Design of the superconducting 350 MHz CH-prototype cavity

H. Liebermann, IAP FrankfurtTraining Course on Particle Accelerator TechnologyMol, Belgium, May 10.-11. 2007

Design of the superconducting 350 MHz

CH-prototype cavity

H. Liebermann, IAP Frankfurt

Institut für Angewandte PhysikLINAC AG

Training Course on Particle Accelerator TechnologyMol, Belgium, May 10.-11. 2007 2

Overview• Introduction• MicroWave Studio Simulations

– Endcell-Design (Radius and Length)– Girder-Height

• Electrical and magnetical peak-fields




H-Mode Family

IH-Strukture

4-vane RFQIH-RFQ

CH-Strukture

Interdigital H-Mode (IH)B E

++

-- Interdigital H-Mode (IH)BBB E

++

-- B E

++

++

--

--

Crossbar H-Mode (CH)BBB E

++

++

--

--

Crossbar H-Mode (CH)




Copper model




Endcell-Radius

0 100 200 300 400 500 600 7000,0

2,0x106

4,0x106

6,0x106

|Ez,

MW

S| [V/

m]

Position Strahlachse [mm]

Radius 170mm Radius 210mm Radius 250mm Radius 290mm

170mm




Endcell-Length-Variation(Copper-Model beta=0,2)

1654mm

Endlength=81,3mm

1794mm

Endlength=151,3mm

plus 70mm




Endcell-Length

0 200 400 600 8000,0

2,0x106

4,0x106

6,0x106

8,0x106

1,0x107

1,2x107

1,4x107

Ez,

MW

S [V/m

]

Position z-Achse [mm]

Länge 21,3mm Länge 61,3mm Länge 111,3mm Länge 131,3mm Länge 151,3mm

Kupfermodell beta=0,2

0 100 200 300 400 5000,0

5,0x106

1,0x107

1,5x107

2,0x107

E z,M

WS [V

/m]

Position Achse [mm]

Länge 5,65mm Länge 45,65mm Länge 105,65mm Länge 115,65mm Länge 145,65mm

Kupfermodell beta=0,1

Electric fields alongthe beam axis




Flatness and Frequency

0 20 40 60 80 100 120 140 160 180

-1

0

1

2

3

4

5

g/l = 0,5

(Een

d-Em

ittel)/E

mitt

el

Endrohrlänge [mm]

Kupfermodell beta 0,1 , r = 140mm Kupfermodell beta 0,2 , r = 170mm

0 20 40 60 80 100 120 140 160 180 200 220280

290

300

310

320

330

340

350

360

370

g/l = 0,5

Freq

uenz

[MH

z]

Endrohrlänge [mm]

Kupfermodell beta 0,1 , r = 140mm Kupfermodell beta 0,2 , r = 170mm




Variation of Girder-HeightCopper-model: beta=0,2 and radius=170mm

Girderheight=70mm Girderheight=0mm




Girder-Height

0 100 200 300 400 500 600 7000,0

2,0x106

4,0x106

6,0x106

|Ez,

MW

S| [

V/m

]

Position z-axis [mm]

Girder 0mm Girder 35mm Girder 70mm Girder 100mm

Copper model beta=0,2 , r = 170mm

0 10 20 30 40 50 60 70 80 90 100

340

345

350

355

360

365Copper model beta=0,2 , r = 170mm

Freq

uenc

y [M

Hz]

girder height [mm]

Electric field along beam axis

Frequency




Variation of the Girder-LengthCopper-model: beta=0,2 and Radius=170mm

Girder-Length=91% Girder-Length=100%

(Girderlänge 100% = 1360mm)




Girder-Length

0 100 200 300 400 500 600 7000

1x106

2x106

3x106

4x106

5x106

|Ez,

MW

S| [V/

m]

Position z-axis [mm]

91 Prozent 94 Prozent 97 Prozent 100 Prozent

Girderlength 100 Prozent = 1360mmCopper model beta=0,2 , r = 170mm

90 92 94 96 98 100

361,2

361,4

361,6

361,8

362,0

362,2

362,4

362,6

362,8

Freq

uenc

y [M

Hz]

Girderlength [%]

Copper model beta=0,2 , r = 170mm

Girderlength 100 Prozent = 1360mm




Endcell-Length-Variation(Prototype beta=0,1)

plus 95mm

928mm 1118mm

Endcell-Length=162,57mmEndcell-Length=67,57mm




Endcell-Length

0 100 200 300 400 5000,0

2,0x106

4,0x106

6,0x106

8,0x106

1,0x107

1,2x107

1,4x107

1,6x107

|Ez,

MW

S| [V

/m]

Positon z-axis [mm]

Length 117,57mm Length 137,57mm Length 147,57mm Length 157,57mm

Prototype-configuration beta=0,1

Electric field alongbeam axis

60 80 100 120 140 160 180

-1

0

1

2

3

4

5

Prototype beta 0,1 , r = 140mm

(Een

d-Em

ittel)/E

mitt

el

Endrohrlänge [mm]

g/l = 0,5

Flatness




0 2 4 6 8 10 12 14 16 18 200,30

0,35

0,40

0,45

0,50

0,55

0,60

Prototyp beta=0,1

g/l

Gap-Number

Prototype-structure with g/l-variation

Length = 1048mmRadius = 140mmbeta = 0.1




On-axis field and flatness

0 100 200 300 400 5000,0

2,0x106

4,0x106

6,0x106

8,0x106

1,0x107

1,2x107

|Ez,

MW

S| [

V/m

]

Positon z-axis [mm]

Length 120,7mm Length 130,7mm Length 140,7mmmit g/l-Variation

(beta=0,1)

120 125 130 135 140

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

1,0

1,2

(Een

d-Em

ittel)/E

mitt

el

endcell-length [mm]

Prototype beta 0,1 , r = 140mm Prototype beta 0,2 , r = 170mm

with g/l - Variation




Surface peak fields (prototype)

electric

magnetic




Stem-variation

b

a1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4 2 6 2 8

5 ,6

5 ,8

6 ,0

6 ,2

6 ,4

8 ,0

8 ,5

9 ,0

9 ,5

1 0 ,0

1 0 ,5

1 1 ,0

1 1 ,5

1 2 ,0

E peak

/Eac

c

s te m w id th b [m m ] (a = 2 1 .4 m m )

Bpe

ak/E

acc [m

T/M

V/m

]prototype: a=12.5mm , b=20mm




Drifttube-thickness

R1

R2 0 20 40 60 80 1000.0

5.0x106

1.0x107

1.5x107

2.0x107

2.5x107

3.0x107

E abs [

V/m

]

Position [mm]

R2 - R1

5 mm 7 mm 9 mm 11 mm

electrical field at the aperture fordifferent drifttube-thicknesses




electrical field at the surface of the drifttube with different thicknesses (5mm (left) und 11mm (right)) (ηpeak=0.9)




sc prototype gap

23.87max.13.94min.gaplength [mm]

mm857.422

=βλ

2mm

4βλ

R2-R1

y




min. & max. prototype gap

0,0 2,5 5,0 7,5 10,0 12,5 15,0 17,5 20,0 22,5 25,01,50x107

2,00x107

2,50x107

3,00x107

3,50x107

4,00x107

E abs [V

/m]

Position [mm]

R2 - R1

4 mm 5 mm 7 mm

Gap=13.94148mm

y0,0 2,5 5,0 7,5 10,0 12,5 15,0 17,5 20,0 22,5 25,0

1,50x107

2,00x107

2,50x107

3,00x107

3,50x107

E abs [V

/m]

Position [mm]

R2 - R1

4 mm 5 mm 7 mm

Gap=23.87280mm

y

Electrical field along y.

Variation of the drifttube-thickness




The prototype

178000(Ra/Q)G (Ω2)

155W (mJ/(MV/m)2)

352Frequency (MHz)

3.8E0 (MV/m)

3.7x108Q0 (total Rs=150 nΩ)

56G=RsQ0 (Ω)

3180Ra/Q (Ω) (T incl.)

3.0Ea=ET (MV/m)

19Ep (MV/m) @ Ea=3 MV/m

21Bp (mT) @ Ea=3 MV/m

1.5x109Q0 (BCS, 4.5K, 352 MHz)

0.1β

1048Length (mm)

19Gap number




Parts of the structure










at




superconductingCH-Prototype

RealCST MicroWaveStudio

Design of the superconducting 350 MHz CH-prototype cavity

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