Ferroelectric Based Technologies for Accelerators

AAC’08 Santa Cruz CA, July 27th - August 2nd

2008

Ferroelectric Based Technologies forAccelerators

A.Kanareykin Euclid TechLabs LLC, Rockville, MD

This work is supported by

the DOE, High Energy Physics

AAC’08, Santa Cruz CA, 2008


2008

A.Kanareykin, Euclid TechLabs LLC, Rockville, MD S.Kazakov, KEK, Tsukuba, Japan/Omega-P Inc., CT

E. Nenasheva, Ceramics Ltd., St. Petersburg, Russia, A.Tagantsev, EPFL, Lausanne, Switzerland

V.Yakovlev, Fermi National Lab

PROJECT IN COLLABORATION WITH YALE/OMEGA-P, INC., FNAL, ORNL/SNS, ELTECH

UNI. and ANL/AWA

TEAM


2008

Outline

BST(M) ferroelectric: ultra fast switching material

Properties required for the accelerator applications

Material development: what have been done

Large diameter bars/rings fabrication

Testing by Omega-P, Inc.; L, X and Ka band designs

Parallel and transverse biasing field

Summary


2008 4

Ferroelectric Rings

A concept of phase shifter design (Omega-P, Inc.)


2008

Applications of tunability

- Telecommunications - power - mW - W

- Radars - power - W - kW

- Accelerator technique - power - (0.5 -200) MW

Materials development

for the US Department of Energy


2008

Applications of Ferroelectricsin Accelerator Technique

- RF tuning at X-band/Ka band

- RF tuning at L-band

- Fine tuning of dielectric structures

Tuning speed

low

10-20 ns

10-20 μs


2008

Requirements

- Permittivity

- Relative tunability

- Tuning dc field

- Loss tangent (10 GHz)

- Commutation time

- Size of elements

kV/cm5010

500300

%2010

cm105.0

20 ns - 20 μs

< 3× 10-

3 f/tanδ ~ const !


2008

FERROELECTRIC PROPERTIESFOR ACCELERATOR APPLICATIONS

- The dielectric constant should not exceed 300-500 to avoid problems caused by interference from high-order modes and extra wall losses.

- The dielectric constant should be variable by 15-20% to provide the required switching and tuning properties.

- Bias electric fields required to adjust the permittivity within this range should be reasonable, ~few 10’s of kV/cm - The loss tangent should be in the range of few10-3 or lower at 11-34 GHz to allow switching at 120-180 Hz rep rate.


2008

FERROELECTRIC PROPERTIES

- very short intrinsic response time of ~10–10 - 10-11 sec ( 1 ns for circuits)

- high dielectric breakdown strength of 150-200 kV/cm

- high vacuum compatibility

- easy mechanical treatment (similar to conventional ceramic)

Ferroelectrics should have the following properties to operate in high-power rf switching and tuning devices:

- - 300-500 [500-600 current, recently reduced to 200-250]- variation - 10% - 20% at 50 kV/cm, [15% - E┴, >30% E║]- DC field - 10’s of kV/cm loss [20-60 kV/cm tested]- tanδ~10-2-10-3 at 11-35 GHz [5×10-3 at X-band, 5 – 10 ×10-4 700 MHz ]


2008

Tuning of permittivity in ferroelectrics

dcE

RFE

)0(

)(

E

n

)0(

)()0(r

En

For small tuning (nr<<1)

3r )0(n

Ferroelectrics !!!

1)0(


2008

Choice of material and approach

Composite: (Ba,Sr)TiO3 + dielectric (bulk ceramics)

0

500

1000

1500

2000

0 0.2 0.4 0.6 0.8 1

q

0

0.005

0.01

0 0.2 0.4 0.6 0.8 1

tan

q

(i) Use of BST with high 3

r )0(n

Spherical inclusion composite

(ii) Dilution with dielectric

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.2 0.4 0.6 0.8 1

q

)0(

)()0(

E

nr


2008

MgO and Mg2TiO4

additives

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

0 0.1 0.2 0.3 0.4 0.5concentration of inclusions, q

nreff

/nr

1

2

3

3D – theory

2D – theory

periodicnumericalsolution

Dependence permittivity ε′ (a), temperature Tm (b) and tunability kt for the samples BST (55/45) wt.% MgO (1) and Mg2TiO4 (2)


2008

Ferroelectric properties vs. frequency and % wt of inclusions

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.2 0.4 0.6 0.8 1

q

Content of

Mg2TiO4,

% wt.

f =1 MHz

Qf ,GHz

Ku

( E,

2V/m) tan

15.0 460 0.00021 1200-1300 1.11

20.0 507 0.00031 1200-1300 1.08

30.0 375 0.00024 1100-1300 1.09

40.0 290 0.00025 1100-1150 1.1155 %BaTiO3 - 45%.SrTiO3 with 20% МgO


2008

Developed materials

GHz10f

600500 kV/cm20dc E

(Ba,Sr)TiO3 based composite

(%)rn

Sengupta et al(patents)


2008

BST(M) Ferroelectric: Size Effects

Dimension studies for the BSM-3 (left) and BSM-4 (right) ferroelectric samples with thickness of 0.1 – 0.5 mm.


2008

BST(M) Ferroelectric: Bulk Sample Measurements

(Omega-P, Inc.)


2008

Experimental Setup, ns Scale Switching Time

Pictures of the experimental setup for the time response testing of the

ferroelectric samples to high pulse voltages.

time,s

-10x10-9 -5x10-9 0 5x10-9 10x10-9 15x10-9 20x10-9

Uco

ntro

l(V)

0

500

1000

1500

2000

2500

3000

time,s

-10x10-9 -5x10-9 0 5x10-9 10x10-9 15x10-9 20x10-9

Ud(

mV

)~C

-15.0

-12.5

-10.0

-7.5

-5.0

-2.5

0.0


2008

Various Samples of BST(M)

Various Samples of BST(M)

DC and Pulse Tunability Measurements

Kdc =C(0)/C(Udc )=C(0)/Cdc corresponds to capacitance value Cdc measured in 1 min after themoment of Udc switching on).

Kdyn =C(0)/Cpulse (Um) =C(0)/Cpulse Cpulse corresponds to the end of the leading front of the 20 ns pulse.

×10 kV/cm

×10 kV/cm


2008

FAST ACTIVE X-BAND HIGH POWER PHASE SHIFTER

* Developed by Omega-P, Inc.

S. Kazakov et al “First Measurements of RF Properties of Large Ferroelectric Rings "

dcRF EE

Ferroelectric ring elements for the X-band high power phase shifter. The same technology will be used for the L-band tuner fabrication.


2008

Loading with parallel bias

dcRF EE

Ferroelectric L-band Reflecting Phase Shifter

RF field, TEM mode

dc field

Copper electrodes

ferroelectric ring

* Developed by Omega-P, Inc.


2008

L-band Planar Design (Omega-P, Inc.)

S. Kazakov et al. EPAC’08* Developed by Omega-P, Inc.

dcRF EE


2008

Problem of transverse bias

d

3d

dcE

RFE

dcRF EE


2008

BST(M) ferroelectric group of compositions

composition ε tanδ×10-3, 10 GHz Kparallel, 4 V/μ Ktransverse, 4 V/μ

BSM-1 ~520 4.0 1.16 1.08 BSM-2 ~420 3.4 1.08 1.05 BSM-3 ~580 5.0 1.27 1.16 BSM-4 ~600 8.7 1.50 1.22

E.Nenasheva. “Development of A Low Loss Microwave Ferroelectric Material for the High Power Tunable Devices”


2008

Effect of dc bias orientations

longitudinal transverse

E

acE

EACE

)0(

)(

E

n ?n


2008

Examples: nvs n

Edc, kV/cm

n (E)

1

2

3

0 5 10 15 20 251

1.5

2

2.5

3

kV/cm,E

3

2n

n

n

n

(Ba0.65Sr0.35)TiO3 at 3150K ; data by Daimond (1961)

1

2

3

n (E)

Edc, kV/cm

0 5 10 15 201

1.2

1.4

1.6

kV/cm,E

n

n

3

2n

(Ba0.8Sr0.2)TiO3 at 333 0K data by Pertov et al (1971)

n

Acceptable loss of tunability when passing from n‖ to n┴


2008

BST(M): what have been done ?

The group of materials have been developed: from BSM-1 to BSM-4 Pulse measurements have been carried out : < 10 ns switching time !

Theory of the BST(M) composite ferroelectric have been developed

Transverse dc bias feasibility has been demonstrated

Dielectric response and tunability have been measured/mechanical

Dimension effects have been studied

Metallization technology has been developed

First direct BST bulk sample measurements

First cold test of the L-band fast shifter: 1200 phase shift

Tunable DLA structure cold test : temperature and dc bias tuning


2008

to be done:

- Material improvement with lower loss tangent

(Euclid)

- Vacuum testing (Euclid/ANL)

- High power testing at X-band (Omega-P/NRL)

- Beam testing of the tunable DLA (Euclid/ANL)

- Fast switching of the L-band phase shifter (Omega-

P)

BST(M): what will be done ?

XI-Electroceramics, Manchester, UK August 31, 2008

Ferroelectric Based Technologies for Accelerators

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