artificial material design for high power...

Artificial Material Design for High Power

ApplicationsMs Aimée Hopper

Prof. Rebecca Seviour

International Institute for Accelerator Applications

University of Huddersfield

aimee.hopper@hud.ac.uk

ESRF 75KWSolid State RF

Hughes TWT RF Tube 100kW

Aimee.Hopper@hud.ac.uk

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New vs Old

Material ClassificationsAimee.Hopper@hud.ac.uk

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What is an Artificial Material?Aimee.Hopper@hud.ac.uk

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E=0 E E

𝐷 = 𝜖0𝐸 + 𝑃 = 𝜖𝐸

𝐵 = 𝜇0𝐻 +𝑀 = 𝜇𝐻Constitutive

Relations

Electrons

Block of Material

Nucleus

Artificial Media

• Effective Permittivity • Effective Permeability

TWT – High Power RFAimee.Hopper@hud.ac.uk

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ElectronBeam

RF in

RF Out

h

p

Δh

Phase ConstantY. S. Tan and R. Seviour, EPL (Europhysics Letters),

Volume 87, Issue 3 (2009)http://arxiv.org/abs/1003.5401

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𝛼 =1 − 𝑆11

2 + 𝑆212

2𝑆21

𝑛 =1

𝑘𝑑𝑐𝑜𝑠−1(𝛼)

𝑧 = −1 + 𝑠11

2 − 𝑠212

1 − 𝑠112 − 𝑠21

2

𝜀 = 𝑛/𝑧

𝜇 = 𝑛𝑧Sm

ith, D

. R

., e

t al., P

hys.R

ev. B

65.1

9 (

2002)

Experimental Results

𝜇

𝜖

Loaded WaveguideAimee.Hopper@hud.ac.uk

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Temperature [°C]

High Power Design – Infinite System

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Aimee.Hopper@hud.ac.uk

• Simulations in HFSS

• Bloch-Floquetboundary conditions

• Infinite sheet of unit cells

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Interaction at 9.9GHz|𝑆𝑖𝑗|

S11

S21

𝜇

𝜖

Frequency Dependence of 𝑆11, 𝑆21, 𝜖 and 𝜇

Frequency Dependence of Dispersion and Loss

Loaded Waveguide

• Waveguide Ports

• PEC boundaries

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Magnitude of 𝑆𝑖𝑗 comparing the infinite

system (dotted) to the loaded waveguide

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𝑆𝑖𝑗 and 𝜖 and 𝜇

vs Frequency

Loaded Waveguide|𝑆𝑖𝑗|

S11

S21

𝜖

𝜇

COMSOL Thermal SimulationsAimee.Hopper@hud.ac.uk

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• 1kW 20 secs at 9.64GHz

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Larger Loaded Waveguide

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Larger Loaded Waveguide𝑆 𝑖𝑗

Frequency Dependence of

𝑆𝑖𝑗 , 𝜖 and 𝜇Dispersion and Loss

Frequency [GHz]

S11

S21

𝜖

𝜇

COMSOL Thermal SimulationsAimee.Hopper@hud.ac.uk

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• 1kW 20secs, 10.14GHz

Dispersion and Loss

Future Work…

• Particle In Cell Simulations • MAGIC

• Fabricate Structure• Non Trivial

• Cold testing at Low Power

• Hot testing with electron beam

• Hot testing with High Power RF

Aimee.Hopper@hud.ac.uk

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Conclusions

• Existing designs of artificial materials can have issues handling high power.• This only gets worse as number of unit cells in the

system increases.

• Engineered a unit cell which enables an interaction with a low power electron beam.

• Engineered a unit cell which exhibits low loss.

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Thanks

Spare Slide 1:More Unit Cells Aimee.Hopper@hud.ac.uk

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Spare Slide 2: DispersionAimee.Hopper@hud.ac.uk

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