Dielectric Donut Final Design B. Freemire IIT HPRF/HCC Design - - PowerPoint PPT Presentation

Dielectric Donut Final Design

• B. Freemire

IIT HPRF/HCC Design Meeting August 27, 2014

8/13/14

• B. Freemire - HPRF/RF Breakdown

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Quotes

• Accuratus – No
• Morgan – Largest parts they

make are 8” in diameter, can get one from sister companies; solid disk $1,200

• $1,500
• Coorstek – 1 piece for $1,800, 2 pieces for $2,500, 10 week lead time

–

I received a sample piece today (99.5%)

–

Offer 85, 90, 94, 96, 98.5, 99.5, 99.8 & 99.9% alumina

8/13/14

• B. Freemire - HPRF/RF Breakdown

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CoorsTek AD-995

• Specs:

– εr = 9.81 (σ = 0.01) – tan δ = 7x10-5 (σ = 5x10-6) – Above measured at 5 GHz – Dielectric strength = 8.7 MV/m

• This dielectric constant requires changing

Frank's donut's dimensions

8/13/14

• B. Freemire - HPRF/RF Breakdown

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Donut Simulations

εr = 9.0, f =799.31 MHz εr = 9.81, f = 794.55 MHz Teflon Alumina 100 atm H2 Gaskets

8/13/14

• B. Freemire - HPRF/RF Breakdown

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Donut Criteria

• Dimensions of ring will have to be tweaked slightly
• I will aim for a “high” frequency

–

Easier to bring down frequency of cavity

• Teflon spacers are arbitrary

–

Making them smaller is one way to bring up frequency

• Variation in εr effect on frequency to be investigated
• Frank's thermal calculations show heating not an issue

8/13/14

• B. Freemire - HPRF/RF Breakdown

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“Easier” Geometry

• I've been looking at an insert geometry that would be simpler to machine
• Approaching optimal dimensions

20 atm H2 f = 806.59 MHz 100 atm H2 f = 800.65 MHz

8/13/14

• B. Freemire - HPRF/RF Breakdown

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Plan

• Take measurements of sample provided by

Coorstek this week

• Finalize dimensions of approved geometry
• Order 2-3 pieces of varying purity next week