on nanosecond timescales Neven Blaskovic Kraljevic FONT group, John - - PowerPoint PPT Presentation

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on nanosecond timescales Neven Blaskovic Kraljevic FONT group, John - - PowerPoint PPT Presentation

Jan 21, 2024 365 likes •863 views

Nanometre-level stabilisation on nanosecond timescales Neven Blaskovic Kraljevic FONT group, John Adams Institute, Oxford University About me Madrid (Spain) Born & raised Neven Blaskovic Kraljevic 2 About me Madrid Oxford (Spain)

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SLIDE 1

Nanometre-level stabilisation

  • n nanosecond timescales

Neven Blaskovic Kraljevic FONT group, John Adams Institute, Oxford University

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SLIDE 2

About me

Neven Blaskovic Kraljevic 2

Born & raised Madrid (Spain)

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SLIDE 3

About me

Neven Blaskovic Kraljevic 3

Born & raised MPhys & DPhil Madrid (Spain) Oxford (UK)

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SLIDE 4

About me

Neven Blaskovic Kraljevic 4

Born & raised MPhys & DPhil Travelled for experiment Madrid (Spain) Oxford (UK) Tsukuba (Japan)

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SLIDE 5

Outline

Neven Blaskovic Kraljevic 5

  • Introduction

– Feedback at a linear collider – International Linear Collider – Feedback on Nanosecond Timescales

  • Experimental setup at Accelerator Test Facility
  • Beam position monitor signal processing
  • Modes of feedback operation
  • Results
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SLIDE 6

Introduction

Feedback at a Linear Collider

Neven Blaskovic Kraljevic 6

  • Successful collision of bunches at a linear

collider is critical

  • A fast position feedback system is required

Misaligned beams at interaction point (IP) cause beam-beam deflection

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SLIDE 7

Neven Blaskovic Kraljevic 7

  • Successful collision of bunches at a linear

collider is critical

  • A fast position feedback system is required

Introduction

Feedback at a Linear Collider

Misaligned beams at interaction point (IP) cause beam-beam deflection Measure deflection on

  • ne of outgoing beams

(beam position monitor)

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SLIDE 8

Neven Blaskovic Kraljevic 8

  • Successful collision of bunches at a linear

collider is critical

  • A fast position feedback system is required

Misaligned beams at interaction point (IP) cause beam-beam deflection Measure deflection on

  • ne of outgoing beams

Correct orbit of next bunch (correlated to previous bunch due to short bunch spacing)

(beam position monitor)

Introduction

Feedback at a Linear Collider

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SLIDE 9

Introduction

International Linear Collider (ILC)

Neven Blaskovic Kraljevic 9

  • Proposed linear electron-positron collider
  • Centre-of-mass energy: 250-1000 GeV
  • Vertical beamsize: 5.9 nm
  • Bunch separation: 554 ns

ILC Technical Design Report

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SLIDE 10

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 10

  • Test bed for the International Linear Collider
  • Facility located at KEK in Tsukuba, Japan
  • Goals:

– 37 nm vertical spot size at final focus – Nanometre level vertical beam stability

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SLIDE 11

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 11

Electron source 90 meters

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SLIDE 12

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 12

1.28 GeV linear accelerator Electron source 90 meters

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SLIDE 13

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 13

Damping ring Electron source 1.28 GeV linear accelerator 90 meters

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SLIDE 14

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 14

Damping ring Electron source Extraction line Final focus Model interaction point (IP)

  • f a collider

1.28 GeV linear accelerator 90 meters

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SLIDE 15

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 15

Damping ring Electron source Extraction line Final focus Model interaction point (IP)

  • f a collider

Feedback system

1.28 GeV linear accelerator 90 meters

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SLIDE 16

Introduction

Accelerator Test Facility (ATF) at KEK

Neven Blaskovic Kraljevic 16

  • ATF can be operated with 2-bunch trains in

the extraction line and final focus

  • The separation of the bunches is ILC-like

(tuneable up to ~300 ns)

  • Our prototype feedback system:

– Measures the position of the first bunch – Then corrects the path of the second bunch

  • Train extraction frequency: ~3 Hz
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SLIDE 17

Introduction

Feedback on Nanosecond Timescales (FONT)

Neven Blaskovic Kraljevic 17

  • Low-latency, high-precision feedback system
  • We have previously demonstrated a system

meeting ILC latency, BPM resolution and beam kick requirements

  • We have extended the system for use at ATF
  • We aim for nanometre level beam stabilisation
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SLIDE 18

Neven Blaskovic Kraljevic 18

P3 P2 P Stripline BPM

  • 12 cm long strips
  • 12 mm radius
  • On x and y mover system

Experimental Setup

beam

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SLIDE 19

Neven Blaskovic Kraljevic 19

P3 P2 for stripline BPM

  • Analogue: latency 15 ns
  • Dynamic range of ±500 μm
  • Resolution of ~300 nm

Σ Δ BPM top BPM bottom Processor Processor Processor

Experimental Setup

beam

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SLIDE 20

Neven Blaskovic Kraljevic 20

P3 P2 Processor Processor IPB IPB Cavity BPM at beam waist

  • C-band: 6.4 GHz in y
  • Low Q: decay time < 30 ns
  • Resolve 2-bunch trains

Experimental Setup

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SLIDE 21

Neven Blaskovic Kraljevic 21

P3 P2 for cavity BPM

  • Analogue, 2-stage downmixer
  • Developed by Honda et al.
  • Resolution of ~50 nm

Processor Processor Processor IPB Processor

Experimental Setup

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SLIDE 22

Neven Blaskovic Kraljevic 22

P3 Processor P2 Processor IPB Processor Board Board Board

  • 9 ADC channels at 357 MHz
  • 2 DAC channels at 179 MHz
  • Xilinx Virtex 5 FPGA

Experimental Setup

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SLIDE 23

Neven Blaskovic Kraljevic 23

P3 Processor P2 Processor Amplifier Amplifier Amplifier IPB Processor Board Board

  • Made by TMD Technologies
  • ± 30 A drive current
  • 35 ns rise time (90 % of peak)

Amplifier

Experimental Setup

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SLIDE 24

Neven Blaskovic Kraljevic 24

P3 Processor P2 Processor K2 Amplifier IPK Amplifier K1 Amplifier IPB Processor Board Board

  • Vertical stripline kicker
  • 30 cm long strips for K1 & K2
  • 12.5 cm long strips for IPK

K Kicker

Experimental Setup

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SLIDE 25

Neven Blaskovic Kraljevic 25

for stripline BPM Σ Δ BPM top BPM bottom Processor

Stripline BPM Signal Processing

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SLIDE 26

Stripline BPM Signal Processing

Neven Blaskovic Kraljevic 26

As the bunch travels through the BPM, it induces a bipolar signal on the strips In the frequency domain, this signal peaks at ~700 MHz

  • R. J. Apsimon et al., PRST-AB, 2015
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SLIDE 27

Stripline BPM Signal Processing

Neven Blaskovic Kraljevic 27

The top and bottom strips are used to measure the vertical beam position The ‘difference over sum’ of the two signals gives the beam position

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SLIDE 28

Neven Blaskovic Kraljevic 28

Stripline BPM Signal Processing

The signals from the two strips are subtracted using a 180° hybrid and added using a coupler simplified schematic

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SLIDE 29

Neven Blaskovic Kraljevic 29

Stripline BPM Signal Processing

An external 714 MHz local oscillator (LO) downmixes the signals to baseband The beam position is proportional to 𝑊

Δ/𝑊 Σ

simplified schematic

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SLIDE 30

Neven Blaskovic Kraljevic 30

for cavity BPM Processor

Cavity BPM Signal Processing

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SLIDE 31

Cavity BPM Signal Processing

Neven Blaskovic Kraljevic 31

Reference cavity Monopole mode frequency (in y) ~6426 MHz IPB cavity Dipole mode frequency (in y) ~6426 MHz

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SLIDE 32

Neven Blaskovic Kraljevic 32

Cavity BPM Signal Processing

The IPB and reference cavity signals are downmixed using a common, external 5712 MHz LO simplified schematic

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SLIDE 33

Neven Blaskovic Kraljevic 33

Cavity BPM Signal Processing

The IPB signal is downmixed using the reference cavity signal as LO The I and Q output signals at baseband are used to obtain the beam position simplified schematic

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SLIDE 34

IPK IPB

Neven Blaskovic Kraljevic 34

P3 Processor P2 Processor K2 Amplifier Amplifier K1 Amplifier Processor Board Board

  • Coupled-loop feedback

system allows correction

  • f both position & angle
  • P2 and P3 are used to

drive K1 and K2

  • Latency: 134 ns
  • Effect measured at

witness BPM MFB1FF, located 30 meters downstream from P3

Upstream Feedback

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SLIDE 35

Neven Blaskovic Kraljevic 35

Upstream Feedback

FB Off Jitter: 1.80 ± 0.06 μm FB On Jitter: 1.70 ± 0.05 μm FB Off Jitter: 1.56 ± 0.05 μm FB On Jitter: 1.66 ± 0.05 μm FB Off Jitter: 29.9 ± 1.0 μm FB On Jitter: 29.4 ± 0.9 μm Bunch 1 P2 P3 MFB1FF

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SLIDE 36

Neven Blaskovic Kraljevic 36

Upstream Feedback

FB Off Jitter: 1.74 ± 0.06 μm FB On Jitter: 0.44 ± 0.01 μm FB Off Jitter: 1.55 ± 0.05 μm FB On Jitter: 0.61 ± 0.02 μm FB Off Jitter: 27.5 ± 0.9 μm FB On Jitter: 8.3 ± 0.3 μm Bunch 2 P2 P3 MFB1FF

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SLIDE 37

Neven Blaskovic Kraljevic 37

Upstream Feedback

FB Off Correlation: 96.9 ± 0.3 % FB On Correlation: –25 ± 4 % FB Off Correlation: 93.3 ± 0.6 % FB On Correlation: +15 ± 4 % FB Off Correlation: 98.3 ± 0.2 % FB On Correlation: –14 ± 4 % P2 P3 MFB1FF

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SLIDE 38

P3 P2 K2 K1

Neven Blaskovic Kraljevic 38

Processor Processor Amplifier Amplifier Amplifier Processor Board Board IPK IPB

Interaction Point Feedback

  • IPB position is used to

drive the local kicker IPK

  • Latency: 212 ns
  • Effect measured at IPB
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SLIDE 39

Neven Blaskovic Kraljevic 39

Interaction Point Feedback

FB Off Jitter: 412 ± 29 nm FB On Jitter: 389 ± 28 nm Bunch 1

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SLIDE 40

Neven Blaskovic Kraljevic 40

Interaction Point Feedback

FB Off Jitter: 420 ± 30 nm FB On Jitter: 74 ± 5 nm Bunch 2

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SLIDE 41

Neven Blaskovic Kraljevic 41

Interaction Point Feedback

FB Off Correlation: 98.2 ± 0.4 % FB On Correlation: –13 ± 10 %

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SLIDE 42

Neven Blaskovic Kraljevic 42

Outlook

Two IP BPMs can be used to stabilise the beam at a location between them

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SLIDE 43

Conclusions

Neven Blaskovic Kraljevic 43

  • Demonstrated low-latency, high-precision,

intra-train feedback systems

  • Upstream coupled-loop position & angle

feedback stabilises beam locally to 600 nm

  • IP position feedback reduces jitter to 75 nm
  • Future plans involve using 2 IP BPMs to drive

IP feedback

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SLIDE 44

Thank you for your attention!

Neven Blaskovic Kraljevic 44

Many thanks to the FONT team and our ATF colleagues

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SLIDE 45

FONT group

Neven Blaskovic Kraljevic 45

Phil Burrows Colin Perry Glenn Christian Ryan Bodenstein Neven Blaskovic Kraljevic Jack Roberts Davide Gamba Talitha Bromwich Rebecca Ramjiawan Project leader Engineer Lecturer Postdoctoral researchers DPhil students (CERN) DPhil students (Oxford)

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SLIDE 46

Ground Motion vs. Frequency

Neven Blaskovic Kraljevic 46

Vertical ground motion power spectral density integrated up from a range of cut-off frequencies to give the RMS ground motion as a function of frequency

  • R. Amirikas et al., EUROTeV, 2005
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SLIDE 47

Monopole and Dipole Cavity Modes

Neven Blaskovic Kraljevic 47

Monopole mode TMrφz = TM010 Dipole mode TMrφz = TM110 Electric field position independent Electric field proportional to position

  • Y. Inoue et al., PRST-AB, 2008
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SLIDE 48

Neven Blaskovic Kraljevic 48

Upstream Feedback

measured propagated