beam dynamics studies for the hybrid multi bend …...beam dynamics studies for the hybrid multi...

Beam dynamics studies for the Hybrid Multi Bend Achromat lattice of the

ESRF-EBS 6GeV upgrade and future 3GeV storage rings

S.M.Liuzzo, ESRF, Tsukuba, 06/July/2016 on behalf of the ESRF beam dynamics group and ESRF-EBS upgrade project team

OUTLINE

ESRF upgrade to ultra low horizontal natural emittance (EBS) -  Beam dynamics issues -  Emittance optimization -  Linear and non linear optics optimization -  Tolerances to alignment, field, multipole and survey errors Technical challenges -  Magnets -  Losses -  Impedance -  Bending magnets beamlines Progress of the project 3GeV HMBA -  Linear and non linear optics optimization

26/07/2013

l KEK Accelerator Seminar l June 2016 l S.M.Liuzzo

CURRENT ESRF, ACCELERATOR CHAIN LAYOUT AND MAIN PARAMETERS

26/07/2013


ERSF Storage ring

C=844 m E=6 GeV

τ= 12-60 h * VRF= 8 MV εx=4 nm rad εy= 5 pm rad

I = 40-200 mA *

(*) according to filling mode

0.2-6GeV

6GeV

ABOUT ESRF: EUROPEAN SYNCHROTRON RADIATION FACILITY


Cell 4 Injection, Cell 5, 7, 25 RF

26/07/2013

RADIATION SPECTRA AND COHERENT FRACTION

ESRF upgrade

Hor. Emittance [pmrad] 4000 135

Vert. Emittance [pmrad] 5 5 Energy spread [%] 0.1 0.09 βx[m]/βz [m] 37/3 6.9/2.6

Brilliance Coherence


E.B.S. : Extremely Bright Source

26/07/2013

Upgrade ESRF

Energy [GeV] 6.00 6.04

Tunes 75.21, 26.34 36.44, 13.39

Emittance x [pmrad] 135 4000

Emittance y (target) [pmrad] 5 5

Energy loss per turn [MeV] 2.6 4.9

RF voltage (acceptance) [MV] 6 (5.6%) 9 (4%)

Chromaticity 6, 4 4, 7

Circumference [m] 843.98 844.39

Energy spread [%] 0.095 0.106

Beam current [mA] 200 200

Lattice type HMBA DBA

Touschek lifetime [h] ~20 ~60

MAIN LATTICE PARAMETERS


26/07/2013

REDUCE EMITTANCE FOR HIGHER BRILLIANCE

26/07/2013


B = Photons/(s mm2 mrad2 BandWidth ) Diffraction limit, at λ=10nm is 10 pmrad (lower ε does not increase B)

✏(x,y) <�

4⇡

Combined function magnets

Small bending angles

Small beam Energy

Optics: Twiss and dispersion

Strong focusing

Strong chromaticity

Non linearity

X-ray energy Available space, €

Beam lifetime

Injection

Aperture

CURRENT ESRF STORAGE RING LATTICE: DOUBLE BEND ACHROMAT

16 superperiods (mirrored cell above, 32 cells in total). Achromatic condition broken for lower emittance (εx from 7 nmrad to 4 nmrad ).


26/07/2013

Already a “low emittance lattice”

sextupoles

quadrupoles

dipoles

undulators undulators BM source

PROPOSED LATTICE LAYOUT FOR THE UPGRADE IN 2020: HYBRID MULTI BEND ACHROMAT

26/07/2013


Strong focusing (large K1) Dx, βx~0 @ 7 dipoles

2 Local dispersion bumps at –I, large Dx @ sext. for chromaticity

correction with low sextupole fields (K2) Ex = 0.135nm

sextupoles

quadrupoles

dipoles

undulators undulators

Dipoles longitudinal gradient

Dipoles + quadrupole gradient

BM source

DIPOLE FIELDS OPTIMIZATION TO REDUCE EFFECTIVE EMITTANCE AT ID

26/07/2013


Cell is symmetric. Vary the dipole fields to minimize the horizontal effective emittance (σxσx’): •  Fixed total angle •  Fixed total length •  Fixed key optics

(quadruoples)

4 6 8 10 12 140

0.5

1B

[T

]

s [m]

!

x= 0.3625 "

x=1.6361e!10 U

0=2.8921 MeV

!z= 0.8625 "

z=0.0000e+00 #

x@ID=9.7385e!03 $

x$

x’@ID=1.8389e!10

0

10

20

dis

pe

rsio

n ,

H [

cm

]

B [T]#

x [cm]

H [10!2]

4 6 8 10 12 140

0.5

1

B [

T]

s [m]

!

x= 0.3625 "

x=1.3520e!10 U

0=3.3747 MeV

!z= 0.8625 "

z=0.0000e+00 #

x@ID=1.4701e!02 $

x$

x’@ID=1.7615e!10

0

10

20

dis

pers

ion

, H

[cm

]

B [T]#

x [cm]

H [10!2]

εx = 164 pm rad

εx = 135 pm rad O

PTIM

IZER

: -18%

Stronger bending where small beta and dispersion

ADVANTAGES AND CHALLANGES OF H.M.B.A. CELL

26/07/2013


Challenges: -  Strong gradients -> small apertures -  Limited free space -  Installation in preexisting infrastructure -  Reduced Touschek lifetime and dynamic aperture for injection

Advantages: -  Lower emittance, higher brilliance -  Lower RF power (6.5 instead of 8.5 MV) -  Lower consumption (permanent dipoles) -  (for ESRF) independent P.S.

DYNAMIC APERTURE OF UPGRADE LATTICE CELL, WITHOUT INJECTION SECTION

26/07/2013


Off-axis injection requires large dynamic aperture at injection Injection in a standard straight section has an efficiency of 22% (average of 10 seeds of errors), Two solutions are

adopted: 1) An ad-hoc injection cell with high beta 2) Optimized injected beam shape and emittance

Stored beam Kicked beam

septum

Injected beam 3σh=4.5 mm

Injection bump

S3 septum

K3 K2 K1 K4

S1-S2

INJECTION CELL ESRF UPGRADE (S28A)

Identical to arc cell. Identical to arc cell.

Touschek Lifetime With errors Without errors

Without injection 24.5 h 55.6 h

With injection 21.3 h 35.1 h

With injection + sextupoles 21.3 h 43.1 h

Retuning of the sextupoles in the injection cell. Sextupoles are not re-adjusted after setting errors and correction.

βx=22m , standard ID straight section βx=6.9m


26/07/2013

INJECTION CELL TUNING

26/07/2013


OP

TIMIZE

D

The injection cell brakes the periodicity of the lattice, with a relevant impact on Touschek lifetime. It is possible to tune the sextupoles and octupoles of the injection cell to restore the periodicity of the chromatic RDT, chromatic optics and dispersion.

Courtesy N.Carmignani

DYNAMIC APERTURE OF UPGRADE LATTICE CELL, WITH INJECTION SECTION

26/07/2013


Off-axis injection requires large dynamic aperture at injection Injection in ad-hoc straight section has an efficiency of 62% (average of 10 seeds of errors), Two solutions are



septum

Injected beam 3σh=4.5 mm

Injection bump

INJECTOR UPGRADE: EMITTANCE REDUCTION

The injection efficiency is a critical point for the new machine, so the following improvements are foreseen: Reduction of the horizontal emittance:

•  Booster linear optics optimisation: εx: 120 to 95 nm On-going tests •  Work off-energy by shifting the RF frequency: εx: 95 to 60 nm Tested (EBS Inj. eff. 83%) •  Couple H and V emittances via equal tunes: εx: 60 to 30 nm Tested (EBS Inj. eff. 92%)

Beam shaping using a sextupole in the TL2 transfer line (+2% injection efficiency):

1st MAC MEETING – 14-15 April L. Farvacque

•  The TL2 optics is ready and working •  The sextupole is installed and

connected since March 2015. •  Tests started consistent with

expected (smaller optimal horizontal beta at end of TL2)

X'

Stored beam Injected beam

X

X' Emittance shaping using a sextupole Classical injection

Septum

S.White et al. IPAC2016, and work under publication

Courtesy T.Perron, L.Farvacque, S.White

DYNAMIC APERTURE OF UPGRADE LATTICE CELL, WITH INJECTION SECTION

26/07/2013


Off-axis injection requires large dynamic aperture at injection Injection in ad-hoc straight section has an efficiency of 92% (average of 10 seeds of errors), Two solutions are



septum

Injected beam 3σh=4.5 -> 2.2 mm

Injection bump

LINEAR AND NON LINEAR OPTIMIZATIONS

Lattice optics and non linear elements tuning is devoted to the improvement of Injection Efficiency and Touschek lifetime. However often the two optimizations are often in contrast.

26/07/2013


0 10 20 30 40 50

!0.06

!0.04

!0.02

0

0.02

0.04

0.06

s (m)

Mom

entu

m a

pert

ure

3.0 MV4.0 MV5.0 MV6.0 MV

⌧t /p

"y�z

Ib�3acc

After conditioning: Vacuum lifetime ~300h, Touschek lifetime < 20h.

1

⌧=

1

⌧t+

1

⌧vac

βx , ηx

βy, αy, ηx

βy

µx, µy

M(1,2), M(3,4), -I transformation

LINEAR LATTICE OPTIMIZATIONS

The variables used for the cell optimization are linear parameters and nonlinear magnets (3 sextupole families and 1 octupole). Each parameter is linked to mainly one parameter of interest for Beam dynamics (variations of tune with amplitude and momentum, chromaticity, emittance). These parameters are tuned empirically and using NSGAII (a.k.a. MOGA).


26/07/2013

OTHER OPTIMIZATIONS: CHROMATICITY SCANS

High chromaticity improves lifetime probably due to overcompensation at small amplitude of path lengthening effects.


26/07/2013

The strong path lengthening effect implies that the use of an harmonic cavity could help to increase D.A.

Nat.Chrom.

(10,10)

(-10,-10)

OPTIMIZATIONS OF LATTICE WITH ERRORS


Optimizations computing the objective functions on several seeds of errors, usually 10. Each point in the plot is the average on 10 error seeds! For each seed on 1 core: 3-4h errors and correction 1h Dynamic aperture 3h Touschek lifetime A very large computer power is needed.

NSGAII optimization, with free chromaticities. Optimum values have positive chromaticities: 10-5.

26/07/2013


Starting point

Pareto front of optimal solutions

Initial population

TUNE WORKING POINT SCANS


In this figures: sextupoles optimized at (.23, .34) and no injection cell

26/07/2013

NEEDS AND CHALLENGES FOR OPTICS CORRECTION: CORRECTORS AND BPM


Correctors in all sextupoles plus 3 separated correctors All magnets have independent power supplies

10 BPM 9 correctors, horizontal,

vertical and skew quadrupole in all

sextupoles and 3 dedicated correctors

16 quadrupoles

DQ DL DL DQ

26/07/2013

EXAMPLE OF CORRECTION OF RANDOM ERRORS

Simulation of the whole correction sequence, from transfer line to ORM* fit.

-  Find a closed orbit correcting open trajectories

-  Correct orbit

-  Create lattice error model fitting ‘measured’ RM (partial, 14/288 cor.)

ORMerr = [Δ ORM/ΔK ] * ΔKfit

-  Compute Resonance Driving Terms and correct simultaneously normal and skew quadrupole RDT and dispersion

-  Fix tune and chromaticity

-  Iterate a few times

*Orbit Response Matrix

Closed orbit only

After tuning

Current ESRF

X [µm] 160(675) 116 61 Y [µm] 111(250) 58 70

Dx-Dx0 [m] 0.017 0.001 0.028 Dy [m] 0.002 0.0002 0.002

β-beating x [%] 26.2 0.7 4.9 β-beating y [%] 26.5 0.8 3.3

Tune x [.21] 0.208 0.21 0.44 Tune y [.34] 0.336 0.34 0.39

Q’x [6] 6.328 6.00 3.89 Q’y [4] 3.971 4.00 6.92

εx [134.7 pmrad] 250.4 134.7 4099 εy [ 0.04 pmrad] 2.2 0.18 3.123


26/07/2013

DISPERSION AND BETA BEATING CORRECTION (NORMAL AND SKEW QUAD.)


26/07/2013

1) Create lattice error model fitting ‘measured’ Response Matrix (partial,

14/288 correctors)

ORMerr = [Δ ORM/ΔK ] * ΔKfit 2) Compute normal (K1s) and skew (K1s) quad. Resonance Driving Terms: these quantities are linear with K1 and K1s. 3) Correct simultaneously RDTs and dispersion à correct beta-beating, coupling and dispersion .

IMPACT OF ALIGNMENT ERRORS

26/07/2013


The above correction scheme is used for each simulated lattice. The same figure generated for D.A., emittances, optics,… and several other error sources to determine tolerable lattice errors.

See legend for error ranges

S25, no injection cell

TOLERABLE RANDOM ERRORS

Each error, on each magnet family, is studied individually looking at the dependence of DA, lifetime, emittances and all relevant parameters vs error amplitude.

Required: DX DY DS DPSI DK µm µm µm µrad 10^-4

DL >100 >100 1000 500 10

DQ, QF[68] 70 50 500 200 5

Q[DF][1-5] 100 85 500 500 5

SFD 70 50 500 1000 35

OF 100 100 500 1000

Sextupoles and high gradient quadrupoles are the most relevant limitations, nevertheless, these alignment specifications are currently achievable.

(DX=DY=60µm, 84 µm between two magnets). l KEK Accelerator Seminar l June 2016 l S.M.Liuzzo

26/07/2013

MULTIPOLE ERRORS


26/07/2013

Simulated systematic and random multipole errors to estimate tolerance

define tolerated DG/G@7mm

CURRENT ESRF SURVEY

X-ray beam direction is strongly influenced by the position of the storage ring and orbit distortion. The colleagues from the alignment group provided 50 simulation of possible lattice positioning errors for the EBS storage ring lattice.


26/07/2013

!0.01 0 0.01 0.02

!0.015

!0.01

!0.005

0

0.005

0.01

0.015

x [m]

y [m

]

X!ray beam position after: 60 m

S28A surv.ESRF surv.

INSTALLATION OF THE STORAGE RING ON THE PRESENT SURVEY

All ID are assumed to be at 60m from the source. The position of the beam after 60m is very similar for ESRF and S28A considering the current survey measurement. The position if the ring was aligned on the reference circumference would be about (0,0) for al ID.

Current (simulated) position of the X-ray at the beamline

position of the X-ray at the beamline for S28A on the same survey


26/07/2013

SUMMARY OF ERROR IMPACT

26/07/2013


Studied and selected error sources provide DA, injection efficiency and Touschek lifetimes within the requirements

Systematic and random multipole errors Survey errors

Alignment and main field errors

S28C

LOSS SIMULATIONS

26/07/2013


The simulation of Touschek losses allowed to conceive a collimation scheme that concentrates Touschek losses on two horizontal scrapers without affecting lifetime. These simulations are also used for radioprotection issues.

Courtesy R.Versteegen

IMPEDANCE BUDGET

26/07/2013


Total impedance budget comparable to current machine impedance: Z=0.65 Ω

Courtesy S.White

BUNCH LENGTHENING VS CURRENT

26/07/2013


Operating modes: 200mA / 876 bunches Lifetime: 18.9 ± 1.1 h 96mA / 16 bunches Lifetime: 1.9 ± 0.1 h 40mA / 4 bunches Lifetime: 1.1 ± 0.1 h Continuous top-up since April 2016


MAGNETS DESIGN

26/07/2013


Courtesy G. Le Bec

BENDING MAGNET RADIATION SOURCES

26/07/2013


Courtesy P.Raimondi, J.Chavanne

PROJECT STATUS

26/07/2013


Courtesy P. Raimondi

3 GEV HMBA

26/07/2013


HMBA@3GeV, 506m D.A.@ID, no errors: 8mm Touschek Lifetime: 9.4h

b2 < 56 T/m, b3<1000 T/m2

This lattice has relaxed features compared to ESRF-EBS 6GeV HMBA: lower field magnets, more space between magnets, no octupoles.

26/07/2013


Lattice optimizations A slow but rewarding iterative process of optimization led to the lattice presented here. The optimization shown on the sides are: •  Optics, Sextupoles: 6.5h lifetime and 8mm DA •  Dipole fields (at fixed optics)

•  Longitudinal gradient in DL decrease emittance of 20pmrad and increase dispersion at sextupoles by 5%

•  DQ length to increase dispersion at the sextupoles

•  Dispersion at ID can further decrease the emittance, stronger sextupoles

•  Working Point scan with small errors over several units (6.5h to 9.4h lifetime)

Final DA is comparable to ESRF-EBS 6GeV HMBA.

26/07/2013


DA comparable to ESRF-EBS 6GeV HMBA at IDs without errors.

3 GEV LATTICE DESIGNS COMPARISON : PERFORMANCE FACTOR

26/07/2013


MAX IV [1] Sirius [3] DTBA [4] HMBA SSRF-U [5]

Circ. [m] 528 518.4 561 506 432 #cells 20 20 24 22 20

Emittance 330 280 100 140 203

Jx 1.8 1.31 1.38 1.42 2 Tune 42.24,16.27 44.60,12.40 57.20,20.30 54.59,15.43 43.22,17.31

Nat. Chrom. -50,-50 -113,-80 -105,-79 -88,-71 -74.2,-59.3

Drift [%] 17.9 27.1 34.7 25.2 25.9 performance 54 97 347 179 128

Performance = Drift [%] / emittance [nm]

More space for undulators, smaller emittance

OUTLINE FOR QUESTIONS

ESRF upgrade to ultra low horizontal natural emittance (EBS) -  Beam dynamics issues -  Emittance optimization -  Linear and non linear optics optimization -  Tolerances to alignment, field, multipole and survey errors Technical challenges -  Magnets -  Losses -  Impedance -  Bending magnets beamlines Progress of the project 3GeV HMBA -  Linear and non linear optics optimization

26/07/2013


REFERENCES

[1] J.C. Biasci et al. , “A low emittance lattice for the ESRF”, Synchrotron Radiation News, vol. 27, Iss.6, 2014.

[2] “ESRF upgrade programme phase II”, ESRF, December 2014.

[3] N.Carmignani et al., “ Linear and Nonlinear Optimizations for the ESRF Upgrade Lattice”, TUPWA013, IPAC’15, Richmond, Virginia,USA (2015).

[4] S.M. Liuzzo et al., “ Influence of errors in the ESRF upgrade lattice”, TUPWA014, IPAC’15, Richmond, Virginia,USA (2015).

[5] J. Chavanne, "Implementation of short wigglers as photon sources for the bending magnet beamlines in the new ESRF lattice", ESRF, Grenoble, France, 01-15/IDM, Sep. 2015.

[6] S. White et al., “Horizontal phase space shaping for optimized off-axis injection efficiency ”, THPMR016, These Proceedings, IPAC’16, Busan, Korea (2016).

[7] B. Nash, et al., “New Functionality for Beam Dynamics in Accelerator Toolbox (AT)”, MOPWA014, IPAC’15, Richmond, Virginia, USA (2015).

[8] R. Versteegen et al., “Collimation scheme for the ESRF upgrade”, TUPWA016, IPAC’15, Richmond, Virginia,USA (2015).

[9] R. Versteegen et al., “Modelling of beam losses at the ESRF”, TUPWA016, IPAC’15, Richmond, Virginia,USA (2015).

[10] S.M. Liuzzo et al., “Updates on lattice modelling and tuning for the ESRF-EBS upgrade lattice”, TUPWA014, IPAC’16, Busan, Korea (2016).

[11] A. Alekou et al., “Study of a Double Triple Bend Achromat (DTBA) Lattice for a 3 GeV Light Source”, WEPOW044, Busan, Korea (2016).

26/07/2013


beam dynamics studies for the hybrid multi bend …...beam dynamics studies for the hybrid multi...

Documents