March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 1 Supported by GSI & CERN
Existing bunch-to-bucket transfer schemes
Synchronisation solutions for accelerator facilities
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 2 Supported by GSI & CERN
Plan
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 3 Supported by GSI & CERN
Introduction β Bunch-to-bucket transfer
Bunch-to-bucket transfers are being considered since particles are being accelerated over several machines successively.
Β« Bunch-to-bucket Β» means that a bunch of particle must be deflected from its stable trajectory in a source machine to be injected in the centre of a bucket on its stable trajectory in a target machine.
Source-synchrotron
Target-synchrotron
Ejection septum
Injection septum
Figure : Problem overview
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 4 Supported by GSI & CERN
Introduction β Synchronisation
Extraction
InjectionAcceleration in the source-synchrotron
Acceleration in the target-synchrotron
Ene
rgy
Time
Figure : acceleration cycle, overview
Injection
Acceleration ramp
Ejection
Ene
rgy
mat
chin
g
Pha
se m
atch
ing
Loop
cor
rect
ion
Ene
rgy
Time
Figure : acceleration cycle, the source-machine
Extraction energy
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 5 Supported by GSI & CERN
Introduction β Bucket, Bunch, Batch
An empty bucket
A bunch in its bucket
4 equally spaced bunches
2 batches of 4 bunches each
Batch spacing
Bunch spacing
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 6 Supported by GSI & CERN
Plan
β’ Introduction
β’ Machine synchronisationβ’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 7 Supported by GSI & CERN
πΈππ₯π‘π=πΈπππ
βπΎππ₯π‘π=πΎ πππ
β π½ππ₯π‘π=π½πππ
βπΆπ π πππ£π =π½ πΒΏπΆπ‘ π πππ£
π‘
: Energy of the synchronous particle
With : instant speed of the synchronous particle
Energy matching
Goal of this stage is to ensure that the bunches, which would be sent form the source-machine and the buckets in the target-machine are derived from the same energy level.
πΆ π π πππ£π =π½π=πΆπ‘ π πππ£
π‘
π πππ£π
π πππ£π‘ =πΆπ‘
πΆπ =π π
ππ‘
π π πΉ=h π πππ£
π π πΉπ =πΆπ‘hπ‘
πΆπ hπ π π πΉπ‘
Synchrotronβs circumference
Revolution Frequency
πΆ :π πππ£ :
RF Frequencyπ π πΉ :
Harmonic numberh :
π π πΉ=hπ2π π 0
π΅
βπ΅2β( 1π π πΈ0π )2
vs. B field relation :
depends on the type of the accelerated particles. Since neutrons have no charge, the frequency sweep for accelerated heavy ions is larger than the one for accelerated protons to the same energy.
MeV
MeV
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 8 Supported by GSI & CERN
Batch synchronization (1)
Once the beam energy has been matched, the two-machines-system is periodic of period :
Figure : phase advance
Phase reference
ππππ£π
Phase reference
ππππ£π‘
Figure : phase advance
Phase referencePhase advance
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 9 Supported by GSI & CERN
Batch synchronization (2)
A frequency bump is produced to correct the phase advance:
βπ=(2πβ«π‘0π
β π πππ£ ππ‘)180Β°
β π πππ£
Figure : frequency bump
Bump start
Source-synchrotron
Target-synchrotron
Extraction
Transfer
Injection
πππ₯π‘π ππππ
β π‘ π‘ππππ πππ
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 10 Supported by GSI & CERN
Fine synchronization
V
β π‘
βπΈ
This loop can be a simple phase locked loop or a more sophisticated 1st or 2nd order correction function (PSB and LHC case).
Since the frequency () on which the batch rephased is generally not high enough to ensure the required phase accuracy, a second phase matching is performed on a higher frequency () mostly thanks to a feedback loop.
β π‘ ππππ
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 11 Supported by GSI & CERN
Plan
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 12 Supported by GSI & CERN
Limitations
πππ
=πΎ π‘π2 ππ π
+ππ΅π΅
πππ
=πΎ 2πππ
+πΎ2ππ π
ππ΅π΅
=πΎπ‘π2 πππ
+πΎ 2βπΎ π‘π
2
πΎ2πππ
ππ΅π΅
=πΎ2πππ
+(πΎ 2βπΎπ‘π2 ) ππ π
π=ππ0( π π 0)1πΌπ π΅
πΌπ=ππ (ππ ππ )
π΅
π =π½π2π π
: radius of the beam trajectory : momentum : magnetic field intensity
ππ΅π΅
=πΎ2πππ
+(πΎ 2βπΎπ‘π2 ) ππ π
πππ
=πΎ π‘π2 βπΎ 2
πΎ 2ππ π
Radial excursion: a frequency offset at constant B field results in a radial excursion which canβt be fully handled during the transfer.
0πππ
=πΎ 2βπΎπ‘π
2
πΎπ‘π2 πΎ 2
πππ
0
ππ΅π΅
=πΎπ‘π2 πππ
+πΎ 2βπΎ π‘π
2
πΎ2πππ
ππππ‘
= β πππππ£
=βΞ·π 0π0
πππ ππππ
2π π 0
β π=πππ πππ π
2π π π πππ£β π =
πΎ2βπΎπ‘π2
πΎπ‘π2 πΎ 2
π 0π0
πππ πππ π
2π π π πππ£
Limitation on the frequency rate: the instant speed and the momentum of the synchronous particle are linked.
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 13 Supported by GSI & CERN
Limitations: Adiabaticity
|Ξ©π 0
ππ‘Ξ©π 0
|2πΞ©π 0
=πβ 1
β π‘ππβ1π π πΉ
4β |Ξ·|πΎππππ ππ
βπΈππβ π π πΉ4βπΎππ πππ π
|Ξ·|
The evolution is adiabatic if the relative variation of the synchrotron frequency in one synchrotron period is small :
V
β π‘
βπΈ
This conditions sets also some limits to the shape change ratio of the bucket :
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 14 Supported by GSI & CERN
Plan
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitations
β’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 15 Supported by GSI & CERN
Signal synchronisation
β’ Re-synchronisation: one machine should synchronise on the second one or both machines must synchronise on an external clock. In both case the reference signal must be re-synchronised.
β’ Possibility to wait for a confirmation signal after both machines are perfectly synchronised and phased.
β’ The master machine or the master timing sends the extraction pre-pulse.β’ The different extraction, injection and instrumentation pulses are timed, taking
into account the different hardware delays (kickers, pick-upsβ¦)
ControlTarget
machineSource
machine
Shared timing
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 16 Supported by GSI & CERN
Plan
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timing
β’ Applicationsβ’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 17 Supported by GSI & CERN
Booster β PS and LEIR β PS
In both cases the PS imposes a relative narrow RF-frequency range which is suitable for the transfer. The source-machine must tune its revolution frequency on the PS revolution frequency (with respect of the harmonic number).
Transfer PSB β PS protons:
β’ GeVβ’ GeV/cβ’ kHzβ’ kHzβ’ Gβ’ G
Since the fluctuations of the B-field are not taken into account anymore during the synchronisation process, the frequency matching must be corrected by observing the bunchβs drift at fixed external revolution frequency:β’ and are evaluatedβ’ The B-field is adapted in the target machine
β’ The B-field is adapted in the source machine
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 18 Supported by GSI & CERN
LEIR β PS rephasing
Figure: Measured synchronisation phase for different correctors. Plot (a): second-order PD2 only. Plot (b): third order corrector PID2 obtained by cascading a first-order PI and a second-order PD correctors. Data are acquired every 37.5 ΞΌs.PSB Tests 2008, M.E. Angoletta
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 19 Supported by GSI & CERN
PS β SPS (1)
Transfer for protons :
πΆπππ
πΆππ =11 π π πΉπππ= π π πΉ
ππβπΆπππ hππ
πΆππhπππ=1
hπππ=11hππ
hπππ=4620
hππ=420
Transfer for Pb ions:
200.264545 MHz at 26 GeV
25 ns bunch spacing
hπππ=4653
hππ=423
199.926 MHz at 5.1 GeV/u
100 or 200 ns bunch spacing
199.948 MHz at 14 GeV
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 20 Supported by GSI & CERN
PS β SPS (2)
PEX.W10
PEX.SSYNC
PEX.SSYNC2
PEX.MW8RF
TFID
TREV
TREV
TRF
TFID TREV
TREV TRF
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 21 Supported by GSI & CERN
PS β SPS (3)
π π
Pre-pulse PS
Warning PS
Kicker PS
Kicker SPS
Master timingPEX.W10
Sync Sync2
2 ms
8 ms
PEX.WSPS
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 22 Supported by GSI & CERN
PS β SPS rephasing
Figure: PS-SPS synchronisation (phase advance in yellow)Heiko Damerau
Extraction
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 23 Supported by GSI & CERN
SPS β LHC (1)
Transfer for protons :
πΆπΏπ»πΆ
πΆπππ =277
π π πΉπΏπ»πΆ
2= π π πΉ
π ππβπΆπΏπ»πΆhπππ
πΆπππhπΏπ»πΆ=2 hπΏπ»πΆ=2
277hπππ
Bunch compressed to 1.7 ns2100 bunches with 25 ns bunch spacing
Transfer for ions:
MHz,
Bunch compressed to 1.2 ns358 bunches with 200 ns bunch spacing
MHz at 450 GeV/c T 4620 35640
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 24 Supported by GSI & CERN
SPS β LHC (2)
π π
Pre-pulse SPS
Extraction SPS
Injection LHC BT
Injection LHC BI
~90 ms
~990 ms
SEX.F-W20
17 ms
60000 300 s
376222
7
2
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 25 Supported by GSI & CERN
SPS β LHC rephasing
Ph
ase
ad
van
ce
Figure: SPS-LHC synchronisationThomas Bohl
LHC
SPS
Periodicity of 1 turn LHC turns SPS
at most turn rephasing ms beating
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 26 Supported by GSI & CERN
Plan
β’ Introductionβ’ Machine synchronisation
β’ Energy matchingβ’ Batch synchronisationβ’ Fine synchronisation
β’ Limitationsβ’ Beam synchronous transfer timingβ’ Applications
β’ Booster β PS and LEIR β PS β’ PS β SPSβ’ SPS β LHC
β’ Remaining issues
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 27 Supported by GSI & CERN
Remaining issues
β’ Each synchronization scheme is designed to fit in the machine and energy requirements according to the type of the accelerated particles.
β’ Since the batch matching starts only after acceleration, significant time is lost during this procedure on the flat top.
β’ Some schemes are being considered to start the synchronization during acceleration.
β’ Synchronising more than two machines according to eventually different reference frequencies can be challenging
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 28 Supported by GSI & CERN
Acknowledgement
Thank you for your attention
This short study has been led over four quite intensive weeks at CERN. Many aspects of the bunch-to-bucket transfer however remain to be discussed and investigated before a reliable time-efficient scheme might be plotted. For their helpful pieces of advise and their kindness I want to thank : Maria Elena Angoletta, Philippe Baudrenghien, Thomas Bohl, Elena ChapochnikovaHeiko Damerau, Harald Klingbeil,
To be continuedβ¦
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 29 Supported by GSI & CERN
Sources
β’ DSP Software Implementation, Dr. H. Klingbeil, GSI documentation, Version 41, 04.01.2012.
β’ Modellierung des Regelungs- und Steuerungssystems einer Beschleunigungseinheit fΓΌr Synchrotrons, U. Hartel, TU-Darmstadt, Diplomarbeit, 02.05.2011.
β’ Main Technical Parameters of SIS100, N. Pika, GSI, 2010.
β’ The white rabbit project, J. Serrano, P. Alvarez, M. Cattin, E. Garcia Cota, J. Lewis, P. Moreira, T. Wlostowski, G. Gaderer, P. Loschmidt, J. Dedi\v{c}, R. BΓ€r, T. Fleck, M. Kreider, C. Prados, S. Rauch, CERN, Cosylab, GSI, 2009.
β’ Entwurf und Implementierung eines digitalen Phasen- und Amplitudendetektors fΓΌr eine HF-BeschleunigerkaviΓ€t,Tobias Wollmann, TU- Darmstadt, Diplomarbeit, 2009.
β’ Time Optimal Synchronisation Procedure and Design of Associated Feedback Loops, F. Pedersen, M.E. Angoletta, CERN, 2008.
β’ Rephasing SPS-LHC,P. Baudrenghien, A. Butterworth, F. Dubouchet, A. Pashnin, J. Noirjean, R. Olsen,CERN, 2008.
β’ Rephasing,P. Baudrenghien, CERN, 2007.
β’ Synthesizer Controlled Beam Transfer from the AGS to RHIC,J. DeLong, J. M. Brennan, W. Fischer, T. Hayes, K. Smith, S. Valentino, Brookhaven National Laboratory, Upton N.Y. 11973, 2001.
β’ Vorschlag eines Beschleunigungsschemas fΓΌr die Maschinen SIS12/18 und SIS100 bei GSI, H. Damerau, M. Emmerling, P. HΓΌlsmann, GSI, 2001.
β’ A Straightforward Procedure to Achieve Energy Matching Between PSB and PS, M. Benedikt, H. Damerau, S. Hancock, CERN, 2000.
β’ Beam Control for Protons and Ions, P. Baudrenghien, CERN, 1999.
β’ SPS Beams for LHC: RF Beam Control to Minimize Rephasing in the SPS, P. Baudrenghien, T. Linnecar, D. Stellfeld, U. Wehrle, CERN, 1998.
β’ Proposal to Transfer 8 SPS Bunches into 8 LEP Buckets,P. Baudrenghien, E. Brouzet, D. Boussard, T. Linnecar,CERN, 1991.
β’ Synchronisation RF CPS-SPS-LEP. MΓ©thode et ContrΓ΄le dans le SPS,P. Baudrenghien, C. Despas, CERN, 1989.
β’ Matching the Energies of the CPS and SPS MachinesR.J. Lauckner, CERN, 1988.
β’SIS Parameter List,B. Franczak, GSI, 1987.
March 20th 2014 | TU Darmstadt | Fachbereich 18 | Institut Theorie Elektromagnetischer Felder | Thibault Ferrand, MSc | 30 Supported by GSI & CERN
Existing bunch-to-bucket transfer schemes
Synchronisation solutions for accelerator facilities