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Brief summary of run #8 (9 September)

Brief summary of run #8 (9 September). Shinji Machida o n behalf of the beam commissioning team ASTeC /STFC/RAL 14 September 2010. Aims. Find rf phase dependence of time of flight. Observe synchrotron oscillations. Time of flight (1) with rf waveform.

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Brief summary of run #8 (9 September)

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  1. Brief summary of run #8 (9 September) Shinji Machida on behalf of the beam commissioning team ASTeC/STFC/RAL 14 September 2010

  2. Aims • Find rf phase dependence of time of flight. • Observe synchrotron oscillations.

  3. Time of flight (1)with rf waveform • Compared with 1.3 GHz waveform, we can measure time of flight.

  4. Time of flight (2)14.5 and 18.5 MeV/c • Tof = 55.385 (1.3 GHz) x [1 – phi/(72 x 360)] • phi is phase shift per turn. 55.36 ns at 18.5 MeV/c 55.31 ns at 14.5 MeV/c

  5. Time of flight (3)comparison with model • It agrees with time of flight • by Zgoubi with field map (YoelGiboudot) • by Dynamical map with field map (YG) • but not by hardedge model. hardedge field map 18.5 MeV/c 14.5 MeV/c

  6. Time of flight (4)0.4 MV per turn in 18.5 MeV/c lattice • rf phase shift per turn is similar to previous results without rf voltage: ~18 deg/turn. • Different colors shows different global phase. • Revolution time is 55.385 ns (1.3 GHz) - 0.038 ns.

  7. Time of flight (5)phase relation • Relation between “Phase in page 5” and “Libera setting phase”. Phase in page 5 Phase in page 5 Libera setting phase weithout +66 offset Libera setting phase with +66 offset

  8. Time of flight (6)simulation • Phase oscillation can be simulated because now we know 1) revolution freq, 2) rf freq, and 3) assumption of slip factor. 20 turns 1.32 MV per turn 0.4 MV per turn

  9. Time of flight (7)experiment • Bunching (and debunching) is noticeable as in simulation. • 0 phase in simulation corresponds to ~180 deg in experiment. 1.32 MV per turn 1.0 MV per turn

  10. Time of flight (8)zero crossing phase 0 phase in simulation and ~180 in experiment corresponds here. (stable fixed point) Using relation on page 7, Libera phase and rf voltage are without +66 offset with +66 offset

  11. Time of flight (9)comparison • Oscillation in experiment with 1 MV and 1.32 MV looks similar to oscillation in simulation with 0.4 MV. • Bunching time • Capturing phase • This implies actual rf voltage is less than a half(!?). • Check individual phase again.

  12. Time of flight (10)next step • As long as rf freq is lower than rev freq, it is hard to see synch oscillation (or acceleration.) • A beam hit wall when it is accelerated. • rf cavities are retuned at 1.301 GHz, which is almost same as rev freq. • See deceleration phase of synch oscillation. • Measure oscillation frequency. • With lower momentum beam, try acceleration.

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