ICFA Workshop on Novel Concepts for
Linear Accelerators and Colliders.
SLAC, July 7-10 2009
DIELECTRIC BASED HG STRUCTURES:
POWER EXTRACTION, TUNABILITY AND
ENERGY TRANSFER EFFICIENCY
A. Kanareykin
Euclid Techlabs LLC in collaboration with AWA,ANL
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
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.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Motivation/Outline
MW DLA issues: high gradient – drive beam, power
extraction, tuning, efficiency, BBU, multipacting, …
 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
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Dielectric Based
Accelerator
Linac &
Steering Coils
Drive
Gun
e
Wakefield
Structure
2b 2a
Spectrometer
Quads
Experimental
Chambers
4.5 m
ICT1
YAG1
GV
Q
YAG2
GV
YAG3 YAG4
ICT2
Cu
YAG5
Slits
BPM
Dump/
Faraday Cup
Single bunch operation
– Q=1-150 nC
– Energy=15 MeV
– High Current = 10 kAmp
Bunch train operation
64 bunches x 50 nC  50 ns long
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Dielectric Based Linear
Collider Concepts
~ 100 GeV Module
~ 100 GeV Module
Many of the ~ 100 GeV Modules
Ne
Photons
~ 1 GeV drive beam
Ne
Photons
~ 1 GeV drive beam
Major features: Short pulses (<20 ns), high gradient (200 ~ 300 MV/m)
Drive beam structure directly
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
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
ID / OD of dielectric tube
Dielectric constant
7 mm /9.068 mm
6.64
Length of dielectric tubes
300 mm
9788 /m
R/Q
Drain time Td
3 ns
Steady power from AWA bunch train
(20nC/bunch)
Euclid Techlabs LLC
value
148 MW
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Beam Test of the 26GHz Power Extractor
@ AWA Facility (May~June, 2009)
Load
Rf probe
16GHz
scope
11.424GHz BPF
(228MHz BW)
LO=14.576GHz
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
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Down-converted rf Trace of the
26GHz Power Extractor (4bunches)
Background noise
direct to the scope
11.44+14.576=26.016 GHz
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Down-converted rf Trace of the 26GHz Power
Extractor (16 bunches with 769ps separation)
4 bunches to reach
the steady state
11.44+14.576=26.016 GHz
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Charge Sweeping
Number is the percentage of
charge transmission out of the
structure.
•Theoretically, 9nC29.6MW, 24.8MV/m if σz=1.5mm.
•Calibration will be taken after the experiment.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
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.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Tuning/Nonlinear Effects in
Dielectric-Based Accelerator
forsterite
BST(M)
high intensity
wakefields in
nonlinear
structure
ε(E) for ferroelectric
dielectric composite
Euclid Techlabs LLC
Pulse steepening
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Tunable DLA
Temperature Tuning*
Temperature tuning
of 14 MHz/0K
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Tunable DLA
Fast DC Voltage Tuning
6 MHz at 20 kV/cm
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
New Ferroelectric
ε< 300, k> 10% in air
300
Lower dielectric constant,
higher tuning range
250
200
epsilon(0)
150
1.7
100
1.6
50
1.5
0
1_1
1.4
1_2
3_1
K
1.5
1.45
1.3
1.4
1.35
1.2
1.3
1.25
K
1.1
1.2
1
1.15
0
1
2
3
4
5
6
E, V/um
7 1.1
8
1.05
1
1
Euclid Techlabs LLC
3
95_1_1
95_1_2
95_3_1
95_3_2
95_5_1
3_2 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
5
5_2
8_1
8_2
2_1
2_2
4_1
4_2
6_1
6_2
7_1
7_2
серия 95
Kdc
Kpulse
Е=5В/мкм
8
2
серия 95
4
6
7
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
BST(M) Ferroelectric Based
L-band High Power Tuner
Collaboration with Omega-P and FNAL
30 ns
switching
speed
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Transformer Ratio
Transformer Ratio
R = (Max. energy gain behind the bunch) / (Max. energy loss inside the bunch).
30
W+
Wakefield , MV/m
20
10
0
-10
W-
R= W+ /W-
-20
-30
0
5
10
15
Distance behind the bunch, cm
20
25
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.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Ramped Bunch Train
+
W
+
W
(
z
)

zW
zW
d
Reference: Bane et. al., IEEE Trans. Nucl. Sci.
NS-32, 3524 (1985)

(
z
)
d
d
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 aLLC
separation of 10.5
Euclid
Techlabs
wavelengths of the fundamental mode
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Transformer Ratio
Experiment
two-bunch wakefield
experiment setup
Signal from the
field probe
(13.6GHz)
DLA
LO
(8.3GHz)
The field probe signal
from the RBT in the
13.625 GHz DLA
Signal to
the
digital
software
scope
(5.3GHz)
data
(13.6GHz)
6GHz digital scope
LO
(8.3GHz)
Wakefields measurements
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Leading and Tailing
8 nC and 20 nC bunches
the transformer ratio increases correspondingly, from R~ 1.8 to R~ 3.
satisfying
the requirement
of an equal
Euclid
Techlabs LLC
decelerating field inside each bunch
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
R>2 Experimentally Demonstrated.
C.Jing, A.Kanareykin, J.G.Power et al. PRL 98, 144801, 2007
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.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Intensity (arb. unit.)
Intensity (arb. unit.)
4 bunch Transformer
Ratio Experiments
40
30
20
10
0
time (ps)
10
20
30
40
40
30
20
10
0
10
20
30
+
W
40

(
z
)
time (ps)
zW
d
laser pulse stacking method to stretch the AWA
Techlabs
laser pulseEuclid
from FWHM
= 8 ps LLC
to 26.5 ps.
d
d
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Energy Modulated Bunch Train
Sequence of four bunches
550
500
450
400
350
300
250
200
150
100
50
0
-50
-100
-150
0
10
20
30
40
50
60
z, cm
70
80
90
100
110
Sequence of f our bunches
140
120
100
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
0
10
20
30
40
50
60
z, cm
70
80
90
100
110
A.Kanareykin et al, in preparation
For the same gradient: Ramped – 220 nC; Flat – 80 nC
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Energy Modulated Bunch Train.
Energy Distribution
Energy
(10-30-50-70) MeV Train
Sequence of four bunches
140
120
100
80
60
40
20
0
-20
-40
-60
-80
-100
-120
-140
0
10
20
30
40
50
60
z, cm
70
80
90
100
110
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.
A.Kanareykin et al, in preparation
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
Energy Modulation: pros and cons
Ramped Bunch Train
Pros:
- laser beam manipulation for the
train profile generation
Cons:
- lower accelerating gradient
- high charge for the last bunches
- transverse fields increase
- focusing for ramped bunch charges
A.Kanareykin et al, in preparation
Euclid Techlabs LLC
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
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009
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.
Euclid Techlabs LLC
ICFA Workshop on Novel Concepts
for Linear Accelerators and Colliders.
SLAC, July 7-10 2009