) Measurements in 2007 (Sussix frequency analysis BPM H)

  14. Agenda • Context • Measurements • MD on August 2nd 2007 • MD on August 27th 2007 • What to do next?

  15. What to do next? • Not far enough in the analysis to conclude  massive amount of data to be analyzed and compared with previous years • However longitudinal motion affects the transverse motion • Instability in 2006 ?

  16. Longitudinal mode coupling simulated with headtail

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