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Wake field monitors conception, installation and measurements in the CTF3 TBM and TBTS Reidar Lunde Lillestl The University of Oslo / CERN 28. January 2015 1/30 Introduction / Motivation CTF3 Measurements Summary / Outlook Outline 1

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SLIDE 1

Wake field monitors conception, installation and measurements in the CTF3 TBM and TBTS

Reidar Lunde Lillestøl

The University of Oslo / CERN

  • 28. January 2015

1/30

slide-2
SLIDE 2

2/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Outline

1 INTRODUCTION / MOTIVATION

WFMs in CLIC Available modes in the CLIC structure

2 THE CLIC TEST FACILITY 3

The CTF3 and CLEX The Two-Beam Module (TBM) WFM signal connections in the CTF3 WFM scan experimental setup in the TBM

3 MEASUREMENTS

Two-Beam Test Stand (TBTS) measurements First Two-Beam Module (TBM) measurements The PSI electro-optical front-end

4 SUMMARY

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SLIDE 3

3/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Introduction / Motivation

  • In order to achieve the necessary luminosity for

CLIC, we need to preserve a small main beam

  • emittance. L ∝ (ǫxǫy)− 1

2

  • One cause for emittance blow-up can be

transverse wakes in the accelerating structures, which can kick the beam.

  • Dipole wakefields depend on the beam offset from the axis, so we need to

minimize the beam offset in the structures.

  • Wakefield monitors (WFMs) finds the beam

position based on these wakes. Then, alignment of the accelerating structures can be done, and this is foreseen after 1-to-1 steering and DFS.

  • For CLIC, the specification is an alignment of

the accelerating structures of 5 µm.

(Picture is monopole wakefield, not dipole)

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SLIDE 4

4/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

WFM Test stand (see earlier talk this session)

  • N. Galindo

ACS WFM Beam pipe with bellows Hexa- pod Base + active

  • ptical

table

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SLIDE 5

5/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Wakefield monitors in CLIC

  • TD24 accelerating structures: 24

normal cells and 2 matching cells

  • 4 damping slots for each cell
  • 4 bent waveguides with rf absorbers

make up the wakefield monitors.

  • In CTF3, the bent waveguides are

currently installed on the 2nd cell, not the middle one

  • 2 coaxial rf pickups are installed on

different sides of each bent waveguide. One measures TM-like modes, and the other measures TE-like modes.

  • In CTF3, the signals picked up are

measured using log detectors.

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SLIDE 6

6/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Available modes, found with GdfidL

TM-like modes TE-like modes

  • F. Peauger

Slightly different now (2nd cell)

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SLIDE 7

7/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

18 GHz TM dipole mode – electric field map

  • F. Peauger
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SLIDE 8

8/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Outline

1 INTRODUCTION / MOTIVATION

WFMs in CLIC Available modes in the CLIC structure

2 THE CLIC TEST FACILITY 3

The CTF3 and CLEX The Two-Beam Module (TBM) WFM signal connections in the CTF3 WFM scan experimental setup in the TBM

3 MEASUREMENTS

Two-Beam Test Stand (TBTS) measurements First Two-Beam Module (TBM) measurements The PSI electro-optical front-end

4 SUMMARY

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SLIDE 9

9/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

The CLIC Test Facility 3 (CTF3) TBM

1-2× 1-4×

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SLIDE 10

10/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

The Two Beam Test Stand

  • In operation since 2008
  • Many results on
  • two-beam acceleration,
  • rf breakdowns,
  • rf breakdown kicks,
  • PETS recirculation,
  • on/off mechanism,
  • CLIC instrumentation,
  • octupole component of fundamental frequency mode
  • and recently also WFMs
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SLIDE 11

11/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

The remaking of CLEX

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SLIDE 12

12/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

The Two-Beam Module in CTF3

Drive beam

  • 2 PETS
  • 2 Quadrupoles
  • 2 Stripline BPMs

Probe beam

  • 4 Accelerating structures

(2 superstructures)

  • 2 WFMs
  • 4 × 2 × 2 = 16 WFM signals
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SLIDE 13

13/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

WFM signal connections in CTF3

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SLIDE 14

14/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

WFM scan experimental setup

  • Focus beam using quadrupole triplet
  • Use corrector(s) to steer beam
  • Read position on downstream screen (and with BPMs)

C A . Q F D 5 1 C A . Q D D 5 1 5 C A . Q F D 5 2 C A . B P M 5 3 C A . D H / V J 5 4 C A . M T V 5 4 5 C A . B P M 5 6 C A . D H / V J 5 9 C A . A C S 6 4 / 6 5 C A . D H / V J 7 1 C A . B P C 7 2 C A . B P C 7 5 C A . D H / V J 7 5 C A . Q D D 7 6 5 C A . Q F D 7 6 C A . B P M 7 8 C A . M T V 7 9 C A . B H B 8 C A . B P C 8 3 C A . M T V 8 6 CAS.MTV0830 CAS.BPM0820 C A . A C S 6 6 / 6 7 500 500 403 201 246 860 259 1764 1005 1142 213 897 174 300 500 539 466 263 602 488 7464 1071 1339 4383 1307

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SLIDE 15

15/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Outline

1 INTRODUCTION / MOTIVATION

WFMs in CLIC Available modes in the CLIC structure

2 THE CLIC TEST FACILITY 3

The CTF3 and CLEX The Two-Beam Module (TBM) WFM signal connections in the CTF3 WFM scan experimental setup in the TBM

3 MEASUREMENTS

Two-Beam Test Stand (TBTS) measurements First Two-Beam Module (TBM) measurements The PSI electro-optical front-end

4 SUMMARY

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SLIDE 16

16/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

TBTS measurements (i)

Wakefield signals as a function of corrector current (Changing a single corrector)

  • L. Navarro
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SLIDE 17

17/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

TBTS measurements (ii)

WF signals as a function of beam position (Originally position on downstream screen, adjusted to the ACS position) WF signals correlation (Signals in ACS2 vs. signals in ACS1)

  • L. Navarro
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SLIDE 18

18/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

TBTS measurements (iii)

Beam position correlation (a misalignment was found in the horizontal plane) Right: Residuals

  • f the vertical fit

With scaling, the resolution can fulfil the CLIC requirements

  • L. Navarro
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SLIDE 19

19/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

First results in TBM: Delta signals at ∼18 GHz

2000 2200 2400 2600 2800 3000 −0.05 0.05 0.1 0.15 0.2 Time [ps] ∆H signal 1500 2000 2500 3000 −6 −4 −2 2 4 6 8 x 10

−3

Time [ps] ∆V signal 2000 2200 2400 2600 2800 3000 −0.1 0.1 0.2 0.3 0.4 0.5 0.6 Time [ps] ∆H signal 2000 2200 2400 2600 2800 3000 −0.05 0.05 0.1 0.15 0.2 0.25 0.3 Time [ps] ∆V signal

Beam LEFT Beam LEFT Beam TOP RIGHT Beam TOP RIGHT

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SLIDE 20

20/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Delta signals over sum signals, vs. position (all at ∼18 GHz)

−1.5 −1 −0.5 0.5 1 0.5 1 1.5 2 2.5 3 Beam position in X [mm] ∆H / ΣH −1 −0.5 0.5 1 1.5 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 Beam position in Y [mm] ∆H / ΣH −1.5 −1 −0.5 0.5 1 1.5 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 Beam position in X [mm] ∆V / ΣV −1 −0.5 0.5 1 1.5 0.5 1 1.5 2 2.5 Beam position in Y [mm] ∆V / ΣV

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SLIDE 21

21/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Single antenna signals (∼24 GHz)

2000 4000 6000 8000 10000 −0.08 −0.07 −0.06 −0.05 −0.04 −0.03 −0.02 −0.01 0.01 Time [ps] ’Up’ signals 2000 2200 2400 2600 2800 3000 −0.03 −0.02 −0.01 0.01 0.02 0.03 0.04 0.05 0.06 Time [ps] ’Left’ signals 2000 2200 2400 2600 2800 3000 −0.05 0.05 0.1 0.15 Time [ps] ’Up’ signals 2000 2200 2400 2600 2800 3000 −0.04 −0.02 0.02 0.04 0.06 0.08 Time [ps] ’Left’ signals

Beam FAR LEFT Beam FAR LEFT Beam TOP RIGHT Beam TOP RIGHT

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SLIDE 22

22/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Background issues (∼24 GHz)

Possible peak detected as zero, because of the strange looking background signal! (Background somewhat different between datasets, so it is challenging to subtract)

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SLIDE 23

23/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Drive beam noise in WFM signals

200 400 600 800 1000 0.5 1 1.5 2 2.5 Time [ns] ’Left’ antenna signal (treated) 200 400 600 800 1000 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Time [ns] ∆H signal (treated)

Drive beam in TBM Drive beam in Test Beam Line (timing wrong) Proper WFM signal –

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SLIDE 24

24/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

The PSI electro-optical front-end

  • New WFM front-end, based on an

electro-optical approach

  • Radiation hardness well understood, can carry

signals with negligible EM interference

  • Use of Electro-Optical Modulators, that via

the applied electric fields change the phase delay of light paths in a LiNbO3 crystal and enables QAM modulation

  • Possible testing in the TBM this year
  • M. Dehler
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SLIDE 25

25/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Summary and Outlook

Summary

  • CLIC WFMs use two dipole modes for beam position measurements
  • Measurements in TBTS gave a good resolution and revealed a horizontal ACS

misalignment

  • First measurements done in the TBM. However, some issues with background

(especially from the drive beam) Outlook

  • March/April: Restart measurements in TBM
  • Presently a large amount of DB noise – should be improved (shielding etc.)
  • Collaboration with M. Dehler (PSI), investigate the use of an electro-optical

front-end, possibly testing it in CTF3

  • Possible front-end collaboration with the electronics lab in the University of Oslo
  • Use Ace3P/Cubit for WFM simulations, revisit design

Thank you for your attention!

Special thanks to Wilfrid Farabolini, Luis Navarro, Natalia Galindo, Nuria Catalan, Micha Dehler, Roberto Corsini, Alexej Grudiev, Erik Adli, J¨ urgen Pfingstner, Danish Nawaz, Davide Gamba, Roger Ruber and Steffen D¨

  • bert
slide-26
SLIDE 26

25/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Summary and Outlook

Summary

  • CLIC WFMs use two dipole modes for beam position measurements
  • Measurements in TBTS gave a good resolution and revealed a horizontal ACS

misalignment

  • First measurements done in the TBM. However, some issues with background

(especially from the drive beam) Outlook

  • March/April: Restart measurements in TBM
  • Presently a large amount of DB noise – should be improved (shielding etc.)
  • Collaboration with M. Dehler (PSI), investigate the use of an electro-optical

front-end, possibly testing it in CTF3

  • Possible front-end collaboration with the electronics lab in the University of Oslo
  • Use Ace3P/Cubit for WFM simulations, revisit design

Thank you for your attention!

Special thanks to Wilfrid Farabolini, Luis Navarro, Natalia Galindo, Nuria Catalan, Micha Dehler, Roberto Corsini, Alexej Grudiev, Erik Adli, J¨ urgen Pfingstner, Danish Nawaz, Davide Gamba, Roger Ruber and Steffen D¨

  • bert
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SLIDE 27

Extra slides

26/30

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SLIDE 28

27/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

TBM schematic

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SLIDE 29

28/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

CLIC WFM S-parameters

  • F. Peauger
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SLIDE 30

29/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

First WFM scan in the TBTS

  • F. Peauger,
  • W. Farabolini
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SLIDE 31

30/30 Introduction / Motivation CTF3 Measurements Summary / Outlook

Electro-optical front-end: Structure tilt

3 positions in the structure show different minima during a tilt of the structure

  • M. Dehler