The future of CTF3

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R. Corsini – The future of CTF3, 30/1/2015 CLIC Workshop 2015
The future of CTF3
R. Corsini
4/3/2015

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DRIVE BEAM
LINAC
COMBINER
RING
CLIC Test Facility (CTF3)
DELAY
LOOP
CLEX
TBL
4/3/2015
Two Beam
Module

3
4/3/2015
High current, full
beam-loading
operation
Operation of
isochronous lines
and rings
Bunch phase coding
Beam recombination &
current multiplication by
RF deflectors
12 GHz power
generation by drive
beam deceleration
High-gradient
two-beam acceleration
PETS ON/OFF
4 A, 1.4us
120 MeV
30 A, 140 ns
120 MeV
30 A, 140 ns
60 MeV
CLIC Test Facility (CTF3)

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4/3/2015
The next two years…
TBL
deceleration
Two Beam Module,
Wake-field monitors…
Dogleg Beam
loading
experiment
Phase feed-forward
experiment
Diagnostics R&D
using CALIFES

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4/3/2015
CLIC system tests beyond
CTF3
• Drive beam R&D beyond CTF3
• RF unit prototype with industry using
CLIC frequency and parameters
• Drive beam front-end (injector), to
allow development into larger drive
beam facility beyond 2018
• Damping rings
• Tests at existing damping rings,
critical component development
(e.g. wigglers) ... large common
interests with light source
laboratories
• Main beam
• Beam based alignment tests at
FACET, FERMI, …
• Beam Delivery System
• ATF/ATF2
§ Super-conduc ng wigglers
§ Demanding magnet technology combined
with cryogenics and high heat load from
synchrotron radia on (absorp on)
§ High frequency RF system
§ 1 GHz RF system respec ng power and
transient beam
§ Coa ngs, chamber design and ultra-
low vacuum
§ Electron cloud mi ga on, low-
impedance, fast-ion instability
§ Kicker technology
§ Extracted beam stability
§ Diagnos cs for low emi ance
Experimental program set-up for
measurements in storage rings and
test facili es:
ALBA (Spain), ANKA (Germany),
ATF (Japan), CESRTA (USA),
ALS (Australia) …
Parameters BINP CERN/Karlsruhe
Bpeak [T] 2.5 2.8
λW [mm] 50 40
Beam aperture full gap [mm] 13 13
Conductor type NbTi NbSn3
Operating temperature [K] 4.2 4.2
Gun SHB
1-2-3
PB Buncher Acc. Structures
500 MHz
Modulator-klystrons, 1 GHz, 20 MW
~ 140 keV ~ 12 MeV
Diagnostics
~ 3 MeV
S. Stapnes

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Context
• CTF3 went well beyond its initial task of demonstrating CLIC two-
beam scheme feasibility
• Has a well established scientific program until end 2016
• Definitely want to stop CTF3 after that (limited resources…)
 What to do with CTF3 hardware & building?
• Discussions started beginning 2014. Current main proposals:
 Install new DB front-end in CTF3 linac area (CLIC related).
 Keep using CALIFES linac in CLEX for as a general test facility after
2016. Possibly interesting beyond CLIC scope (in CERN and outside).
 Last discussions at LCWS 2014 – Belgrade & CLIC Project Meeting:
https://agenda.linearcollider.org/event/6389/session/18/#20141009
http://indico.cern.ch/event/356495/
4/3/2015

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Rationale for uses of CTF3 hardware beyond 2016
4/3/2015
• CLIC Collaboration interest: keep beam test capability for CLIC (diagnostics,
components…) locally at CERN after CTF3 stop
• Some additional points:
• Possibility of beam tests during long shut-downs
• Keep experimental electron expertise alive at CERN, including laser and photo-
cathodes – link with AWAKE
• Complement high-gradient X-band activities for X-FELs, medical…
• Provide training ground for young accelerator physicists at CERN and
collaborating institutes
 Find synergies with other potential partners (project/groups within and outside CERN)
in order to gather enough resources and get approval from CERN management

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Tuesday session on Future tests beyond CTF3:
Scope and aim
4/3/2015
• Concentrate mainly on CALIFES
based proposals
• Review proposals and identify
needs (basic and advanced),
both in terms of beam parameters
and for
operation/hardware/infrastructure
• Try to define a list of beam
parameters and of
space/hardware requirements
capable to satisfy most of the
users
• Discuss and if possible decide on
next steps needed to arrive at a
proposal

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Drive Beam Front-End
4/3/2015
• Same peak current than
present CTF3 injector (4 A)
• Longer pulse (140 us
instead of 1.4 us)
• Higher rep rate possible
(up to 50 Hz)
Option: keep operational also
(part of) the present 3 GHz linac.
Will enable beam energies up to
~ 100 MeV with limited pulse
length( ~ 4 us max).
The drive beam front-end in the
CTF3 building – F. Tecker, LCWS2014
http://agenda.linearcollider.org/event/6389/sessi
on/18/contribution/114/material/slides/0.pptx

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Beam Loading experiment - run beyond 2016?
Drive beam, 1-3A,
100-50 MeV
 50 mm
circular
waveguide
RF
• Before 2016 ~ 3 test slots (one per year) – not a large
statistics
• In this time scale could have a new CLIC structure
prototype from re-baselining, may want to test it
• Want to explore structures with different (tapered-
up) gradient profile
• Other potential users?
• Need relative small part of infrastructure – 5 MKS,
first 50 m of linac / Compatibility with Front-end?
4/3/2015
T24 structure
installed in CTF3
From XBOX-
1
CLEX
LINAC
DELAY
LOOP
COMBINER
RING
BL - BDR
experiment
Unloaded
Loaded (CLIC)
Increasingcurrent
Gradient along the structure
Average gradient
100 MV/m

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Former CTF2 area, X-band and S-band RF testing
4/3/2015
• X-band test area, connected to XBOX1
• Used also for 3 GHz structure and component
testing (TERA, ADAM…)
• XBOX1 will stay, keep using the area also for 3 GHz
• Compatible with other options

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CALIFES
4/3/2015

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CALIFES Beam parameters
• 0.01-1.5 nC bunches, 1.5 (3) GHz spacing (0.667 ns/0.333 ns)
• From single bunch to 200 ns train
• Rep rate 1-10 Hz
• Energy 150 - 200 MeV
• Normalized emittance 4 mm
• Energy spread ± 0.5 %
• Bunch length 1-2 ps and above
• May provide lower energy (>10 MeV), need to study transport
• Typical beam sizes 0.25 × 0.25 mm, uniform beam sizes obtained up
to now 5 mm × 5 mm, up to few cm surely feasible.
4/3/2015

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Potential interests for CALIFES based test facility
4/3/2015
• Diagnostics R&D with beam tests
(for CLIC, LHC & injectors, AWAKE…)
• X-band structure testing with beam
(X-FEL, medical applications, wake-field
monitors, deflecting cavities…)
• Impedance and wake-field
measurements of components
(LHC, CERN Injectors, HL-LHC, CLIC…
for Cavities, diagnostics equipment,
collimators, kickers…)
• Irradiation tests (ESA/JUICE Mission, CERN
and others…)
• Plasma wake-field acceleration
• Beam tests of hardware (kickers, SC RF
cavities)
• Other medical applications (X-ray imaging,
therapy with e-, isotopes production…)
• Test beam for detectors
• Vacuum related tests
• …

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o Machine operation schedule @ CERN
o Long periods without the capability of performing beam tests
o Limited beam time available for Machine Developments combined with a high
number of requests
o Hardware installation periods are limited
o Any further improvements/modifications can not be implemented quickly
o Testing at Independent Facility will faster the developments and ensure that
we installed well-understood devices on operation machine
o Developing new concept versus Reliable operation
o Operational machine have strict requirements in terms of vacuum-outgassing
performance/ bakeability not always compatible with R&D needs
o e.g. Testing gas ionization monitor and their performance as function of gas
pressure
T. Lefevre
CALIFES for diagnostics R&D - Why

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o CERN accelerators
o LHC, HL-LHC, LIU (SPS, PS, PSB) projects
o CLIC/ILC, AWAKE, FCC studies
o Future Challenges in Beam Instrumentation
o Unprecedented request for precision
o Positioning down to below the micron level
o Treatment of increasingly more data
o Bunch by bunch measurements for all parameters:: Test of state of the art
acquisition system (electric or optical domain)
o Dealing with high beam powers
o Non-invasive measurement techniques (Gas profile monitor, Quadrupolar PU,
..)
o Robust and reliable machine protection and beam loss monitoring systems
o Dealing with the (ultra) fast
o Sub-picosecond bunch lengths in AWAKE and CLIC
o Longitudinal tomography in LHC (picosecond range)
o Fast transverse beam position monitors (HL-LHC Crab cavities and transverse
beam Instability diagnostics)
What for
T. Lefevre

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o A Test facility can not address all specific issues. But ….
o System performance under realistic conditions that are not easily
achievable in laboratory
o Test with realistic signals state of the art electronic
o i.e. Response to short pulses with high signal amplitude
o Test of UV, optical, X-ray monitors where no other source can reproduce beam
induced radiation
o Imaging technique and Beam halo monitoring
o Use of electro-optical crystal
o Validation of particle detector design (e.g. Beam loss monitor/ Luminosity monitor)
o Sensitivity checks, linearity (or non-linearity) checks, ..
o Study the behavior of devices with respect to beam position / bunch
length / bunch intensity variations
What for
T. Lefevre

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o Electron linac is the cheapest way to provide relativistic beams
o Beam energy higher than 200MeV (3.5GeV max) – similar g as on SPS (LHC)
o Photo-injector provides a modular bunch spacing
o Single bunch capability
o Bunch spacing similar to CERN beams (1ns, 5ns, 25ns, 50ns, .. )
o Pump – probe experiment (wake-field study, impedance measurement, ..)
o Simplicity, Reliability and Flexibility
o Wish list for Beam parameters
o Good emittance to reach small beam size (<50um)
o Short and long bunches (100fs up to 200ps)
o Large range of bunch intensity
o Possibility to study time to position correlation (Crabbing)
Slightly modified version of CALIFES
o Applications requiring high beam current would require Drive Beam
Injector (Beam heating studies, ..)
How T. Lefevre

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Future CALIFES – minimum configuration
4/3/2015
• Add an available S-band klystron + modulator
• More RF power (beam energy), more flexibility (power in 1st structure, phase in
structures 2 and 3), possibility of running without RF pulse compression
• Reconfigure present TBM area as test area
• Most (all) hardware already existing
Future: CALIFES for beam instrumentation test
Test Area
Spectrometer
Present
Perspectives for a CALIFES test facility
beyond 2016 – R. Corsini, LCWS2014
http://agenda.linearcollider.org/event/6389/session/18/
contribution/115/material/slides/0.pptx

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“Ultimate” test area layout to cover BI needs
4/3/2015
Magnetic chicane
Shorten or lenghthen
100fs up to 200ps
RF deflector
for crabbing
Time to position correlation
- Reduce the bunch intensity
before the DUT zones
- Reduce bunch length further in
combination with RF deflector
Collimator
T. Lefevre
Synchrotron radiation test stand
Synchrotron radiation
test stand
Under vacuum
DUT area
DUT: Device under Test

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Irradiation testing with CALIFES
4/3/2015
M. Brugger,
R. Garcia Alia

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Impedance measurements - Context
• Impedance team involved in design and approval of new and
modified equipment in all CERN circular machines (in particular
PSB, PS, SPS and LHC, but also AD, ELENA and CLIC damping
rings).
• Tools at our disposal:
• Bench measurements with wires and probes
 problem: not direct measurement of
impedance or wake, and possibly strong
perturbation of the EM fields
• Numerical simulations
 problem: difficulty to reproduce reality with
a model (e.g. design errors, small features,
coatings, matching errors) , simulated exciting
bunch is not a delta function.
 Measurement with electron bunches could be an interesting complement to these existing tools
B. Salvant - CERN

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 Simple measurement, would not need any additional hardware
 Requires pre installation of a probe in the device (if there is not already one).
 Switch from ferrite damping to coupler damping is proposed to avoid beam induced heating
Source bunch
RF pickup
Direct measurement of generated electromagnetic fields
• Possibility to measure EM fields from available
antennas, buttons, striplines, wires, all mode couplers
already in the device (or installed just for that reason).
 See also proposal of electro optical pickup
• Indirect measurement in principle, but possibility of direct benchmark of
CST Particle Studio simulations with fields monitors and check their validity
 probe measurements only validate the Qs from eigenmode simulations
 wire measurements can perturb significantly the modes.
 real interest in using an electron source
• For the case of the wirescanners for instance, possibility to directly measure the signals
that we need
 current induced by the beam  beam induced heating
 would be very important, and the only direct way of measuring the heat load to the wire
(besides installing it in the SPS or the LHC).
• For other devices, it would be an indirect measurement that could validate the model,
meshing and simulation.
B. Salvant - CERN

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Electro-optic Diagnostics for Wake-field Characterisation
4/3/2015
S. Jamison
ASTeC - Daresbury National Lab
CALIFES EO Test

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EO measurement of wake fields in
Swiss Injector test facility
4/3/2015
S. Jamison
ASTeC - Daresbury National Lab

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Direct measurement of “wake function”
• Measurement of energy loss as a function
of source/test bunch spacing 
longitudinal wake
• Measurement of kick as a function of
source/test bunch spacing 
transverse wake
• In simulations, difficult to reach source
bunch below 1 mm for standard devices
due to mesh size.
• Very small bunch length achievable with
electron beams (2 to 3 ps in CALIFES)
 “wake function” could be measured
provided the sampling is sufficient.
Feasible?
Test bunch Source bunch
Bunch spacing
Test bunchSource bunch
B. Salvant - CERN

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Direct measurement of “wake function”
• Important to disentangle the “dipolar” impedance contribution from the
“quadrupolar” contribution to assess the impact on collective effects
Bunch spacing
xsource=dxtest=0
Bunch spacing
xsource=0xtest=d
Driving impedance contribution Detuning impedance contribution
 All particles in the test bunch receive the same
kick
 Coherent effect
 Drives instabilities
 All particles in the test bunch receive a kick
proportional to their position
 Incoherent effect
 Impact on instability depends on the type of
instability
 Can the orbits of the source and test bunches be controlled separately?
B. Salvant - CERN

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Example: LHC crab cavities
Driving impedance
(also called
dipolar impedance)
Detuning impedance
(also called quadrupolar
impedance)
 Very different features between driving and detuning impedance and very different effects.
 Detuning impedance generally small for cylindrically symmetric structures
 Detuning impedance is very significant for SPS kickers (for instance) and tricky to obtain from wire measurements
 Need to control separately source and test bunches
Wake potential Impedance
B. Salvant - CERN

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Potential limitations
- Minimum kick strength observable with the BPM resolution
 Many components are in the 1 to 10 kOhm/m range for the transverse impedance, in the mOhm range for
the longitudinal impedance
 Previous studies show that the kick is of the order of 10 microns after 1 m for 10 kOhm/m
 Roberto Corsini proposed possibilities to amplify this kick using lever arms
 This could require 3 BPMs before the device and 3 BPMs after the device (H. Schmickler)
 Reducing the energy of the test bunch would help!
- Need to disentangle between the test and source bunch
 Can we resolve 0.1 ns between two bunches? Challenging together with resolution requirements
 Would need special BPM development
 Could a high bandwidth kicker be used (prototype installed in SPS to work in GHz range)?
- Accurate control of the orbit and spacing of test vs source
 difficult to do with one electron source, contrary to FACET
 ideas to delay the bunch, delay the laser pulse to control the spacing
 ideas to move the laser pulse transverse position to control independently the transverse position
 this could be the main limitation for the setup
- Control of intensity of both bunches (highest on source and low on test)
- Available length (for both device installation and for observation)
 some critical elements are very long (SPS septa, LHC TDI and kickers).
- Need for large flexibility in length and radius of input device
 the facility may become a tapering factory.
- Contribution from the BPMs and tapers should not dominate (from 40 mm/20 mm radius to the aperture of the element)
B. Salvant - CERN

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Table of “ideal” requirements (draft, for discussion)
Direct
measurement
Wake function reconstruction
Intensity of the source bunch ~1 nC ~1 nC
Intensity of the test bunch - Not critical
Number of bunches - At least 2 bunches
Minimum bunch spacing - 0.1 ns – 0.3 ns
Maximum bunch spacing - 25 ns – 1 ms
Sampling in bunch spacing - 0.1 ns within the first 5 ns, 0.3 ns
after the first 5 ns
BPM resolution (time) - 0.1 ns - 0.3 ns
BPM resolution (position) 1 micron
Source bunch energy - 200 MeV
Test bunch energy - Would help if lower than 200 MeV
Available installation length 1.5 m for devices
+ 1 m for taper
= at least 2.5 m
At least 2.5 m
B. Salvant - CERN

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Beam driven PWFA
Beam driven PWFA:
Two-bunch acceleration. A
drive bunch drives a plasma
wake, being decelerated. A
witness bunch extract the
wake energy, being
accelerated.
PWFA has potential for:
- High gradient (>10 GV/m)
- High efficiency (>50%)
- Low energy spread (<1%)
- High charge (~nC)
- Emittance preservation
Above: PIC simulation based on example
parameters from the PWFA-LC design study.
Not discussed here: laser driven plasma
wakefield acceleration.
PIC simulations performed with the code
QuickPIC (W. An, W. Mori, UCLA)
E. Adli – Oslo University

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Experimental progress in PWFA
High gradient (~50 GV/m) demonstrated
several years ago; SLAC linac energy doubling
of beam tail.
Acceleration of a witness beam, with
high efficiency (>30% wake to beam),
high gradient (5 GV/m) and low energy
spread (~1%) recently demonstrated at
SLAC/FACET.
M. Litos et al., Nature 515, 92 (2014)
Blumenfeld, I. et al. Nature
445, 741 (2007).
See CERN A&T seminar
with C. Joshi, Dec 18.

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Plasma wake-field, CTF3 parameters
Even at n0 ~ 1014 /cm3 the DB and WB bunches must be shorter than
what is currently available in CTF3.
On the next slides I will show a few PIC simulations where I use
parameters based on the new DB injector as plasma DB, and CALIFES as
plasma WB. Bunches is shortened as much as needed. Bunch shortening
in CTF3 can be performed by new bunch compressors.

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sz = {150, 150} um
n0 = 3.1 x 1014/cm3
ezN,DB = 10 um
s = 0.5 m
DB optimized parameters
In this scenario, the blow-out is clean until the full drive beam
depletion. Excellent emittance preservation of the WB is
predicted by the simulations.
• DB and WB must be shortened to about 150 um
• DB emittance must be reduced to about 10 um

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Summary of requirements for PWFA@CTF3
• Two independent co-linear electron beams: ~adjustable
relative timing with accuracy of ~10 fs
• Required upgrades to CALIFES :
• <~ 150 um bunch length
• as large single bunch charge as possible (ideal is >~ 1 nC, but this
is not a hard requirement)
• Required upgrades to the DB
• <~ 150 um bunch length
• >~ 100 MeV beam energy
• <~ 10 um normalized emittances (linked to other parameters, like
peak current; to be further studied)
• possibility to extract single shot (to be studied further)
• Required upgrades to CTF3 complex
• Installation of plasma cell and diagnostics
• Co-linear injection/extraction (energy based)

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PWFA - Conclusions
• In order to demonstrate the feasibility of plasma for accelerator
applications, there is need for additional test facilities.
• CTF3 has potential to perform plasma experiments; relevant to a
PWFA-LC. Complementary to AWAKE. Some overlap with FACET-II, FF.
The more precise we can control and diagnose bunches, the more
attractive CTF3 is.
• Unique possibility to do multi-bunch plasma heating experiments
possible (up to 1 GHz)
• Bunches would need to be compressed by a significant factor
• Single bunch capabilities for the DB strongly desired
• We are interested in further developing this proposal with CLIC/CTF3

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X-band technology for FELs
4/3/2015
ST Elettra - Sincrotrone Trieste, Italy.
CERN CERN Geneva, Switzerland.
JU Jagiellonian University, Krakow, Poland.
STFC Daresbury Laboratory Cockcroft Institute, Daresbury, UK
SINAP Shangai Institute of Applied Physics, Shanghai, China.
VDL VDL ETG T&D B.V., Eindhoven, Netherlands.
OSLO University of Oslo, Norway.
IASA National Technical University of Athens, Greece.
UU Uppsala University, Uppsala, Sweden.
ASLS Australian Synchrotron, Clayton, Australia.
UA-IAT Institute of Accelerator Technologies, Ankara, Turkey.
ULANC Lancaster University, Lancaster, UK.
XbFEL is a collaboration among several laboratories
aimed at promoting the development of X-band technology for FEL
based photon sources.
G. D’Auria – Elettra Trieste

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Potential tests for an X-band FEL using the CALIFES beam
4/3/2015
New hardware required Hardware already available
A. Latina (CERN) with relevant inputs from
G. D’Auria, S. Di Mitri (ELETTRA), M. Pedrozzi (PSI),
A. Dexter and G. Burt (Cockcroft, Lancaster)

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Extension of CALIFES for XFEL oriented developments.
Problematic:
• Accessibility to the accelerator facility for beam dynamics and hardware
developments is extremely limited on FEL user facilities, running 24/7 for production
Ideal requirements for CALIFES:
• S-Band RF-Photoinjector system: high brightness beam could require some optimization of the lattice and the
laser system (SITF experience is a good guideline)
• S-Band injector linac (~200-250 MeV)
• X-band longitudinal Phase space linearization (one cavity is sufficient)
• Magnetic chicane for compression: PSI could lend the mechanics, the connecting long vacuum chambers and
eventually the magnets of the SITF compressor (12m long, angle adjustable between 0° and 5°)
• S-Band deflector system for slice measurements
• Optics + high resolution COTR insensitive transverse monitor for emittance measurements: SITF design (R.
Ischebeck) and experience could be used
Study ideas:
1. Study of short pulse regime: CSR effects and development of instrumentation (in particular longitudinal)
2. Test of new generation RF photo injectors: for example S-band coaxial or C-Band (advanced design available
at PSI)
3. Development and test with beam of X-band deflector systems (post undulator instrumentation)
4. Test of X-Band acceleration modules with beam: RF aspects, alignment issues, short and long range wake.
5. Study of HOM coupler for alignment purposes (cavity + electronics): one CLIAPSI cavity available at CERN,
electronic development ongoing at PSI (M. Dehler)
If enough space available
• Demonstration of non-linear magnetic compression with negative R56 and adjustable T566. Preliminary
design study available at PSI (A. Streun). Required ~30 m and multipole magnets. Complex but:
X-band linearization not required, one important source of jitter removed  increases of compression stability.
Courtesy of M. Pedrozzi, M. Dehler, M. Leich
M. Dehler, M. Pedrozzi,
M. Leich – PSI

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Advanced Beam Physics
• Compare the performances of a purely-magnetic compression scheme,
w.r.t. one including velocity bunching, both in terms of macroscopic
properties of the beam as well as in terms of micro-bunching
• Micro-bunching gain measurements and comparison with analytical
models
• Electron beam shot-noise bunching suppression + lasing (some undulators
would be needed)
• Tests of Double-Bend Achromat (DBA) with CSR suppression
• Electron comb generation using masks in a dispersive region, and
transport control
• Tests of bunch compression with sextupoles in the dispersive region (verify
the impact on the longitudinal phase space)
• Measurement of emittance scaling with the photo-injector charge
(models predict a shift from power of ½ to 1/3 but needs more accurate
studies)
S. Di Mitri – Elettra Trieste

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Shaping ability of Masks
Multiple masks used to
study bunch shaping
PARMELA Simulation results
x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
-8
-4
0
4
8
12
x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
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0
4
8
12
x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
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0
4
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x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
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0
4
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x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
-8
-4
0
4
8
12
Normalized longitudinal position
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
Arb.
Longitudinal position [mm]
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5
Arb.
Longitudinal position [mm]
-3 -2 -1 0 1 2 3
Arb.
Horizontal profile after the mask
Final current profile
x [mm]
-12 -8 -4 0 4 8 12
y[mm]
-12
-8
-4
0
4
8
12
Before Mask
Apply
Mask
W. Gai – Argonne

42
Bunch length flexibility
4/3/2015
• In many cases a (very) short bunch length is required
• May be accessible using a magnetic chicane or dogleg (need some
compression studies, implications on off-crest phase, short range wake-
fields)
• Other possibility, RF deflector + collimator (crabbing). May also
implement a two-deflector solution (RF bump) to remove crabbing
• Should continue bunch compression studies in CALIFES 2015-2016 with
streak camera, EOS and possibly RF deflector

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4/3/2015
Other flexibility requirements
• Flexibility for single bunch / multibunch operation
• Flexibility in bunch charge – if high charge is needed, a switch between
CALIFES gun and PHIN is still possible?
• Need of double pulse (drive + probe) for impedance/wake-fields
measurements (and possibly plasma applications?). Flexibility in
drive/probe bunch distance and independent control of transverse
position/bunch charge may be critical aspects.

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Conclusions
• CTF3 in its present configuration will complete its program by end
2016 and stop operation
• There is a strong interest by the CLIC collaboration in keep using
some of its hardware and infrastructure beyond 2016
• Drive beam front-end
• Dogleg beam loading experiment
• RF testing (Xbox1, S band)
• CALIFES for equipment testing
• In particular CALIFES may be a reasonably cheap multi-purpose test
facility
• Useful within the CLIC study – potentially much wider interest
• Clear synergies with other projects/labs may help in gathering resources
and support
• CALIFES will be extremely useful already in its present form, but staged
upgrades will enhance flexibility/usefulness
• Will develop an integrated proposal including cost/resource
assessment and evaluation of scientific case of the different options
4/3/2015

45
THANKS
for your attention
4/3/2015

46
Summary of (some) possible upgrades
• Keep CALIFES for beam instrumentation test
• Add an available S-band klystron, modify waveguides
• Add a chicane, another dedicated klystron for deflector
• Change the deflector to a CR one
• Closed RF bump + collimator for bunch length control
• (Switch for the PHIN gun for higher charge)
• (Push the beam line toward the X-Box1 in CTF2)
• Or transport the 12 GHz power to CLEX
• Add a 12 GHz crab cavity for bunch length diagnostic
• (Add an undulator, a Compton scattering experiment…)
• Produce special beams for Impedance/Wakefield studies
• 2 bunches of different energies with adjustable delay
• Single bunch, short range wakes
4/3/2015

47
Previous studies – the Instrumentation Beam Line
4/3/2015
• A preliminary study has been done: “Short Pulse Capabilities of the
Instrumentation Beam Line – V. Ziemann – 6 May 2010”
- Short pulses (200 fs – 35 mm) 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
• Other option  four-bend chicane
• All equipment will be available from the DB lines (magnets, powers, chambers…)

48
Some consideration on resources
4/3/2015
• Given the present CTF3 material budget/manpower, one may
roughly evaluate the resources needed to keep CALIFES
running after 2016 to about:
• 200-300 kCHF/year (including M to P – students and PJAS)
• About 5 FTEs (staff and fellows)
• The above would include a minimum upgrade (1 ½ additional
klystron, rearrangement of test area)
• Must do a more precise evaluation for the more ambitious
upgrade options

49
Beam parameters
4/3/2015
• CTF3 Drive beam (present)
• 4 A, 1 us pulses (trains of 1-3 nC bunches, 1.5/3 GHz spacing)
• rep rate 1-50 Hz
• 50 – 125 MeV
• May provide lower energy (>10 MeV), need to study transport
• Typical beam sizes 1 × 1 mm, may easily fill round chamber, 4 cm
diameter.
• CTF3 Drive beam (new Front-End)
• 4 A, up to 140 us pulses (trains of 1-6 nC bunches, 0.5/1 GHz spacing)
• rep rate 1-50 Hz
• 10 – 100 MeV
• Typical beam sizes 1 × 1 mm, may easily fill round chamber, 4 cm
diameter.

50
CALIFES hall & infrastructure
4/3/2015
Convenient hall (42 x 8 x 2.6 m3) with proper concrete
shielding (2.8 m) and large access.
Instrumentation & klystron gallery just above
An up-to-date Laser lab, (80 m laser beam line, partly
under vacuum)
Fully equipped (conditioned air, water, access control. No
crane.
CLEX

51
4/3/2015
• JUICE (JUpiter ICy moons Explorer) Mission
• http://sci.esa.int/juice/55055-juice-mission-gets-green-light-for-next-stage-of-development/
• Launch a mission in 2022 to explore Jupiter and its potentially habitable icy moons
• Strong electron cloud environment around Jupiter
• Need to test components to electron irradiation
• ESA-CERN Collaboration Agreement
• Involvement and support of CERN KT group
• Turning CALIFES in an Electron Irradiation facility
• Both for Total Integrated Dose and Single Event Effect
• Beam energy ranging from 10-200MeV
• Large irradiation area (5x5cm minimum)
• Required fluence of 107/108 electron/cm2
• 1st test in 2015
Challenges for CALIFES
• Run at (much) lower beam energy (down to 10MeV)
• New RF acceleration scenario (to be tested)
• New test Area in CALIFES after the Gun or after 1st Acc. Structure
• Need very low flux and large and homogeneous irradiation area
• Need to qualify the beam quality (possibly cutting tails with collimators ultimately)
• Characterization and 1st testing possible on CALIFES Dump line
JUICE - CALIFES
Perspectives for e- beam irradiation tests in
CTF3/CALIFES – R. Corsini, ESA visit @CERN
https://indico.cern.ch/event/357271/
T. Lefevre – M. Brugger

52
Open issues/questions
• Verify needed fluxes (test pieces, needed area…)
• Energy range – how critical? Verify low energy capabilities in CALIFES.
• How uniform should be the beam?
• What about the time structure (average vs. peak flux)?
• Total dose needed, testing time, running scenario…
• Layout of irradiation region – activation of collimator, air activation,
dump…
• Timescale (before and/or after 2016)
• …
4/3/2015

53
Uniform beam - Filling the aperture
4/3/2015
Collimator
Test area
Beam Pipe

54
Fluxes
• 1 nC pulses @ 1 Hz (CALIFES, few bunches)
 6.25 109 e- s-1
• Assume round beam, 40 mm x 40 mm, 90% cut
 5 107 e- cm-2 s-1
4/3/2015

55
Longitudinal wake-fields
Longitudinal wakes cause energy loss and correlated energy spread (chirp)
Idea:
1. Compensate the correlated energy spread with small off-crest acceleration, and
measure the energy spread using a
spectrometer
2. Perform a phase / voltage scan
to locate the minimum
(i.e. compensation)
3. Infer wake-field characteristics from
- energy spread vs phase scan,
- energy spread vs voltage scan
A. Latina - Measurement of
Short-Range Longitudinal
Wakefields at CALIFES

56
Setup, parameters, and simulation of phase scan
CALIFES-like parameters:
• Two CLIC AS with a/λ = 0.11
• Bunch charge = 1 nC
• Average energy = 200 MeV
Two bunch configurations considered:
• Bunch uncorrelated espread = 0.25 %
• Bunch length = 1200 um
and:
• Bunch uncorrelated espread = 0.5 %
• Bunch length = 600 um
Four different longitudinal distributions
• Gaussian
• Uniform
• Forward
• Backward
The plots show the result energy spread:
400
405
410
415
420
425
0 10 20 30 40 50 60 70 80 90 100
sE[keV]
RFphase [deg]
a/l=0.11; q=1 nC, sz=1.2 mm, dE/E=0.2%
G=2.2 MV/m, Gaussian
G=20 MV/m, Uniform
G=20 MV/m, Forward
G=7.5 MV/m, Backward
998
999
1000
1001
1002
1003
1004
1005
0 10 20 30 40 50 60 70 80 90 100
sE[keV]
RFphase [deg]
a/l=0.11; q=1 nC, sz=0.6 mm, dE/E=0.5%
G=9.1 MV/m, Gaussian
G=20 MV/m, Uniform
G=20 MV/m, Forward
G=19.8 MV/m, Backward

57
Dependence on voltage is much weaker
Example: 1.2 mm bunch length, 0.2% energy spread, two distributions
Gaussian:
- Resolution required ~ 1 keV
Uniform
Resolution required ~5 keV

58
4/3/2015

59
Additional considerations II
• Decommissioning ≠ zero resources !
• It may be wise to “mothball” CTF3, also to keep open the
possibility to re-start CTF3 after 2016 if needed (new module
generation?) and according to CERN priorities
• Hovever, this clashes with requests to re-use CTF3 buildings and
equipment…
• The shut-down paradox:
“Given an accelerator facility, the cost of running it is in
general lower or equal than the cost of a shut-down”.
4/3/2015
G. McMonagle

60
CALIFES
4/3/2015
Parameters Specified Verified Comment
Energy 200 MeV 205 MeV Without bunch compression
Norm. emittance < 20 p mm.mrad 4 p mm.mrad With reduced bunch charge
Energy spread < ± 2 % ± 0.5 %
Bunch charge 0.6 nC 0.65 nC With new photocathode
Bunch spacing 0.667 ns 0.667 ns Laser driven
Nb of bunches 1-32-226 from 1 to 300 Limited by RF pulse length
rms. bunch length
< 0.75 ps
1-2 ps and
above
Repetition rate 0.8 – 5 Hz 0.8 – 5 Hz Upgrade possibility to 10 Hz
• Up to now used on TBTS,
from November:
 Two-Beam module
• Growing activities over
the last years on beam
diagnostic/components
testing
CALIFES
Swiss FEL
injector (courtesy
Simona Bettoni)

61
Beam Diagnostic Tests in CLEX
4/3/2015
Stripline Drive
Beam BPM in TBL
(CERN-LAPP)
Electro-optic bunch
profile monitor
in CALIFES
(CERN-Dundee University)
Cavity Main Beam BPM
in CALIFES/TBTS
(CERN-JAI at Royal Holloway)

62
X-band
4/3/2015
• CALIFES may provide an unique opportunity to test X-band
structures/modules with beam
• XBOX1 located very close (distance comparable to present low-loss
line for dog-leg beam loading experiment)
• Straight-forward solution: connect to XBOX1 for beam testing in CLEX
• An upgraded CALIFES beam may be not too far from what is needed
for FELs: “Playing ground” for X-band FEL beam studies and
developments
• Future possibility: test a full X-band module (for X-band FEL or klystron-
based CLIC) – may need an additional modulator/klystron
• Add more? …

63
Layouts?
4/3/2015
4.7m
26.5 m 42 m
8m
Stand
Alone Test
Stand
4.7m
26.5 m 42 m
8m
Stand
Alone Test
Stand
Low loss circular waveguide

64
Options
4/3/2015
Lepton Injector
Chain
CALIFES
facility
DB Front End
Dog-leg

65
CTF3 Decommissioning issues
4/3/2015
G. McMonagle

66
CTF3 Decommissioning & re-use issues
• Simplest solution close the complex and lock the doors
• Continue running CTF3
• Costs
• New access control system needed
• Upgrade of modulator controls (get rid of non supported CAMAC)
• manpower
• Reuse the Linac and rings for electron injector to PS
• Costs
• New access control system needed
• Upgrade of modulator controls (get rid of non supported CAMAC)
• manpower
• CLEX
• Keep CALIFES operational
• New access control system needed SOLVED
• New DB injector test area
• Use LINAC area but probably need civil engineering work in CTF2 area to allow
modulators and klystrons to be installed (too large for gallery)
• CTF2
• Continued PHIN tests, X band test area
• New access system needed SOLVED
4/3/2015
G. McMonagle

67
Yearly cost of CTF3 running
2012 running, relevant budget codes in blue
Include some consolidation and upgrade

68
Yearly cost of CTF3 running
Taking out upgrades, divided by sub-systems
340
13
170
26
890 (1200)
58
50
+ Manpower: about 15 FTE, including M to P
1550 (1860)
Spent 2013
(kCHF)

69
Contribution to AWAKE
• Awake needs 20 MeV electron source
with low charge, small emittance and
possibly short bunches
• One CTF3-type Klystron-Modulator
would be needed to power the
injector
• PHIN (Califes) type gun could be used
• Some diagnostics, vacuum equipment
and magnets might be useful
• CTF-team experience would be likely
helpful as well
• Test facility and pre-commissioning in
CTF2 area?
4/3/2015
Proton beam line
2m
2m
10m
Lasers
Plasma cell
(10m long)
Electron spectrometer
Electron gun
Klystron system
CNGS target area
Access gallery
Experimental
Diagnostics
Laser & proton beam
junction
Items in dark blue: ventilation ducts
Items in light blue: AWAKE electronic racks
Items in cyan: existing CNGS equipment (cable trays, pipes,…)
Laser power
supplies
Electron beam line

The future of CTF3

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