Planned Breakdown Test of SW Accelerator Cavity with Shaped Iris

J.M Neilson, V. Dolgashev and S. Tantawi

SLAC National Accelerator Laboratory

IWLC 2010Geneva

Outline

• Previous breakdown results for elliptical and rounded iris

• Calculations for shaped iris geometry

Two Single-Cell-SW Structures with same magnetic but different electric fields

Thick elliptical iris

Thin round iris

1C-SW-A3.75-T1.66-Cu 1C-SW-A3.75-T2.0-Cu

Thin round irisThick elliptical iris

Parameter Values for Simple Iris(Field Normalized for 100MeV/m Gradient)

Parameter T=1.66 Round Iris

T=2.6mmElliptical

Iris

Stored Energy [J] 0.189 0.189

Q-value 8820 8560

Shunt Impedance [MOhm/m] 85.2 82.6

Max. Mag. Field [KA/m] 314 325

Max. Electric Field [MV/m] 266 203

Losses in one cell [MW] 1.54 1.59

Hmax*Z0/Eacc 1.18 1.22

Max. Im{E x H*} W/µm2 42.8 44.4

Max. Im{E x H*}/H2 417 407

Breakdown Dependence

8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 2 0 0 2 2 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

G rad ien t M V m Bre

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a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak Elec tr ic F ield M V m Bre

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a 0.215, t 4.6mm, K EK 4a 0.143, t 2.6mm, SLA C 1a 0.105, t 2.0mm, SLA C 1

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak M ag n etic F ield k A m Bre

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a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak P u ls e Heatin g d eg . CBre

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a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak Elec tr ic F ield M V m Bre

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a 0.143, t 1.66mm , K EK 1a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak M ag n etic F ield k A m Bre

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y1pulsemeter a 0.143, t 1.66mm , K EK 1

a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

P eak P u ls e Heatin g d eg . CBre

akd

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nPro

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eter

a 0.143, t 1.66mm , K EK 1a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

8 0 1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 2 0 0 2 2 01 0 7

1 0 6

1 0 5

1 0 4

1 0 3

1 0 2

1 0 1

1 0 0

G rad ien t M V m Bre

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a 0.143, t 1.66mm , K EK 1a 0.215, t 4.6mm , K EK 4a 0.143, t 2.6mm , SLA C 1a 0.105, t 2.0mm , SLA C 1

thin round iris

thick elliptical iris

thin round iris

thick elliptical iris

1C-SW-A3.75-T2.6-Cu 10 MW input

Resonance at 11.4212 GHz β = 0.988

Maximum magnetic field 672 kA/m Maximum magnetic field 390 MV/m

V.A. Dolgashev, 25 September 2007

1C-SW-A3.75-T2.2-Cu 10 MW input

Resonance at 11.424 GHz β = 1.007

Shaped Iris

Thick elliptical iris Thin round iris

- Iris profile designed to maximize shunt impedance, minimize peak surface magnetic field

Parameter T=1.66 Round Iris

T=2.6mmElliptical

IrisT=2.2mm

Shaped Iris

Stored Energy [J] 0.189 0.189 0.186

Q-value 8820 8560 10090

Shunt Impedance [MOhm/m] 85.2 82.6 99.2

Max. Mag. Field [KA/m] 314 325 294

Max. Electric Field [MV/m] 266 203 268

Losses in one cell [MW] 1.54 1.59 1.32

Hmax*Z0/Eacc 1.18 1.22 1.11

Max. Im{E x H*} W/µm2 42.8 44.4 56.5

Max. Im{E x H*}/H2 417 407 650

SW Cells a/λ =0.143, π Phase ShiftField Normalized for 100MeV/m Acceleration

Summary

• New structure designed with lower magnetic field

• However local Poynting vector significantly increased compared to other structure