The Upgraded Argonne Wakefield Accelerator Facility

(AWA)

A testbed for the development of high-gradient accelerating structures and wakefield

measurements.HG2013, Trieste, Italy, June 4th, 2013

Argonne National Laboratory:

Euclid Techlabs LLC:

Students:

W. Gai , M. Conde, S. Doran, W. Liu, J. G. Power, C. Whiteford

S. Antipov, S. Baryshev, C. Jing, J. Qiu , R. Konecny, A.Kanareykin, P.Schoessow

E. Wiesniewski (IIT), C. Li, H. Zha (Tsinghua), G. Ha(POSTECH).

Primary mission

R&DBeam Driven Dielectric Wakefield Acceleration

Funding High Energy Physics

2b 2a

eQ

Cu

21

e N

r

)cos(2exp)(2

2 kzaQzW

n

zZ

Wakefields in Dielectric Structures

short Gaussian beam

Wakefield Amplitude Dependent on a

1

10

100

1000

10000

100000

0.01 0.1 1 10

Inner Radius a (mm)

Ez(

MV

/m/1

0nC

)

Key to the success:Drive beam, drive beam and drive beam!• Charge • r (Energy or Emittance )• Bunch length

Dielectric-Loaded Accelerator Structure

Simple geometry Inexpensive Capable of high gradients Easy to damp dipole modes Tunable

Electric Field Vectors

OUTLINE

High Gradient Concepts Collinear wakefield acceleration Two beam acceleration (a.k.a. Parallel wakefield acceleration)

Applications A high energy physics collider An x-ray free electron laser THz generation

The Argonne Wakefield Accelerator Facility Then Now

CONCEPTS

Collinear wakefield acceleration &Two-beam acceleration(Parallel wakefield acceleration)

Collinear Wakefield Acceleration

Drive Beam(EM power source)

Witness Beam(accelerated beam)

Metal

DielectricVacuum

Recent results (obtained for Linear Collider development):− 1000MV/m level in the THz domain (UCLA/SLAC group)− 100 MV/m level in the MHz domain (AWA/ANL group)

Two-beam acceleration(Parallel wakefield acceleration)

Mode LockedUV Laser

Klystron1.3G

Hz,

25MW

, 8us

Modulator250KV,

250AMPs

1. Drive beam generation

Photons2. RF power generation

3. High Gradient Acceleration

(A FEW) APPLICATIONS

1. e+ e- linear collider2. X-ray light source3. THz generation

1. e+ e- collider

25 MV/m, 0.5 TeV, 31 km

Current Approach: superconducting RF

HEP

Argonne Approach: Flexible Linear Collider*

Core of the two-beam acceleration concept:1. Short rf pulse: tens of nanosecond2. Modular TBA scheme: energy scalable easily

250 MV/m, 3 TeV, 18 kmtwo-beam acceleratio

n

HEP

*(See C. Jing’s talk)

2. Multiuser X-ray FEL User Facility

expe

rimen

tal e

nd s

tatio

ns

2 GeV50 MeV

~1 MHz injector

Laser-like X-raysCapable of serving

~2000 scientists/year

—Current Approach—superconducting RF

$$$

BES

Flexible x-ray beamlines (Tunable pulse length, seeded, 2 color seeded, SASE)

(like 3rd generation light sources) (like 4th generation light sources)

~100 kHz X-rays

Beam Spreader

Argonne Approach dielectric wakefield accelerating linacs

~50 m

~25 m

3. Low EnergyBeam

Spreader

Facility Footprint350m x 250m

~50 m

~50 m

350m750m

expe

rimen

tal e

nd s

tatio

ns

~30 m

1. High Gradient (100 MV/m) DWFA linac2. Room Temperature dielectric

~100 m ~50 m

2 GeV200 MeV

extremely low-cost

alternative

Collinear wakefield acceleration

BES

Ultra-flexible facility

ConfigurableFEL Array

1 keVX-rays

End S

tations

1.2 GeV100 pC

Flexible x-ray

beamlines

Flexible accelerator beamlines

……

……

ConfigurableDWFA Accelerator

0.5 keVX-rays

2.4 GeV50 pC

dielectric wakefield accelerating linacs

Collinear wakefield acceleration

3. THz generation: Capability gap BES

15

AWA ATF BNL

7.8GHz power extractor (40MW) 100MV/m gradient demonstration Enhanced Transformer Ratio: 3.4 Tunable DLA structure 26GHz power extractor Diamond breakdown experiment (300MV/m) Bunch Train generation at the AWA Wakefield Mapping diamond

THz source at AWA Chirp correction

Tunable THz GV/m

1GHz 10GHz 30GHz 100GHz 300GHz 1THz 3THz

FACET SLAC

Tunable 0.3-10 THzHigh power (155 mJ)

Narrow band (1% BW)

Argonne Approach: dielectric wakefield accelerator-based

Energy modulation via self-wakefield

Chicane energy modulation conversion to bunch train

THz radiation wakefield structure

THz

Flexible: each step has a tuning range

Measured beam spectrum

Energy chirped rectangular beam

Measured beam spectrum

Energy modulated rectangular beam

Bunch train frequency content

Tunable 100% source: Range: 0.3-1.5 THzPulse bandwidth: 1%Energy in pulse: ~ mJ

AWA (10nC / 6.3mm) 0.5 GW peak, 0.3THz, 320ps pulse, 1%BW, 155mJ pulse

Stage I Stage II Stage III

THE AWA FACILITY

Then

Highlights of the Accelerator R & D group in the past Invented the direct wakefield

measurement technique. First demonstration of collinear

Wakefield Acceleration: – Dielectric Structures, Metallic Structures, and

Plasmas First Ever plasma wakefield acceleration

in underdense regime (non-linear) (with UCLA).

First Ever 100 nC RF photocathode gun and Linac.

First Ever high power RF generation from dielectric wakefield structure accelerator.

First Ever dielectric based two beam acceleration experiment.

Discovered new multipactoring regime in dielectric structure.

Collinear wakefield

Two-beam

Drive beam generation

RF generation

The AWA facility (PAST, ca. 2008)

rf-gun

soleniodlenses

8 MeV 15 MeV

Laser In Linac

Quads SpectrometerYAG2YAG1

Direction of beam propagation

Experimental Area

Single bunch operation• Q = 1-100 nC (reached 150 nC, World record?)• 15 MeV, 2-2.5 mm bunch length (rms), • emittance < 200 mm mrad (at 100 nC)• High Current: ~10 kABunch train operation• 4 bunches x 20 nC (current) • 16 bunches x 5 nC (current)

AWA Laser System

~ 1 meter

RF power generation (PAST)Dielectric-Loaded deceleration waveguide

TM01-TE10 coupler

rf output port

11.44+14.576=26.016 GHz

Downconverted signal

7.8 GHz40 MW

26 GHz20 MW

Dielectric Power Extractors

Power limited by drive beam

High Gradient Dielectric Wakefield Test (PAST)

Wakefield Measurements:

e

Cu

Gradient limited by drive beam

Q=75 nC

8.6 GHz100 MV/m

#4 Q3.8-25.4

Quartz3.75

8.6 GHz1.9 mm

7.49 mm25.4 mm

1.33 MV/m/nC75 nC

100 MV/m

THE AWA FACILITY

Now

Key components of the AWA Upgrade

15 MeV beamMg photocathode

4. Cs2Te photocathode

3. beamline switchyard

2. 15 MeV witness beam

1. 75 MeV drive beam: RF gun &six rf cavities

…Before

After…

1.Drive beam: 15 MeV 75 MeV

2.Restore two beam accelerator capability

3.Beamline switchyard4.High quantum efficiency cathode

Higher RF power generation: 40 MW ~ GW levelHigher gradients:100MV/m 0.5 GV/m in long structuresSustained acceleration: witness DE: 1MeV ~ 100 MeVRestore two beam accelerator capability:Drive bunches to excite wakefields & acceleration of witness

bunch.Beamline switchyard two-beam-accelerationstagingcollinear wakefield accelerationphase space manipulation

Capabilities of the AWA Upgraded Facility

The AWA Upgrade drive beam

drive gun

Direction of beam propagation 75 MeV

Upgrade Goals

Upgraded Drive Beam (Targets) Single bunch operation

– 75 MeV – Q = 0.1-100 nC– @ 100 nC

• z = 2 mm• High Current: ~16 kA

– emittance < 200 um Bunch train operation

– 10 bunches x 100 nC – 32 bunches x 30 nC – Train Length = 10 - 50 ns

Original Drive Beam (Achievements) Single bunch operation

– 15 MeV – Q = 0.1-100 nC – @ 100 nC

• z = 3 mm• High Current: ~11 kA

– emittance < 200 um Bunch train operation

– 4 bunches x 20 nC – 16 bunches x 5 nC– Train Length = 10 - 25 ns

The AWA upgrade beamlines

• EEX• Bunch compression

15 MeV witness beam

• RF power generation• Collinear Wakefield• TBA• Wakefield

Measurement

75 MeV drive beam

experimental area

75 MeV drive beamline installed Feb 2013

Planned RF Power Generation

Freq. (GHz) Aperture (mm)

L (cm)

Q (nC)

z (mm)

Form factor

Grad. (MV/m)

Power (MW)

C-Band (7.8) 12 30 100 2.5 0.92 62 1107

X-Band (11.7) 10 30 80 2.5 0.83 79 1012

Ku-Band (15.6) 8 30 60 2.3 0.75 88 766

K-Band (26) 6 30 30 1.7 0.65 75 276

W-Band (91) 2 30 10 1 0.16 50 14

26GHz power extractor

X-Band (11.7) 8.7 30 60 2.3 0.85 90 441

K-Band (26) 7.5 30 40 2 0.55 100 410

Dielectric

Metallic (2pi/3 mode)

11.7GHz metallic power extractor is under development

Planned Two Beam Acceleration Experiment

drive (75MeV)16 bunches x 60nC/bunch,

z=2mm

26GHz Stage I DWPE a=3.5mm; b=4.53mm;

eps=6.64; L=30cm

26GHz Stage II DLAa=3mm; b=5.03mm;

eps=9.7; Vg=11%c; L=30cm

drive (65MeV) -10MeV (loss)

Ez = 250MV/m

RF Power Generation• 767MW x15ns• 26GHz rf

witness (10 MeV)Q=1nC, z=1mm, e=1.5 um witness (85 MeV)

+75 MeV (gain)

Development of 26GHz short pulse DLA structure

parameters valueID / OD of dielectric tube 3 mm /5.025 mm

Dielectric constant 9.7

Length of dielectric tubes 105 mm

Vg 11.13%c

R/Q 21.98 k/m

Q (loss tan=10^-4) 2295

Shunt impedance 50.44 M/m

Eacc for 316MW input 158 MV/m

Longer Term Goal: Staging for Two Beam Acceleration

Drive Beam

Witness Beam

stage I stage II

Option 1Reverse the beam

Witness Drive

2m

0.5m D=2

Witness Beam

Drive Beam

Option 2

Reverse the RF

Delay the RF

Witness Drive*Option 3: Delay the beam

Planned collinear wakefield acceleration @ AWA

75MeV beam

8 bunches

40nC/per bunch

σz=2mm

Beam Parameters

Structure Parameters

Estimated Gradient

~500MV/m on axis

• Beam hole=3mm

• Quartz tube

• Freq.=29.9GHz

drive z-directionwitness z-direction

at the AWA Facility

Planned demonstration of bunch shaping using a double-dog leg EEX beamline for high R

chirp

RF Photocathode Gun

Linac Quads

multiple masks on motorized actuator

20 deg

15 MeV

B1 B2 TDC

8 MeV

B1B2 B3 B4

Key tunable parameters

x’ slopex, y beam size

TheArgonne Wakefield Accelerator Facility

Low Energy (15 MeV) beamline

Planned demonstration of bunch shaping using a double-dog leg EEX beamline

Example: Experiment I - Shaping capability

Multiple masks will be used to study the bunch shaping capability of the double dog-leg EEX beamline

Drive Diagnostic Beamline

dumpA

A A

2m

15 deg

1m

1mdump

Def Cav

0.762m1.0 m1.0 m

DIAGX4 DIAGX1DIAGX2

1.5 m

DIAGX3DIAGX5DIAGX6

DIAGX7 0.4 mEnd of linac

Cav 6A

1mDIAGX8 0.762m

OTRYAG+mirror

Trim BPMSlit ICT Quad DIAGNOSTICCROSSA USAF

target

Transverse: ey,rms,normalized [mm]

Longitudinal: z [mm]

Transverse: x,y[mm]

Q[nC]

75 MeV

Longitudinal: Dp, p [MeV]

TESTAREA

To be installed Summer 2013

SUMMARY

Applications e+ e- collider XFEL RF-THz power generation High Transformer Ratio Two-beam acceleration Collinear wakefield

acceleration

AWA facility capabilities 75 MeV Drive

− Microbunch charge: 100 nC − Train charge: 1000 nC (10 x 100 nC, 32 x 30 nC)− Ramped trains & single bunches 15 MeV Witness (1-100 nC) Next steps

Drive and witness beamlines are installed, Awaiting final safety approval

Drive beamline commisioning – Summer-Fall 2013 Generate and characterize single bunches and

trains Condition 6 RF cavities Install diagnostic beamline Begin full beam commissioning at 75 MeV

First wakefield experiments – Fall 2013 Wakefield measurement system– 2014