E-beam stabilization experiences at the ESRF L Zhang, L Farvacque - - PowerPoint PPT Presentation

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E-beam stabilization experiences at the ESRF L Zhang, L Farvacque - - PowerPoint PPT Presentation

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Nanobeam 2002 Lausanne, Switzerland 2-6 September 2002 www.esrf.fr E-beam stabilization experiences at the ESRF L Zhang, L Farvacque European Synchrotron Radiation Facility Outline Introduction Ground vibration Vibration sources

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Nanobeam 2002 Lausanne, Switzerland

2-6 September 2002

E-beam stabilization experiences at the ESRF

L Zhang, L Farvacque European Synchrotron Radiation Facility

www.esrf.fr

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Page 2 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Outline ❚ Introduction ❚ Ground vibration ❚ Vibration sources identification ❚ Mechanical design optimization ❚ Damping device for machine girders ❚ e-beam feedback

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Page 3 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Introduction – e-beam stability

❚ e-beam size at source points

  • RMSvertical = 8 µm
  • RMShorizontal = 59 µm for low-β section, 402 µm for high-β section

❚ e-beam stability requirement

  • 20% emittance growth ∆ε/ε, ~ 10% e-beam size & 10% divergence
  • ∆RMSvertical< 0.8 µm, ∆RMShorizontal< 6 µm (low-β), 40 µm (high-β)

❚ Quadrupole stability requirements

  • e-beam vibration amplification by optics ~ 20 (V), 30 (H)

quadurpole vibration RMSQ-vertical< 0.04 µm, ∆RMSQ-horizontal < 0.2 µm (low-β)

❚ Ground stability requirements

  • quadrupoles vibration amplification : 2 (compared to ground)

ground vibration RMSG-vertical< 0.02 µm, ∆RMSG-horizontal < 0.1 µm (low-β)

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Page 4 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Introduction – X-ray beam stability

❚ ESRF : synchrotron light source ❚ E-beam stability : quadrupoles, girders, ground ❚ X-ray beam stability

  • Sample holder
  • X-ray optics (mirror, monochromator)
  • e-beam source
  • Ground

❚ X-ray beam stability requirement

  • X-ray beam size : 0.1 µm ~ a few cm, 10% of size 0.01 µm
  • Angular stability : better than 0.1 µrad
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Page 5 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Introduction

) ( ) ( f d f G

ε ε ∆

=

“ESRF foundation phase report”, 1987

❚ Transfer function (ground vibration d(f) e-beam emittance growth ) e-beam sensitive to vibrations f > 4Hz

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Page 6 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Ground vibration – versus time

Peak-to-peak displacement (Dpp) in the bandwidth of 1-100 Hz versus time 0.0 0.5 1.0 1.5 2.0 2.5 3.0

08/10/1996 12:00 09/10/1996 00:00 09/10/1996 12:00 10/10/1996 00:00 10/10/1996 12:00 11/10/1996 00:00 11/10/1996 12:00

time (dd/mm/year hh:mm) Dpp (µm)

Orme des Merisiers ESRF SuperACO

Typical values (m)

day night P2P 0.80 0.36 RMS 0.12 0.05 RMS4-100Hz 0.04 0.018 Requirements : ∆RMSG-vertical < 0.02 µm ∆RMSG-horizontal < 0.1 µm

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Page 7 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Ground vibration – 3D spectral displacement

Vertical North-South East-West 10

  • 1

10 10

1

10

  • 5

10

  • 4

10

  • 3

10

  • 2

10

  • 1

10 10

1

Frequency (Hz) spectral displacement (µm) 3D spectral displacement at the site of the ESRF on 9-Oct-1996 t_begin=16:14:59.910

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Page 8 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Vibration source identification

❚ Internal sources

  • Water flow : rubber connection, flexible versus rigid pipes, …
  • Power supply : vibration isolation
  • Ventilations : in SR tunnel, experiment hall, optic table,…

❚ External sources

  • Earthquake
  • Speed bump at the exit of the motorway
  • Road surface near the site (sewer covers, irregularities,…)
  • Speed bump in the site
  • Big machines near the site : compressor, electric-heat co-

generator,water pumps,…

  • Traffic : trains, trolley-bus, trucks, buses,…
  • Bridges near the site
  • Grenoble site (3 Hz)
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Page 9 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Vibration source identification - earthquakes

Date : 03/12/2000, 05:24:00 (local time) Magnitude : 2.3 Epicentre : near Domène France distance : 15 ~ 20 km Date : 21/08/2000, 19:14:56 (local time) Magnitude : 5.0 Epicentre : north of Genes Italy distance : 200 ~ 250 km

averaged : twin=16.384 s tovlp=0.75*twin twin=[17 - 95] s

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Page 10 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Mechanical design optimization

❚ Design guide line :

  • Natural frequencies : as high as possible

low mass, high stiffness

  • Avoid non necessary adjustments : jacks, translation, rotation stages,…
  • Individual versus grouped supports or tables
  • fixations
  • Finite element simulation
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Page 11 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

machine girder – modes identification

before tuning after tuning No f TEST f FEM ∆ f FEM ∆ 1 8.68 8.89 2.4% 8.64

  • 0.5%

2 11.74 11.64

  • 0.8%

11.75 0.1% 3 13.63 12.86

  • 5.6%

13.70 0.5% 4 22.33 22.47 0.6% 22.47 0.6% 5 26.29 26.45 0.6% 26.35 0.2% 6 27.82 27.17

  • 2.3%

27.14

  • 2.5%

7 32.18 31.58

  • 1.9%

31.48

  • 2.2%

8 32.30 33.12 2.5% 33.13 2.6% 9 34.85 36.39 4.4% 36.38 4.4% 10 39.49 38.29

  • 3.0%

38.28

  • 3.1%

natural frequencies comparison

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Page 12 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

machine girder – modes identification

from modal testing from FEA

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Page 13 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Damping device – damping plates

❚ Q-value reduction by a factor of 10 ❚ Stiffness reduction : position drift zoom

Q-value

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Page 14 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Damping device – damping link

❚ Q-value reduction by a factor of 6 ❚ Stiffness increase : 1st natural frequency shifted to higher frequency

GMF : Girder Mounting Fixture FMF : Floor Mounting Fixture VEM : ViscoElastic Material

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Page 15 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

Damping link for machine girder – performance

PSDpk rms4-12Hz µm2/Hz ratio µm ratio noDL 158 11.7 DL 3.2 49 3.1 3.8

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Page 16 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

e-beam motion

Jul00 Oct00 Jan01 Apr01 Jul01 Oct01 2 4 6 8 10 12 14

RMS amplitude (m) of the horizontal motion in the frequency range of 4-12 Hz The RMS amplitude was reduced from 10 m to 2.7 m (4-12 Hz) 12 m to 4 m (4-200 Hz)

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Page 17 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

e-beam motion

the ESRF booster is a 10 Hz fast cycling synchrotron

the operation of the booster :

  • during the weekly day of

Machine Dedicated Time (MDT)

  • around re-injection time

1000 ≈ =

− quadrupole beam e

PSD PSD ratio 30 ≈

− quadrupole beam e

RMS RMS

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Page 18 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

e-beam feedback

❚ Global feedback

  • Vertical : 16 BPMs and 16 correctors
  • Horizontal : 32 BPMs and 24 correctors

(to be implemented)

❚ Local feedback (for Horizontal direction)

  • installed on 4 straight sections
  • 4 steerers + 2 BPMs / bump
  • correction rate : 4.4 KHz
  • Bandwidth : 0.01 to 100 Hz
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Page 19 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

e-beam motion - summary

at the middle of a high-β straight section (βx = 35.4 m) RMS horizontal = 402 µm RMS horizontal ( m) 4-12 Hz 4-200 Hz no damping links (µm) 10 12 with damping links (µm) 2.7 4 damping links + feedback (µm) 0.28 1 at the middle of a high-β straight section (βz = 2,5 m) RMS vertical = 8 µm RMS vertical ( m) 4-12 Hz 4-200 Hz with damping links (µm) (µm) 0.5 1 damping links+feedback (µm) 0.17 0.6

6 µm (low-β) 40 µm (high-β) 0.8 µm

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Page 20 Nanobeam 2002, 2-6 September 2002 E-beam stabilization experiences at the ESRF / L. Zhang, L. farvacque

End

Thank you For your attention