ADVANCED ACCELERATOR TEST FACILITIES AT DARESBURY

LABORATORY

Peter McIntosh (STFC Daresbury Laboratory)2nd PASI Workshop, RAL April 3 - 5, 2013

• Daresbury Test Facilities:– ALICE:

• SRF Cryomodule R&D• RF Control – Microphonics and Lorenz Detuning

– EMMA NS-FFAG:• Beam Dynamics Studies• RF Control – Vector Sum Architecture

– VELA:• Deflecting Cavity Diagnostics

• Collaborative Opportunities• Conclusions

Overview

• ALICE at Daresbury Laboratory operates using Energy Recovery principle.

• Only accelerator of its type in Europe.• Used as an R&D test facility for next

generation electron beam technology development.

Booster

Compressor

IR-FEL

Photoinjector Laser

Linac

Acceleration

Deceleration

8 MeV

35 MeV

8 MeV

http://www.stfc.ac.uk/ASTeC/Programmes/Alice/35997.aspx

ALICE ERL Facility

ALICE Operating ParametersParameter Design Value Operating Value

Gun Energy (keV) 350 320

Injector Energy (MeV) 8.35 7

ERL Energy (MeV) 27 23

Total Beam Energy (MeV) 35 30

RF Frequency (GHz) 1.3 1.3

Bunch Repetition Frequency (MHz)

81.25 81.25/16

Train Length (µs) 0 - 100 0 - 100

Train Repetition Frequency (Hz) 0 - 20 0 - 20

Compressed Bunch Length (ps) <1 rms <1 rms (measured)

Bunch Charge (pC) 80 40/80

Energy Recovery Rate (%) >99 >99 (measured)

New SRF Cryomodule

• Collaboration formulated in early 2006 to design and fabricate new CW cryomodule and validate with beam.

• Dimensioned to fit on the ALICE ERL facility at Daresbury:– Same cryomodule footprint.– Same cryo/RF interconnects.– ‘Plug Compatible’ with existing

cryomodule.

Parameter Target

Frequency (GHz) 1.3

Cryomodule Length (m)

3.6

R/Q () 762

Eacc (MV/m) >20

Epk/Eacc 2.23

Hpk/Eacc 46.9

CM Energy Gain (MeV) >32

Qo >1010

Qext 4 x 106 - 108

CM Component Testing

DESY superstructures (7Z2 & 7Z4) modified to incorporate optimised end groups.

Saclay-II tuner with wider aperture and low voltage piezo cartridges, pinned and stress tested.

Modified Cornell ERL injector coupler with a shortened cold section, high

power conditioned.

Cavities, cold couplers and central HOM absorbers installed. Cryomodule assembled & undergoing final cold testing.

Assembly and Integration

DLLRF Implementation• LLRF4

– Designed at LBNL by L.Doolittle– Open source– Xilinx spartan 3 FPGA– 4 -14 bit ADC Channels– 2 -14 bit DAC's– USB comms– Clock management chip

• Cost ~$3k, built and tested• System installed in 2011 on NC

buncher cavity.• To also install on SRF cavities:

– 1.3 GHz.– High Q Superconducting Cavities.– 4ms pulse & CW– Fast feedback– Feed Forward for beam loading

compensation.

Parameter ValueEnergy range 10 – 20 MeV

Lattice F/D Doublet

Circumference 16.57 m

No of cells 42

Normalised transverse acceptance

3 mm

Frequency (nominal) 1.3 GHz

No of RF cavities 19

Average beam current 13 μA

Repetition rate 1, 5, 20 Hz

Bunch charge 16-32 pC single bunch

EMMA NS-FFAG

EMMA is the only accelerator of its type in

the world!

http://www.stfc.ac.uk/ASTeC/Programmes/17426.aspx

Applications of NS-FFAGs

High power proton driver

Neutrino Factory Proton & Carbon Therapy

Dedicated Muon Source Accelerator driven reactor

• Fixed energy operation to map closed orbits and tunes vs momentum

• Many lattice configurations

– Vary ratio of dipole to quadrupole fields

– Vary frequency, amplitude and phase of RF cavities

• Map longitudinal and transverse acceptances with probe beam from ALICE

• EMMA is heavily instrumented with beam diagnostics

EMMA Objectives

IonPump

CavityD Magnet

F Magnet Location for diagnostics

Beam direction

Girder

EMMA 6-Cell Girder Assembly

YAG Screen YAG

Screen

eBPM x 81

SeptumPowerSupply

KickerPowerSupplies

SeptumPowerSupply

KickerPowerSupplies

EMMA Ring ConfigurationWall Current

Monitor

LLRF

First user of Libera LLRFLocated ~ 30 m from machine

Realisation of EMMA August 2010

First Turn Second Turn

16th Aug 2010

Optimising RF for Acceleration• ToF zero crossing of each

cavity to find optimum phase angle.

• Beam loading effects could be seen on Libera system during phase optimisation.

• Possibility to zero cross each cavity, tune for maximum acceleration.

• Close Libera RF control loop to keep track of the correct phase of the system:– phase accumulator is reset

during sweep.

• LLRF control essential in order to achieve successful beam acceleration.

EMMA Acceleration Achievement

• Successful acceleration in serpentine channel demonstrated.

• Published in Nature Physics (01/03/12)

MeasuredMarch 2011

VELA – Versatile Electron Linear Accelerator (ex EBTF)

• For the development and testing of novel and compact accelerator technologies.

• Through partnership with industry and the scientific community.

• Aimed at addressing applications in medicine, health, security, energy, industrial processing and science.

• Will enable research into areas of accelerator technologies which have the potential to revolutionise the cost, compactness and efficiency of such systems.

• The main element of the infrastructure:- high performance and flexible electron beam injector facility feeding customised state-of-the-art testing enclosures and associated support infrastructure.

• Critical for development of underpinning technologies; – Advanced Beam Diagnostics, – Accelerating and Dipole Mode RF Structures, – RF Sources and Distribution Systems,– Vacuum Systems, – Magnet Systems,– Beam-based Feedback and Control Systems,– Beam Synchronisation Systems.

VELA Pulsar

Module 1

Module 2

Module 3

Module 4

Module 5

Module 6

Module 1

Accelerator Modules

http://www.stfc.ac.uk/ASTeC/Programmes/EBTF/38426.aspx

VELA/CLARA Beam Parameters

VELA (Min) VELA (Max)CLARA

(single spike)Min/Max

CLARA (seeding)Min/Max

Comments

Beam Energy 4 MeV 6 MeV 6 /25 MeV 6 /25 MeV

Magnets in VELA can go up to 25 MeV later for CLARA and some diag devices will be used at this higher energy.

Bunch Charge 10 pC 250 pC 10 pC 250 pC Experimental modes

Bunch length (σt,rms) 80 fs 3 ps35 fs /3ps(@25 MeV)

50 fs /3ps (@25 MeV)

Bunch length changes along the line. CLARA in bunch compression mode. Experimental modes.

Normalised emittance

0.1 m 2.0 m 0.1/1 µm 0.6/3.0 µm CLARA in bunch compression mode. Experimental modes

Beam size (σx,y,rms) 0.1 mm 3.5 mm 0.1/2.0 mm 0.1/4 mm Varies along the beam line

Energy spread (σe,rms) 0.1% 5% ~ 0.1/1 % ~ 0.1/5% Varies along the beam line

Bunch repetition rate 1 Hz 400 Hz TBD TBDKlystron Modulator & Laser 400 Hz

Transverse Deflecting Cavity Beam Diagnostic

Parameter ValueNumber of cells 9Frequency (MHz) 2998.5Nominal/Maximum RF voltage (MV) 5Nominal/Maximum RF power (MW) 5/6Operating Mode πRepetition rate (Hz) 10Active length (m) 0.5Quality factor (Qo) ~18000Shunt Impedance deflecting mode R (MΩ) 5.0Aperture beam pipe diameter (mm) 35 (Iris 32)

H-field

E-field

TDC CharacterisationEstimated peak transverse voltage 5 MV (limited by available RF power)

3-cell TDC prototype (RI GmbH)

VELA Status and Layout

Injector Room Enclosure 2

Rack Room

Synchronisation Room Laser Room

Control Room

First electrons by end April 2013First beams for exploitation July 2013.

• SRF Cryomodule Operation (ALICE):– CW SRF Cavity Operation:

• Thermal Characterisation– Microphonics Assessment & feedback/forward Control

• NS-FFAG Beam Dynamics (EMMA):– Serpentine Acceleration– RF Control Processes– Slow RF acceleration – Induction techniques?– Magnet Systems (Conventional & SC)

• Deflecting/Crab Cavities (VELA/ALICE/EMMA):– Structure Designs– RF Control Developments

• Vacuum Systems (VELA/ALICE/EMMA)

Collaborative Opportunities

• Innovative and unique accelerator test facilities available at Daresbury:• ALICE – Europe’s only ERL Facility• EMMA – World’s only NS-FFAG• VELA – High performance beam injector

• Each allow for technology development and/or demonstration.

• Although machines use electrons, compliance exists for proton technologies:• Accelerator Systems• RF Control/feedback/feed-forward/synchronisation• Deflecting/Crab Cavity Systems (Diagnostics/Beam

Manipulation)• Magnets• Vacuum Systems

• Opportunity to explore UK-FNAL collaboration in these (or other) areas.

Conclusions

THANK YOU!