thin film srf applications beyond accelerators · • thin film technology is mature • large area...

Thin Film SRF Applications beyond Accelerators

Norbert KleinForschungszentrum Jülich

Institut für Schichten und GrenzflächenD-52425 Jülich

Germany

Outline:

• Introduction

• Electrodynamic properties of superconducting thin films:new results on MgB2 and Nb

• Thin film based high-temperature superconductingresonators, filters and subsystems

• Cryogenic low-phase noise oscillators

• Millimetre wave / THz HTS Josephson devices: voltagestandard and Hilbert transform spectroscopy

• Summary and outlook

Overview: Microwave to THz applications of superconducting films

• Cavities for particle accelerators (Nb, Nb3Sn ?, NbN ?)

• Passive devices for wireless communications (YBCO, Tland Hg ? based cuprates)

• Detectors for mm wave and THz radiation (Nb, NbN,YBCO, MgB2 ? )

• Josephson voltage standards (Nb, YBCO ?)

• Josephson digital circuits (Nb, YBCO ?, MgB2 ?)

from Nature 424, 14. August 2003

Thin films for high-frequency applicationsREBa2Cu3O7 (Tc ≈ 90 K)

• thin film technology is mature

• Large area thin films commercially available, globalmarket leader is THEVA in Germany

from http://www.theva.com

1 10 10010-6

10-5

10-4

10-3

10-2

10-1

10

10

3

8

79

6

5

4

2

11

1

1

1

YBCO on LaAlO3 1 Lincoln Lab. 2 Siemens 3 Conductus/HP 4 FZ Jülich 5 NTT 6 Univ. Houston 7 Univ. Wuppertal 8 UCLA YBCO on MgO 9 RSRE YBCO on sapphire 10 FZ Jülich

77K

YBCO

Cu

surfa

ce re

sist

ance

[Ω

]frequency [GHz]

from http://www.theva.com

• d-wave nature of oxide high-temperature superconductors forbids exponential slope of Rs below Tc/2

⇒ no chance for accelerator applications

• Nonlinearities extremely sensitive to film quality because of shortcoherence length

from M. Hein, TU Ilmenau

Magnesium Diboride - new hope ?

Jun Nagamatsu et.al., Nature 410, 63 (2001)

1 2 3 4 5 6 7 810-2

10-1

100

101

102

103

Sample A Sample B NbN

Rsef

f (T)-R

seff (4

.2K

) (mΩ

)

Tc/T1 2 3 4 5 6 7 8

0.1

1

10

100

1000

∆π (0)/kTc=0.69λ(0)=82nm

Measurement Simulation

δλef

f (nm

)Tc/T

clear exponential dependences, but BCS fit to λ(T)reveals ∆/kTc between 0.7 and 1

B.B. Jin et al., Phys. Rev. B. 66, 104521 (2002)

0.0 0.2 0.4 0.6 0.8 1.00.0

0.5

1.0

1.5

2.0

∆π

∆σ

∆/kT

c

t

local limit: extract dynamic conductivity σ1(T) from Rs (T) and λ(T)employing

)()(21)( 3

12

02 TTTRs λσµω≈

0.0 0.2 0.4 0.6 0.8 1.00.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

S1210 S1211 Nb Simulation

σ 1/σ

n

t

Consequence of two-gap BCS model: coherence peak shifted to lower temperatures

B.B. Jin et al., accepted for Phys. Rev. Letters

1 2 3 4 5 6 7 8 9 10100

101

102

103

104

105

8nm 10nm 12nm 14nm 20nm 50nm 100nm 200nm

δλef

f (nm

)

T(K)0 50 100 150 200

80

120

160

200

240

280

Resonator Transmission Dirty limit

λ(0)

(nm

)d(nm)

High-precision λ(T) measurements on ultrathin niobium films

⇒ sensitive test of proximity effect generated by normalconducting surface of interface layers

B.B. Jin et al., publication in progress

[ ] )](/)(ln[)(/)(41)](/)([

)(00

2

2/100,

0 dldddldld

d L

πξξπξλ

λ−

=

Q factor of a resonator composed of dielectrics and metall wall segments:

G [Ω] ∝ V / λ03 : geometric factor

κ: filling factor of electric field energy in dielectric material (0 ≤ κ ≤ 1)

microstrip resonator: κ ≈ 1, G = 1 – 10 Ω

dielectric resonator: κ ≈ 1, G = 100 – 10000 Ω

tan1

0

δκ+=GR

Qs

from IMS_2002, Seattle, tutorial workshops

Technology for planar HTSresonators and filters


(a)

(d)

(e)

(b)

(c)

(a) quasi-lumped element

(b) micro strip(c) coplanar

waveguide(d) folded microstrip

with integrated capacitors

(e) 2D disk resonator

Planar HTS resonators

Q ≈ 104 _ 105 : attractive for filters (< 5 GHz)

from N. Klein and H. Chaloupka, Encyclopedia of Materials, Elsevier

Properties of HTS disk resonator

Current distribution of TM010 mode

Measured temperature dependence of Q0 (TM010 mode)


Devices

Q ≈105 - 106: attractive for surface impedance measurements of HTS films and low phase noise oscillators (5 to 30 GHz)

sapphire cylinder

HTS films

coupling loops

Puck TE01δ resonator with two HTS endplates

• measure Q(T) and f (T) of high Q resonance

• calculate surface impedance Zs (T) = Rs (T) + iωλL(T) of samplefrom Q(T) and f (T)

• Rs : surface resistance, determines losses

High-sensitivity microwave surface impedance measure-ment system for 7 to 20 GHz based on a sapphire dielectric resonator

N. Klein et al., Phys. Rev. Lett. 71, 2255 (1993), German and US Patent

sapphire puck

sc film

copper housing

coupling loops

Q ≈106 - 107: very attractive for mm wave low-phase noise oscillators (10 to 70 GHz)

Whispering gallery mode in a dielectric puck

Microwave resonator(resonant mode)with unloaded Q

adjacent resonatorcoupling

non-adjacent resonatorcoupling

coupling only between adjacent resonators ⇒ Chebyshev- type characteristic

additional coupling between non-adjacent resonators ⇒quasielliptic characteristic: damping poles at the passband edges ⇒ steeper skirts

Filters: resonator coupling schemes

∆f δf f

L(f)/insertion loss

dB

LsLs passband

filter skirt

1. N. Klein, H. Chaloupka, „Superconducting Microwave Applications: Filters“, Elsevier Encyclopedia of Materials: Science and Technology, ISBN: 0-08-043152-6, pp. 1-9 (2003)

⇒ high number of poles required for high performance filters

Filters: steepness of skirts

Q requirement to avoid rounding effects:

Chebyshev: β = 750Elliptic: β = 250

example:

δL =1 dB LS = 100dB δf = 1MHz ⇒Q0,min= 50.000 for elliptic filter

]dB[]GHz[

]MHz[]dB[ 0

min,0 Lf

fLQ s

δδβ≈

Filters: steepness of skirts

1. N. Klein, H. Chaloupka, „Superconducting Microwave Applications: Filters“, Elsevier Encyclopedia of Materials: Science and Technology, ISBN: 0-08-043152-6, pp. 1-9 (2003)

1.88 1.89 1.90 1.91 1.92 1.93 1.94 1.95 1.96 1.97 1.98-100

-80

-60

-40

-20

0

f [GHz]

|S21

| [dB

]

-50

-40

-30

-20

-10

0

|S11| [dB]


from Cryoelectra GmbH, Wuppertal

Sector of a basestation receiver frontend

Advantages of HTS / cryogenics

• higher receiver sensitivity due to reduction of filter insertion loss andlower noise temperature of LNA (rural areas)

• higher selectivity due to steeper filter skirts (crowded areas withstrong interference problems)

antenna preselect LNA mixer IF filter filter

IF

cryogenic environment LO

Enabling technology: cryocoolers

Compact, high-efficient, reliable, and low–cost cryocoolers required for most of the high-frequency applications

HTS subsystem developed by Cryoelectra GmbH, Germany with Stirling cooler developed at Leybold, Germany

Product information from Superconductor Technolgies http://www.suptech.com

Cryogenic oscillators•• P ideal carrier

carrier with phase noise

Doppler signal

f0 f0+fm f

• Doppler radar

• passive microwavefrequency standard

• high purity reference sources

+⋅+

+⋅=

PGFkT

ffQfL

mmLosc

αlog104

1log10 22

20

Leeson model: phase noise of a feedback oscillatorD.B. Leeson, Proc. IEEE vol. 54, pp. 329, 1966

f0, QL

G, F, α , T, P

tuneable cryogenic WG – resonator for f = 23 GHzProject with Bosch SatCom (Tesat-Spacecom), German Patent

• mechanical tuning range:50 MHz

• piezoelectric tuning range50 KHz @ 60 V

Extremely high Q0 ≥ 5 ⋅ 106 @ T = 77 KS. Vitusevich et al., IEEE-Transactions on Microwave Theory and Techniques 51, 163 (2003)

WG-resonator

HEMT amplifierHTS 2-pole dual-mode filter :

BW ≈ 0.5 %, IL ≈ - 1 dBsignaloutput

Cryogenic 23 GHz „near“ space qualified oscillator

S. Vitusevich et al., IEEE Transactions on Microwave Theory and Techniques 51, 163 (2003)

Cryogenic 23 GHz space qualified oscillator:phase noise far below that of conventional oscillators

SSB Phase Noise

-180

-160

-140

-120

-100

-80

-60

-40

-20

0

1,E+00 1,E+01 1,E+02 1,E+03 1,E+04 1,E+05 1,E+06 1,E+07

Offset / [Hz]

L(f)

/ [dB

c/H

z]

10MHz MO

mult. 10MHz MO

MMO 23GHz

SPLL_FETDRO+10MHz MO

S. Vitusevich et al., IEEE Transactions on Microwave Theory and Techniques 51, 163 (2003)

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

(b)

(a)

T=77Kf=93.37GHzΩ =1.2 ∆I1 = Ic

Voltage (mV)

Curr

ent

(mA

)

0.0

0.5

1.0

n = 0

∆In /

Ic

0.0

0.5

1.0

n = 1

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.5n = 3

Microwave current, a.u.

0.0

0.5

1.0

n = 2

AC Josephson effect in HTS bicrystal junctions

• Employ 1st Shapiro step to represent a dc/ac voltage withquantum accuracy ⇒ towards an HTS voltage standard

• Employ differential IV characteristic to deconvolute thespectral response of incident THz radiation ⇒Hilbert transform spectroscopy

Novel approach: quantum voltage standard in HTStechnology

Shunt (Au)

YBCO

Substrat(YSZ)

Korngrenze

L*

d m YBCO bicrystal junction with in-situ

gold shunt : RSJ like I/V charactersitic with small (5 %) spread of Rn

Fabrication of an array of bicrystal junctions by submicometer lithography

1.5 µm

grain boundary

Novel approach: quantum voltage standard in HTStechnology

Irradiation of microwaves by a coplanar waveguide

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

-10

-5

0

5

10

b)

a)

T=64K, Ic,min=0.3 mAR=0.066Ω, Vc=20µVf=32.05918 GHz, Ω=2.7

Vol

atge

(m

V)

Current (mA)

-50 -40 -30 -20 -10 0 10 20 30 40 50 60 70

-15

-10

-5

0

5

10

15 VJ, SINIS = 9.017999 mV∆V/VJ,SINIS=6x10-8

Diff

eren

ce v

olta

ge (

nV)

Current (µA)

A. M. Klushin, R. Behr, K. Numssen, M. Siegel and J. Niemeyer, APL, 80, p. 1972, 2002

First experimental demonstration for a giant Shapiro step in an HTS bicrystal array of 136 JJ with metrologically relevant accuracy

Laboratory prototype of an HTS voltage calibrator

Hilbert Transform Spectroscopy

Hilbert-Transform Spectrometers

Hilbert Spectroscopy of Coherent Transition Radiationin TESLA Test Facility Linear Accelerator at DESY

First measurements at DESY, 1997•Thermoionic gun, N =2.3x108 electrons•Macrobunch averaging•Bunch length measured by HTS: σz = 0.4 mm

Control room of the linac

Measurements at DESY, 1999, 2001•New Photoinjector, N =1.6x1010 electrons•Pulse response detection from a single bunch

Pulse response fromHT spectrometer

bunch of N electronsAl-foil

window

transitionradiation

Hilbert-spectrometer

100 150 200 2500

10

20

30

40

Gaussian fit σf=92 GHz

SPE

CTRU

M (ar

b.un

.)

FREQUENCY (GHz)

M. Geitz, K. Hanke, P. Schmueser, Y.Y. Divin, U. Poppe, V.V. Pavlovskii, V.V. Shirotov, O.Y.Volkov, M. Tonutti, DESY-TESLA Reports, 98-10 (1998).

Y.Y. Divin, U. Poppe, K. Urban, O.Y. Volkov, V.V. Shirotov, V.V. Pavlovskii, P. Schmueser, K. Hanke, M. Geitz, M. Tonutti, IEEE Trans. Applied Supercond.,1999, vol. 9, No.2, p.p.3346-3349.

M. Geitz, K. Hanke, P. Schmueser, Y.Y. Divin, U. Poppe, V.V. Pavlovskii, V.V. Shirotov, O.Y.Volkov, M. Tonutti, Proceedings 1999 Particle Accelerator Conf., New York, 1999 IEEE Publ , pp. 2178-2180

Summary and Outlook• Passive filters have found a niche market in mobilecommunication

• Extremely narrowband and tuneable (MEMS) HTS filtersare considered to be relevant for millitary applications

• Superconducting detectors are dominant for the THzrange:Nb SIS mixers: < 700 GHzNbN Hot electron bolometers: < 1.5 THz

• HTS grain boundary Josephson junctions have a hugepotential for millimetre wave and THz applications

thin film srf applications beyond accelerators · • thin film technology is mature • large area...

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