ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

DIELECTRIC BASED HG STRUCTURES: POWER EXTRACTION, TUNABILITY AND

ENERGY TRANSFER EFFICIENCY

A. KanareykinEuclid Techlabs LLC in collaboration with AWA,ANL

ICFA Workshop on Novel Concepts for Linear Accelerators and

Colliders. SLAC, July 7-10 2009

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

ANL/Euclid Techlabs Collaboration on Dielectric Wakefield Acceleration

Euclid Techlabs: C.Jing, P.Schoessow, S.Antipov, F.Gao and A.Kanareykin

Argonne National Lab: M.Conde, J.G.Power, R.Conecny, Z.Yusof and W.Gai.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Motivation/Outline

High Gradient DLA

26 GHz Wakefield Power Extractor

Tunable Dielectric Based Accelerator : Idea and Experiment

Ferroelectric Based Fast High Power Switching

Transformer Ratio X-Band Experiment, R>2 Demonstration

Energy Modulation

MW DLA issues: high gradient – drive beam, power extraction, tuning, efficiency, BBU, multipacting, …

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Drive Gun

Linac & Steering Coils Quads

Wakefield Structure

ExperimentalChambers 4.5 m

GVGV

YAG1 YAG2

Spectrometer

YAG5Dump/Faraday Cup

Slits

YAG4YAG3ICT1

ICT2 BPM

Single bunch operation– Q=1-150 nC– Energy=15 MeV– High Current = 10 kAmp

Bunch train operation64 bunches x 50 nC 50 ns long

Dielectric Based Accelerator

b a

Q

Cu

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Ne

~ 100 GeV Module

Ne

~ 1 GeV drive beam

~ 100 GeV Module

Major features: Short pulses (<20 ns), high gradient (200 ~ 300 MV/m)Drive beam structure directly

Many of the ~ 100 GeV Modules

~ 1 GeV drive beamPhotonsPhotons

Dielectric Based Linear Collider

Concepts

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

26GHz Dielectric-Based Power Extractor*

• A 26GHz power detector has been built and bench tested.

• A load has been built and bench tested.

• Beam test has been performed at AWA facility.

Parameters of 26GHz Dielectric Based RF Power Extractor

Geometric and accelerating parameters value

ID / OD of dielectric tube 7 mm /9.068 mm

Dielectric constant 6.64

Length of dielectric tubes 300 mm

R/Q 9788 /m

Drain time Td 3 ns

Steady power from AWA bunch train (20nC/bunch)

148 MW

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Beam Test of the 26GHz Power Extractor @ AWA Facility (May~June, 2009)

Load

Rf probe

LO=14.576GHz

11.424GHz BPF (228MHz

BW)

16GHz scope

Performed 3 experiments to date:

• Single beam--- to check the frequency

• 16-Bunch train--- to check the rf pulse formation

• 4-bunch train--- to achieve the high rf power

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Down-converted rf Trace of the 26GHz Power Extractor (4bunches)

11.44+14.576=26.016 GHz

Background noise direct to the scope

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Down-converted rf Trace of the 26GHz Power Extractor (16 bunches with 769ps separation)

11.44+14.576=26.016 GHz

4 bunches to reach the steady state

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Number is the percentage of charge transmission out of the structure.

Charge Sweeping

•Theoretically, 9nC29.6MW, 24.8MV/m if σz=1.5mm.

•Calibration will be taken after the experiment.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Summary for 26GHz Dielectric Based Power Extractor

Successfully demonstrated the high frequency, high power rf source using dielectric-based scheme.

Experiment will be continued in the upgraded AWA facility next year.

Design of a fully featured power extractor( with transverse modes damping) is needed to prevent BBU in the high charge transportation.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Tuning/Nonlinear Effects in Dielectric-Based

Accelerator

forsterite BST(M)

ε(E) for ferroelectric dielectric composite

Pulse steepening

high intensity wakefields in nonlinear structure

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Temperature tuning of 14 MHz/0K

Tunable DLATemperature Tuning*

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Tunable DLAFast DC Voltage Tuning

6 MHz at 20 kV/cm

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

0 1 2 3 4 5 6 7 8

E, V/um

K

95_1_1

95_1_2

95_3_1

95_3_2

95_5_1

95_5_2

95_8_1

95_8_2

95_2_1

95_2_2

95_4_1

95_4_2

95_6_1

95_6_2

95_7_1

95_7_2

epsilon(0)

0

50

100

150

200

250

300

1_1 1_2 3_1 3_2 5_1 5_2 8_1 8_2 2_1 2_2 4_1 4_2 6_1 6_2 7_1 7_2

серия 95

Е=5В/мкм

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1 3 5 8 2 4 6 7

серия 95

K

KdcKpulse

New Ferroelectric

Lower dielectric constant, higher tuning range

ε< 300, k> 10% in air

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

BST(M) Ferroelectric Based L-band High Power Tuner

30 ns switching speed

Collaboration with Omega-P and FNAL

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Transformer Ratio

R < 2 under very general conditions: linear media; a relativistic, longitudinally symmetric drive bunch; and identical paths through the system of both drive and witness beams.

Transformer Ratio R = (Max. energy gain behind the bunch) / (Max. energy loss inside the bunch).

Distance behind the bunch, cm2520151050

Wakefield

, M

V/m 30

20

10

0

-10

-20

-30

W+

W- R= W+ /W-

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

(z)

z W -

W+

zd d

W -

W+

d

(z)

Reference: Bane et. al., IEEE Trans. Nucl. Sci. NS-32, 3524 (1985)

Reference: Schutt et. al., Nor Ambred, Armenia, (1989)

Some of the methods that can be employed to obtain R>2 include: a triangular drive bunch longitudinal profile; a train of Gaussian drive bunches of progressively increasing charge (ramped bunch train, RBT); the ring type driver, use of a proton drive beam so that the particles within the bunch can change positions during deceleration; and nonlinear plasma dynamics.

A single drive bunch was replaced by two bunches with charge ratio of 1:2:5 and a separation of 10.5 wavelengths of the fundamental mode

Ramped Bunch Train

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

LO (8.3GHz)

Signal from the field probe (13.6GHz) Signal to

the digital scope (5.3GHz)

LO (8.3GHz)

data (13.6GHz)

softwareDLA

6GHz digital scope

two-bunch wakefield experiment setup

Wakefields measurements

The field probe signal from the RBT in the 13.625 GHz DLA

Transformer Ratio Experiment

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Leading and Tailing 8 nC and 20 nC

bunches

satisfying the requirement of an equal decelerating field inside each bunch

the transformer ratio increases correspondingly, from R~ 1.8 to

R~ 3.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Enhancement Factor of 1.31

Transformer Ratio R~2.3

An average measured transformer ratio enhancement by a factor of 1.31 over the single drive bunch case was obtained, R>2 has been demonstrated.

C.Jing, A.Kanareykin, J.G.Power et al. PRL 98, 144801, 2007

R>2 Experimentally Demonstrated.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

4 bunch Transformer Ratio Experiments

time (ps)

Inte

nsi

ty (

arb

. uni

t.)

40 30 20 10 0 10 20 30 40

time (ps)

Inte

nsi

ty (

arb

. uni

t.)

40 30 20 10 0 10 20 30 40

time (ps)

Inte

nsi

ty (

arb

. uni

t.)

40 30 20 10 0 10 20 30 40

time (ps)

Inte

nsi

ty (

arb

. uni

t.)

40 30 20 10 0 10 20 30 40

zd d

W -

W+

d

(z)

laser pulse stacking method to stretch the AWA laser pulse from FWHM = 8 ps to 26.5 ps.

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Energy Modulated Bunch Train

Sequence of four bunches

z, cm1101009080706050403020100

Wak

efie

ld, M

V/m

550

500

450

400

350

300

250

200

150

100

50

0

-50

-100

-150

Sequence of four bunches

z, cm1101009080706050403020100

Wakefie

ld, M

V/m

140

120

100

80

60

40

20

0

-20

-40

-60

-80

-100

-120

-140

Ramped – 220 nC;Flat – 80 nCFor the same gradient:

A.Kanareykin et al, in preparation

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Sequence of four bunches

z, cm1101009080706050403020100

Wak

efie

ld, M

V/m

140

120

100

80

60

40

20

0

-20

-40

-60

-80

-100

-120

-140

Energy

Charge distribution is 20-20-20-20 nC, 1.5 mm length AWA bunch generated at the diamond based DLA structure with the inner radios of 1.5 mm, outer radius of 2.62 mm, ID=3 mm, OD= 5.24. Spacing between the bunches corresponds to 1.3 GHz or ~ 23 cm. Maximal accelerating gradient behind the train is 150 MV/m.

Energy Modulated Bunch Train.Energy Distribution

(10-30-50-70) MeV Train

A.Kanareykin et al, in preparation

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

Cons:- lower accelerating gradient- high charge for the last bunches- transverse fields increase- focusing for ramped bunch charges

Ramped Bunch Train

Pros:- laser beam manipulation for the train profile generation

Energy Modulated Bunch Train

Pros:- higher accelerating gradient- flat and low charge bunch train- last bunches have higher energy - transverse stability

Cons: - energy modulated driver bunch train generation - focusing of the energy profiled bunch train

Energy Modulation: pros and cons

A.Kanareykin et al, in preparation

ICFA Workshop on Novel

Concepts for Linear Accelerators and Colliders.

SLAC, July 7-10 2009

Euclid Techlabs LLC

SUMMARY

1. Successfully demonstrated the 26GHz, high power rf source using dielectric-based scheme.

2. Design of a fully featured power extractor ( with transverse modes damping) is needed to prevent BBU in the high charge transportation.

3. Tunable dielectric based accelerator concepts is presented

4. Transformer ratio experiment demonstrated R>2 for DWA

5. Energy modulated beam is considered, pros and cons are discussed.