1. RF and Sequences Andy Butterworth BE/RF
Thanks to V. Kain, D. Jacquet, R. Alemany, M. Lamont, P. Baudrenghien

2. Outline System overview Equipment control and sequencing Functions
Actions through LHC cycle
Conclusion

3. LHC 400 MHz (ACS) RF system Power system Low Level
1 klystron per cavity
1 power converter serves 4 klystrons (1 cryomodule)
Cavity controller: feedback loops to control phase and amplitude in the cavity
reduce the cavity impedance by factor 100
very fast: RF feedback loop delay ~ 600 ns
Beam control: loops around the beam (phase, radial & synchro loops), frequency program
slow: updates once per turn (11 kHz)
RF synchronization: between rings, and bunch-into-bucket transfers from SPS
Low Level
Cavity Controller (2 VME crates): RF control loops around cavity/klystron
Beam Control (5 VME crates): phase, synchro, radial loops around beam
RF Synchro (3 VME crates): Synchronisation with SPS, prepulse generation, reference clocks for experiments

4. Control & sequencing Power system Cavity controller Beam Control
klystron, power converter, services (cooling water etc.)
control via PLCs
interface via ACSLine, ACSModule FESA classes
Cavity controller
ensemble of FESA classes
overall supervision and logic by ALLLine FESA class
Beam Control
overall supervision and logic (foreseen) by ALLBC FESA class
RF Synchro
ALLSyncCrate FESA class

5. Functions Cavity controllers (per cavity) Beam control (per beam)
FGC name
Channel
Device name
Units
Description
Client Module
RFMDA.UX45.ACSFCA1.B1
ACSCA.1B1.VOLTAGE_I MV
RF voltage I cavity 1 beam 1
Setpoint 1
ACSCA.1B1.VOLTAGE_Q
RF voltage Q cavity 1 beam 1
FCA-right side 2
ACSCA.1B1.COUPLER mm
Coupler position cavity 1 beam 1
Tuner Control 3
Beam control (per beam)
RFMDA.SR4.BC.B1
ALB.B1.MOMENTUM
GeV
Momentum beam 1
Beam Param DSP (postponed) 1
ALB.B1.RSTEERING m
Radial steering beam 1
Beam Pos Module 2
ALB.B1.PL_GAIN
Hz_rad
Phase loop gain beam 1
LLLoops DSP 3
ALB.B1.RL_GAIN
Hz_m
Radial loop gain beam 1 4
ALB.B1.SL_GAIN
Synchro loop gain beam 1 5
ALB.B1.SL_A
Synchro loop A beam 1 6
ALB.B1.FPROG_COARSE Hz
Coarse frequency program beam 1 7
ALB.B1.NOISE_F_CENT
Blowup noise central frequency 8
ALB.B1.NOISE_AMPL
rad
Blowup noise amplitude 9
ALB.B1.NOISE_BW
Blowup noise bandwidth 10
ALB.B1.SL_TAU s
Synchro loop tau beam 1 (no BParams module) 11
ALB.B1.STABLE_PHASE
Stable phase
Beam Phase Module
Beam control (common to both beams)
RFMDA.SR4.BC.
COMMON 1
ALB.B1.FPROG Hz
Frequency program beam 1 (offset from 400MHz)
Dual Freq Prgm Module 2
ALB.B2.FPROG
Frequency program beam 2 (offset from 400MHz)

6. Actions during LHC cycle: injection, ramp
Initial startup (recover from shutdown)
Switch on power (ACSLine:Setting:mode = ON)
Close cavity LL loops with voltage reference from FGC (ALLLine:Setting:mode = ON)
Prepare for injection
Beam control loops state (ALLBCLoops or ALLBC): synchro & phase loops ON, radial loop OFF
Reset of revolution frequency dividers (ALLSyncCrate:RestartVTU)
At each injection
Next injected bucket/ring/intensity? from timing/telegram
Next injected bunch pattern (FESA property, ALLBC)
Ramp, squeeze:
all via functions, no specific actions to be taken

7. Actions during LHC cycle: flat top
Before physics
Rephasing between rings
can be large, time consuming in case of ramp with radial loop
Rephasing to experiments’ bunch clock reference
rapid (few buckets)
Commute to physics reference generator
All the above (will be) implemented in Beam Control FESA class
launched using a FESA property
During physics coast
Frequency trims during physics...?
commute to frequency program DDS
trim DDS frequency
change reference frequency
rephase to reference
commute to reference

8. Conclusion Actions required from sequencer:
Initial switch on of RF power & Low Level
Setup of synchro and beam control loops before injection
Injection requests giving next injected ring/bucket
Bunch intensity via timing?
Bunch pattern via FESA
Rephasing before physics
Frequency trims during physics?
Function management cf. power converters