TRICKLE INJECTION

1
TRICKLE INJECTION

• Injected Beam Orbit Control Improvement
• New Kicker Power Supplies
• Injection Tuning
• Injection Problems
• Ideas
• Thanks to R. Iverson (incoming beam stability),
  A. Kulikov (injection kicker upgrades), and F.J.
  Decker with Operations for doing all the work.

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Injected Beam Orbit Control Improvement

• Orbit in High Energy Injection line is now
  monitored by unmultiplexed Beam Position Monitors
  leading to faster more operable position
  feedback.

3
HER Injection Match Area Orbit Feedback
4
Injection Kicker Upgrades
Summer 2004 power supplies, diagnostics, and
controls were redone. Result is one power supply
per magnet so we have independent amplitude and
timing controls of the two kickers in each ring,
with many excellent diagnostics.
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Injection Kicker Diagnostics

• Kicker diagnostic was used to diagnose problem
  with Bunch Intensity Control system where only
  bucket 4 was getting beam.

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Injection Kicker Timing
Timing stable to /- 1.5 ns
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LER Kicker Timing Adjustment
Intentional adjustment of 0.2 volts on the
thyratron reservoir of the second LER injection
kicker (bottom) and the resulting time change of
about -10 ns (top).
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LER Injection Kicker Timing difference
Difference of the timing of the two injection
kickers in LER. Change at about 5 December is
intentional. Kicker Amplitudes and pulse lengths
are also adjusted. (Betatron phase is the other
parameter which is adjusted.)
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Trickle Tuning Setup

• Setup standard ring injection using first turn
  orbits, septum screens, etc. (the Uli procedure)
• Setup position feedbacks
• Monitor with BABAR diagnostics shown at previous
  MACs (and new SVT single shot radiation monitor).
• Setup quanta (4 desired various incoming
  intensities) correctly and execute a detailed
  procedure to get incoming intensities matched in
  energy and phase with minimum energy spread.
• Set up the energy feedbacks.
• Tune for minimum jitter.
• Raise bunch currents and tune septa bumps,
  position launch, and tunes.

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Position in the Septum

• Position of the stored and injected beams is for
  minimum separation between stored and injected
  bunches. Position (and angle) of the stored beam
  in the septum is chosen for best injection
  efficiency, backgrounds, and luminosity. Lifetime
  usually is reduced in favor of these other
  parameters.
• Ramifications With beam-size changes (due to
  change in beam-beam or other factors) septum
  bumps must be tuned. At higher bunch currents,
  there is significant loss of stored beam leading
  (in typically the LER) to a trade off between
  efficiency and backgrounds. So, in strong
  beam-beam, standard injection setup doesn't apply.

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Trickle Injection Problems

• Incoming beam phase and energy drift are not well
  compensated by feedbacks and continuous operator
  tuning is necessary.
• Energy feedback for extraction from Linac This
  feedback uses high power phase shifters and gain
  is not linear. If energy of the beam before the
  feedback changes significantly, then the feedback
  coefficients require re-setup. This typically
  leads to the less often used quanta to be
  mis-tuned in either energy or energy spread.
• No feedbacks read and control independently on
  all quanta, so those who don't read all quanta
  don't function during trickle.
• Damping Ring RF stability jitter. The RF systems
  were not designed for running high and low
  intensities simultaneously (tuners cant jump
  back and forth in milliseconds). Resultant tuning
  of the RF is therefore a compromise between
  intensities and usually set to favor the higher
  intensities.

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Trickle Injection Problems contd.

• Positron quanta adjustment method creates wide
  energy spread and beam loss before the damping
  ring leading to radiation damage of components.
• Communication to BABAR. Trickle triggers not sent
  if micro PR02 is down. (redundant triggers from
  PR00 should cure this)
• 15ms fliers in HER these went away by changing
  the HER ring energy by a small amount and we
  don't know why.

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Ideas

• Klystron timing based Energy feedbacks
• Find new pulse to pulse control of positron
  intensity (other than loss by misphasing RF)
• Build new feedbacks to control on all quanta
• Study why stored beam position in Septum talks to
  luminosity.

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Additional Backup Topics
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Optics changes between kickers

• Phase advance between kickers was re-adjusted
  after the new degrees of freedom were added.