SLIDE 1
Outline
- ADMX-HF brief overview
- Cavity Characteristics
- Cavity study at Berkeley
- Future work
- Conclusion and summary
Application of the Bead Perturbation Technique to a Study of a - - PowerPoint PPT Presentation
Application of the Bead Perturbation Technique to a Study of a - - PowerPoint PPT Presentation
Application of the Bead Perturbation Technique to a Study of a Tunable 5 GHz Annular Cavity Nicholas Rapidis UC Berkeley Outline ADMX-HF brief overview Cavity Characteristics Cavity study at Berkeley Future work
SLIDE 2
SLIDE 3
Collaboration
Yale University (experim iment sit site)
Steve Lamoreaux, Ling Zhong, Ben Brubaker, Sid Cahn, Kelly Backes
UC Berkeley
Karl van Bibber, Maria Simanovskaia, Samantha Lewis, Jaben Root, Saad Al Kenany, Nicholas Rapidis, Isabella Urdinaran
CU CU Boulder/JILA
Konrad W. Lehnert, Daniel Palken, William F. Kindel, Maxime Malnou
LLNL
Gianpaolo Carosi, Tim Shokair
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Experiment at Yale
P
π‘πππππ β B2VQπ·πππ
- Cu Cavity with off-axis tuning rod
- 9 T magnet
- Dilution refrigerator T~100 mK
- Josephson Parametric Amplifier,
tunable from 4.4-6.4 GHz
- First data run (2016) in 5.75 GHz
range (~24 ΞΌeV)
SLIDE 5
Desired Cavity Characteristics
- Large Volume ~2 L
β 25.4 cm height β 10.2 cm diameter Use of 5.1 cm diameter copper rod
- Large dynamic frequency range
β 3.4 β 5.8 GHz
SLIDE 6
Desired Cavity Characteristics
- High Quality factor, Q
Q β
Modeβdependent constant of order 1 β Volume Surface area β(Skin Depth)
β Increases at lower temperature β Affected by rod position, coupling, intruder modes
SLIDE 7
Desired Cavity Characteristics
- High Form Factor, Cmnl
Cmnlβ‘
( d3π² π β πmnl
β
(π²))2 V d3π² π π² πmnl
β
(π²))
2
in our case π π² = 1 Non-uniformities in the cavity will cause mode localization thus deteriorating the form factor
SLIDE 8
Desired Cavity Characteristics
- Freedom from mode crossings
SLIDE 9
Desired Cavity Characteristics
- Freedom from mode crossings
SLIDE 10
Detailed Cavity Study at Berkeley
- Precision metrology on current apparatus
- High Fidelity Simulations
- Precision Field Mapping using Bead-Perturbation Technique
SLIDE 11
Detailed Cavity Study at Berkeley
- Precision metrology on central rod
β Alignment of rod axis w.r.t. tubes holding it in place in the cavity β Better understanding of mode localization when misaligned in cavity
- Precision metrology on cavity
β Allows for more accurate future simulations
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Detailed Cavity Study at Berkeley
- High Fidelity Simulations
TM010 TE
SLIDE 13
Detailed Cavity Study at Berkeley
SLIDE 14
Detailed Cavity Study at Berkeley
Sapphire bead Ξ΅=11.5
SLIDE 15
Detailed Cavity Study at Berkeley
Precision Field Mapping using Bead- Perturbation technique βΟ Ο = β(Ο΅ β 1) 2 VBead VCavity πΉ(π )2 πΉ(π )2
cav 1/2
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Determining mode type using bead pull
TM010 TE050
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Misalignment Measurements
SLIDE 18
Misalignment Measurements
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Misalignment Measurements
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Misalignment Measurements
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Misalignment Measurements
Each step corresponds to an angle shift of 1.5 mrad
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Mode Crossings
SLIDE 23
Mode Crossings
Data from TM010 mode no longer useful when mode is within ~3 MHz of TE mode
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Mode crossings
Other noticeable mode crossings have no significant effect on TM010 mode
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Future work
- Bead pull study on actual cavity
β Determining usable/unusable frequencies and impact of intruder modes β Ultimately, in situ bead-pull for real time characterization of the cavity and mode during the run.
- Full 3D mapping of cavity
- Simulations confirming behavior and studying further aspects of
cavity
β Free frequency ranges β New designs, e.g. Photonic Band Gap Cavities
SLIDE 26
Conclusion
- Can determine type of each mode in spectrum using bead
pull
- Good understanding of sensitivity to rod misalignments
- Ability to determine strength of mode crossings and
determine effect on data taking
SLIDE 27