Cavity tuning with dielectrics Daniel Bowring, Srinivasulu - - PowerPoint PPT Presentation

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Cavity tuning with dielectrics Daniel Bowring, Srinivasulu - - PowerPoint PPT Presentation

Apr 07, 2023 98 likes •287 views

Cavity tuning with dielectrics Daniel Bowring, Srinivasulu Gollapudi, Shashank Priya, Chiara Salemi, Andrew Sonnenschein, Alvin Tollestrup 2 nd Workshop on Microwave Cavities and Detectors for Axion Research 13 January 2017 Motivation

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SLIDE 1

Daniel Bowring, Srinivasulu Gollapudi, Shashank Priya, Chiara Salemi, Andrew Sonnenschein, Alvin Tollestrup 2nd Workshop on Microwave Cavities and Detectors for Axion Research 13 January 2017

Cavity tuning with dielectrics

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SLIDE 2

Motivation

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STO film dielectric

  • O.G. Vendik et al., J. Supercond. 12, 2 pp. 325-338 (1999).
  • Nonlinear dielectric films (e.g. strontium titanate, STO)

change permittivity with DC bias, temperature.

  • This can potentially be used for fine tuning of cavities.
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SLIDE 3

(1) Design & build coplanar waveguide resonator (2) Generate STO samples (3) Cryogenic resonator characterization (4) Tuning demonstration (5) 3D resonator demonstration

Outline of experimental program

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SLIDE 4

Coplanar waveguide resonator

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J.I. Marulanda et al., Micro. Opt. Technol. Lett. 53, 10 pp. 2418-2421 (2011).

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SLIDE 5

Coplanar waveguie resonator

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  • 3 mil Cu/Au traces
  • Rogers TMM10i dielectric
  • ~7 GHz fundamental mode
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SLIDE 6

CPWG spectrum

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SLIDE 7

Nonlinear dielectric films

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  • STO samples provided by S. Priya, S. Gollapudi at VA Tech.
  • Aerosol deposition, ~650 nm STO directly on quartz
  • Better quality/uniformity than previous films sputtered on

sapphire.

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SLIDE 8

After Annealing (S. Gollapudi)

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650 nm

Annealing condition: Annealed at 750°C/ 1h Heating rate 1°C/min Cooling rate 0.5°C/min

Shrinkage after annealing, ~ 13%

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SLIDE 9

Measurement setup (FNAL SiDet axion lab)

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LN2 VNA HVDC CPWG

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SLIDE 10

Measurement setup (FNAL Technical Division)

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  • Quantum Designs PPMS
  • 1” bore diameter
  • 1 K, 8 T
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SLIDE 11

PRELIMINARY PPMS testing (no bias)

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Warm sapphire Cold sapphire 77 K STO

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SLIDE 12

Quartz cryogenic performance (no bias)

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SLIDE 13

Current status

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  • We have a well-characterized resonator and multiple

cryogenic test options.

  • We have all required hardware in hand.
  • This includes a kV-class DC voltage supply with software

control and leakage current protection.

  • Measurement of film’s dielectric strength is possible.
  • Still needed: new samples with metallic coatings for DC bias

electrodes.

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SLIDE 14

Upcoming work

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  • Produce new samples with metallic coatings
  • Demonstrate electric tuning using current setup
  • Conceptual design for 3D implementation
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SLIDE 15

Supplemental slides

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SLIDE 16

Lab space for axion R&D at FNAL

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  • 26 GHz network analyzer & assorted microwave hardware
  • LN2 infrastructure
  • Clean room access
  • Engineering support
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SLIDE 17

Low temperature / high field facilities

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  • FNAL Technical Division magnet R&D lab:
  • LHe Oxford cryostat
  • 17 T solenoid, 68 mm bore diameter