CALIFES-Based Beam Facility

1

CALIFES-Based Beam Facility

W. FaraboliniK. Yaqub

W. Farabolini - CLIC Workshop 2014

W. Farabolini - CLIC Workshop 2014 2

Contents

• CALIFES today• Present uses of CALIFES

– Beam test of the accelerating structure– Beam Instrumentation tests

• Possible evolutions


CTF2/CTF3 overview

Dog-leg experiment

Stand-alone test standPHIN gun


Convenient hall (42 x 8 x 2.6 m3) with proper concrete shielding (2.8 m) and large access.

Electronic gallery just above with many communication holes

An up-to-date Laser lab, but a little bit far (80 m laser beam line, partly under vacuum)

Fully equipped (conditioned air, water, access control… (except crane))

CLEX experimental hall

8 m

TBLDBPB

42 m

http://ctf3-tbts.web.cern.ch/ctf3-tbts/images/CLEX-hauteur_faisceau.jpg









CALIFES today

F. Peauger et al., Proceedings of LINAC08, Victoria, BC, Canada

A Photo-injector

3 LIL accelerating structures

A single 3 GHz klystron with BOC pulse compression

2 power phase shifters (gun and first structure)

1 attenuator (gun)

A complete set of beam diagnostics


CALIFES Performances

Parameters Specified Tested CommentEnergy 200 MeV 205 MeV Without bunch compressionNorm. emittance < 20 p mm.mrad 4 p mm.mrad With reduced bunch chargeEnergy spread < ± 2 % ± 0.5 %Bunch charge 0.6 nC 0.65 nC With new photocathodeBunch spacing 0.667 ns 0.667 ns Laser drivenNb of bunches 1-32-226 from 1 to 300 Limited by RF pulse lengthrms. bunch length < 0.75 ps 1.4 ps ?? Still to be checkedRepetition rate 0.8 – 5 Hz 0.8 – 5 Hz Upgrade possibility to 10 Hz

A very easy to operated LINAC (by users themselves)


The Two-Beam Test stand

PB

DB

Presently

And after CLIC module installation (June 2014)Dmitry Gudkov


Extensively instrumented test stand

2 phase shifters 1 variable splitter

15 RF channels(Diodes and IQ)

2 screens 1 Flash box

Thermal probes and flow rate

3 PMTs16 WFMs channels

1 FCU


Test of 12 GHz accelerating structures performances

Califes beam on the final spectrometer

RF Off

RF On

Energy gain for various RF phases

Phase scan

Power fluctuations

ESSENTIAL PERFORMANCE VALIDATED for CLIC

Require to master: timing and phase between beams, phase between structures, power and phase measurement accuracy, energy measurement accuracy.


Beam kick during Breakdown

On YAG screen without BD

With BD

Beam before BD

Beam after BD

Time resolved position on cavity BPM

0.68

mm

A. Palaia PhD Thesis

EXPERIMENTS WORTH to be CONTINUED with much more statistics

Results in accordance with SLAC measures


Why it is so important for CLIC ?Example exercise:• Most restrictive structure: Collimators (200 μm opening of spoilers).• Potential damage: Destruction of spoilers

– In the present design spoilers are consumables: 1 hit – you're out!– If we can use spare surface (8mm), fully consumed after 1 – 10?? impacts (depending

on the severity).

• Derive maximum kicks, displacements, transverse RF in the Main Linac corresponding to 100 μm.

• Note: to kick any of the other sensitive structures (accelerator structures, vacuum chamber) the required kicks are 2 orders of magnitude larger!

E [GeV] β [m] Max Kick H-app equiv. Max Vtransverse

Entry Main Linac 9 1.8/7 22 μrad 155 μm 200 keV

Exit Main Linac 1500 18/67 0.56 μrad 37 μm 830 keV

M. Jonker

•However, in addition to a dipole kicks, a break down may also contain higher order modes, leading to a blow-up of the beam (which is beneficial).

12

Wakefield Monitors studies

0.12 mm Without RF power

With RF power


F. Peauger

EXPERIMENT to be RESUMED during next Run with nominal RF Power

ACS with WFM

Position scan with corrector

• Already promising results (misalignment between the 2 ACS detected and corrected) • Electronics completed recently• Performances at nominal power still to be assessed


Why it is so important for CLIC ?D. SchulteImpact of Wakemonitors

Single machine shownWith no wakemonitorsWith wakemonitors

Goal is to keep emittance growth due to wakefields below 1nm• Average emittance growth with no wakemonitor is about 40nm

• Sensitive to prealignment, girder accuracy, structure accuracy etc.• With wakemonitor we find about 0.5nm

• Only sensitive to accuracy of structure and on electronics


Octupolar field study

For very weak RF power (few MWs, uncertain phase)

At zero-crossing (rising RF power side), 25 MW

At zero-crossing (falling RF power side), 25 MW

Ray-tracing model through octupolar fields

“Multipoles of the accelerating field and the beam distortion in TBTS”, Alexej Grudiev, 29/05/2013 CLIC RF Structure Development Meeting

EXPERIMENT to be RESUMED during next Run with well calibrated power to benchmark the Panofsky-Wenzel and Lorentz force models


Beam profiles studies

“Measurement of transverse coupling in the TBTS, Christopher Borgmann, 22. October 2013, CLIC/CTF3 Exp. Verification meeting”

EXPERIMENT to be RESUMED during next Run


CALIFES used for testing beam diagnostics


EOS for bunch length measurement

Rui Pan (PhD student), Electro-0ptical Bunch Profile Measurement at CTF3 IPAC’13 MOPME077.

Inside CLEX optical tables for laser beam injection

Electron bunch synchronous with laser pulse


Test of high resolution BPMs

Cavity BPM installed on CALIFES line

F. Cullinan (PhD student), J. Towner A Prototype Cavity Beam Position Monitor for the CLIC Main Beam, IBIC'12 MOPA18

Position and beam charge linearity


Why it is so important for CLIC ?

T. LefevreMain Beam Cavity BPM • High luminosity foreseen for CLIC requires small

beam size at the IP (nm regime) -> low emittance beam transport throughout the linac

• Dispersion free steering minimizes emittance growth.Concept:

– Apply an energy chirp along the beam pulse– Dispersive effects can be detected within the same beam

pulse, independent from jitter, starting conditions, etc.

• BPM requirements:– High spatial and temporal resolution simultaneously!– 50 nm spatial resolution requirement.– 50 ns requirement to make 2-3 position measurements

within the 156 ns long bunch train.

• Ultimate goal is demonstrate the combined spatial and temporal resolutions using a system of 3 BPMs in CTF3.

• CALIFES is essential for this, as it can deliver beam with CLIC-like parameters.

20

Test of beam loss monitorsElectro-optic bunch profile monitor in CALIFES(CERN-Dundee University)


Sophie Mallows(PhD student), A fiber Based BLM System Research and Development at CERN, HB2012 THO3C05

F. Burkart, O. Stein,E. Nebot Del Busto

Diamond beam loss detectors


Why it is so important for CLIC ?Quantity of LC Beam Instruments

BI Type ILC-nom (RDR) CLIC-3-DB CLIC-3-MB

Intensity 40 278 184

Position 4478 46054 7187

Size 142 800 148

Energy (spread) 13 (13) 210 (210) 73 (23)

Bunch length 13 312 75

Beam loss / halo 1440 45950 7790

Beam phase 14 208 96

Polarization ? 17

Tune 4 6

Luminosity 2(?) 2

• Impressive quantities!– Calls for well though through engineering and optimization

M. Wendt

22

CALIFES: a very flexible beam


Streak camera measurements : =s 6.5 ps, S. Mazzoni

1, 2, 3… bunches with transverse space separation

Very small beam size 37 x 33 mm

Califes Swiss FEL from Simona


Califes for BI testThibaut Proposal


Califes for BI test- ‘’TéPaFou’ - A Beam Instrumentation Test Facility at CERN for CLIC but also for

existing and future accelerators- with the present CERN accelerator schedule, every 3 years, we have 1-2 years

long shutdown with no testing capabilities

- Electron linac is the cheapest way to provide relativistic beams- Beam energy : more than 150MeV

- Wish list for Beam parameters- Short and long bunches (100fs up to 200ps)- Large range of beam/bunch intensity- Possibility to study time to position correlation (Crabbing)

- Photo-injector is a best way to provide a modular bunch spacing- Single bunch capability- Possibly bunch spacing similar to CERN beams (1ns, 5ns, 25ns, 50ns, .. )- Pump – probe experiment (wakefield study, impedance measurement, ..)


Califes for BI test

Magnetic chicaneShorten or lenghthen

RF deflectorfor crabbing

CollimatorReducing the bunch intensity

Machine layout to cover BI needs based on CALIFES

Beam current monitor Beam position monitor Beam profile monitor

Short and long bunches (100fs up to 200ps)

Large range of Bunch intensity

Time to position correlation


Califes for BI test

Synchrotron radiation test stand

In-air DUT area

Synchrotron radiation test stand

Under vacuum DUT area

Machine layout to cover BI needs based on CALIFES

• Including SR test stand for infrared, visible and UV light: Several port available• Including Testing area for beam instruments – Under Vacuum DUT• Including Testing area for particle detectors – In air DUT – low intensity option


Califes for BI instrument testSynchrotron radiation source- Testing optical detectors with short photon probes over a wide range of wavelength (IR, visible, UV)- Possible use for developing

- Beam halo monitor, longitudinal density monitor, …

In-air DUT area- Possibility to decrease the beam intensity to low or very low values- Possible use for developing Beam Loss monitors and Particle detectors

Study of MIP response, Time response study, Signal saturation studies, Space charge studies, Dose damage

Under vacuum DUT area- Independent vacuum zone with easy access and pumping capabilities- Including steering magnets to move the beam around- Equipped with a Permanent instrumentation test stand

- Used for beam cross calibration: beam size, position and bunch length- But also using ...

- BTV station for screen and imaging system development- Pick-up for providing fast EM signal for testing electronic acquisition system- Coherent diffraction slit as a source for GHz-THz

- Possible use for developing- Beam position monitor, Wall current monitor, fast beam transformer, Ionization gas monitor, Wire

scanner…


Possible evolutions of CLEX

• Keep Califes alone for beam instrumentation test– Add an available S-band klystron– Add a chicane– Switch for the PHIN gun

• Push the beam line toward the X-Box1 in CTF2• Or transport the 12 GHz power to CLEX

– Add an undulator, a Compton scattering experiment…– Add a 12 GHz crab cavity for bunch length diagnostic

• Produce special beam for Wakefield study – 2 bunches of different energies with adjustable delay


An additional klystron for CALIFES

Present Klystron

BOC

Cradle for 2nd

klystron

Higher flexibility in :

- Energy from 50 to 250 MeV

- Pulse length > 200 ns

- Bunch compression

- Beam loading compensation

- Beam repetition rate (> 10 Hz)

- Worth to upgrade C/C and data acquisition


Instrumentation line with chicane

• A preliminary study has been done: “Short Pulse Capabilities of the Instrumentation Beam Line – V. Ziemann – 6 May 2010”

- Short pulses (200 fs – 35mm) are necessary to mimic the CLIC main beam for instrumentation tests

- Pulses of 20 mm are achievable with a chicane R56 = 2 cm and energy encoding of 10-

3 , maximum energy reduced to 78% of the on crest one• All equipments will be available from the DB lines (magnets, powers, chambers…)


Switch for PHIN gun

Higher bunch charge (~ 1 nC) (photo-cathodes with higher QE)

Longer pulse length (> 1.5 ms) (if a second klystron installed)

Lower emitance at high bunch charge

Possibility to use the present CALIFES gun for the AWAKE experiment

PHIN gun and its spectrometer line


CALIFES beam to CTF24.

7 m

26.5 m 42 m

8 mStand Alone

Test Stand

Preserve the accelerating structure test facility with beam capability

Possibility to operate up to 4 ACS at 65 MV/m (300 MeV beam)

Possibility to add a wriggler to make a FEL (laser lab just above)

Possibility to develop a Compton scattering facility

Possibility to use a 12 GHz crab cavity for bunch length diagnostic

Narrow access in CTF2

Weaker concrete shielding (to be reinforced)


X-Box1 RF power to CLEX4.

7 m

26.5 m 42 m

8 mStand Alone

Test Stand

Low loss circular waveguide

Use of the existing diagnostics around the TBTS

CLEX hall well fitted for experiments

Limited beam line available: 15 m (except U turn)

Less flexibility for diagnostics tests


Use of CALIFES for Wakefield tests

70 o phase acceptance

65 ps

Laser with photo-injector offers great flexibility (as proven by phase coding)

Objective: to generate 2 successive bunches at different energies and with variable spacing. (ex. using 2 pulse picker units and an optical delay line)

Interesting challenge for the laserists

Gun bunch charge as function of phase

3 GHz Accelerating field

First bunch

second bunch

N x 333 + variable delay(0-65) ps


Summary of some possibilitiesDiagnostic test facility See this WS:

Add a new klystron

Add a chicane

Use PHIN gun

X-band test facility

X-Box1 RF power to CLEX

Beam to CTF2

Upgrade modulator and beam diag. to 50 HzAdd a X band deflecting cavity

X-band demonstrator

4 ACS @ 85 MV/m

FEL Alexej GRUDIEVCompton Scattering

Neutron Facility Mitsuru UESAKA Medical Facility Stefano BENEDETTI Exotic non linear optic machine (IOTA type)

Wakefield test facility


Oslo Interest

E. Adli: We got approved a significant amount of money in Oslo for further CLIC/CTF3 work (very good news!), and we plan to work further with design and tests of Wake Field Monitors, and Califes is the natural test-bed.

Oslo group: plans 2014-2017• The University of Oslo (Erik Adli) has established a

project for further investigating linear collider nm emittance preservation, both by simulation/algorithm testing at FACET/ATF2 and by experimental tests of Wake Field Monitors (WFM)

• Funding is secured: 1 – 1.5 MEURO, 2-3 researchers and PhD students, rf electronics

• Timescale: ~Mid-2014 – ~Mid-2017• One of the key challenge is demonstrate WFM as a

reliable means to ensure CLIC main linac emittance preservation (Deny of 10 nm)

• A crucial test is to prove experimentally that the required WFM beam position resolution of ~3 um can be achieved in a realistic test environment

F. Peauger et al. "Wakefield monitor development for CLIC accelerating structure", Proceedings of LINAC'10 (2010)

Oslo: need for test facilities• Realistic conditions: the Wake Field Monitors performance must be tested with both beam

and X-band rf power corresponding to the accelerating gradient of CLIC• Only place we are aware of where this can be done: CTF3, in the Califes beamline. Using the

CTF3 drive beam generation, tests could be performed with X-band from the TBTS. Later X-band power can be provided by XBox 1.

• Testing of the final version of design will typically come only towards the end of the project. I.e. we have a need for a test-bed with an e-beam and 70 MW X-band power until 2017 -> Califes is the only candidate we see that could be available in the project period for the WFM development.


Conclusions• CALIFES has proven its value for studying and

qualifying the novel accelerating structures,• In addition, CALIFES has gain a growing

interest from the beam diagnostic community,• Keeping CALIFES in operation is cost effective,• Simple upgrades will offer even more

opportunities to progress in Lepton accelerators Science and Technology.

A big thanks to all the colleagues who have contributed with enthusiasm to this presentation by sending me material .

Documents

CALIFES-Based Beam Facility