CERN Accelerating science

Pre Injection Plateau

Standard procedure to be followed after a scheduled beam dump and cycle down of all magnets. This stage to prepare machine to take pilot. See also injection request.

Use Case:

• 1 ring setup, 
• 2 ring setup,
• Injection for physics, 
• MD & variations
• beam abort in ramp, power abort in ramp, quench...

Outline

1. LHC ramp down to Front porch (functions where applicable)
2. Issue pre-injection warning to the injectors
3. Following front porch activities
4. Load PLP to power converters
5. Synchronous ramp to injection level - want all main circuits to arrive at exactly the same time - coherent persistent current decay.

Sequence

Ramp down to ~ 600 A. [Drive] Check that power converters have performed cycle down properly. [Check]
Set power converter PLEP parameters e.g. S REF PLEP,6000,2.6,6.96 final current 6000A, 2 A.s-2, 6.96 A.s-1
Collimators out  [Settings][Drive] [Check]
TDI to parking  [Settings][Drive][Check]
TDCQ out  [Settings][Drive][Check]
Kickers to standby [State][Drive]
Dumps - active  [Read State][Read Parameters][Check]
Check kicker timing [Read Parameters][Settings][Check]
Check BST. 
RF: 400 MHz & transverse dampers:

• Set RF frequency to injection level [Settings][Drive]
• Set the gain of the phase loop amplifier [Settings][Drive]
• Set the gain and time constant of the synchronization loop amplifier, [Settings][Drive]
• Close the phase loop around the VCO [State][Drive]
• Switch the RF DRIVE ON, Switch the phase loop to the cavity sum signal [State][Drive]
• Reset the revolution frequency generator - see RF [State][Drive]

BI: check that BI front-ends are pre-configured with [Settings] relevant to the foreseen beams.

Check: interlock system operational
Check BLMs
Check: magnet protection system
Check: beam and power abort system operational.
Power converters: check state & tolerances

QBT: test spikes at 90 GeV

Possible checks following quench (separate use case).

• Tests afer high current quench
• Tests after low current quench
• DFB quench tests, check lead temperatures

FiDeL: produce prediction of persistent current based on powering history, incorporate into settings

SPS - Check synchronization between LHC, SPS and PS. Foresee training sequence in SPS for a pulse or two on the LHC cycle, during this time synchronization can be established.

Transfer lines - Pilots to TEDs, check converters, instrumentation, steering etc.

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