CLIC_DDS 1st cell studies

Alessandro D’Elia

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Updates on Vasim CERN visit• Meeting with Walter Wuensch et al. • Suggested to chamfer the edges of the cell as it is

mechanically not possible to have sharp edges • Many discussions with Riccardo and me regarding

simulations: 1) The method of using ~ 200-300k mesh and solving zero order

solution is not accurate 2) When these results were compared to HFSS10 and CST

microwave, frequency was off by -30 MHz and H-field was higher by 15% i.e. 30 % more pulse temperature rise.

3) The better method is : Using surface approximation of ~2 micron and solving second order solution.

4) With this method now, results are consistent in HFSSv10, v12 and CST microwave.

5) Riccardo suggested a major change in cell geometry.

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a) b) c) 3

Hsmax(mA/m)

Eacc(V/m)

Hsmax/Eacc(mA/V)

1.817 0.3478 5.22

Zero order soln.180k mesh

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Eacc [V/m] Hsmax[A/m] Hs

max/Eacc[mA/(V/m)]

a 6.277e8 3.554e6 5.7

b 6.271e8 3.752e6 6

c 6.277e8 3.855e6 6.1

a) b) c)

Unphysical

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Hsmax(mA/m)

Eacc(V/m)

Hsmax/Eacc(mA/V)

1.817 0.3478 5.65

Second order soln.

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Zero order slon.F=11.9682 GHz

Hsmax(mA/m)

Eacc(V/m)

Hsmax/Eacc(mA/V)

2.0841 0.41 5.04

New geometry : Riccardo

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First order soln.F=11.9897 GHz

Hsmax(mA/m)

Eacc(V/m)

Hsmax/Eacc(mA/V)

1.7 0.32 5.38

Order of Soln.

facc Hsmax(mA/m)

Eacc(V/m)

Hsmax/Eacc(mA/V)

Zero 11.9682 2.0841 0.41 5.04

First 11.9896 1.7 0.32 5.3

Second 11.9896 1.6 0.285 5.61

SecondHigher mesh

11.9895 1.6 0.31 5.16

Mixed 11.9847 2.17 0.41 5.29

HFSS v 12 results with a modified geometry

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Freq (GHz) Eacc [V/m] Hsmax[A/m] Hs

max/Eacc[mA/V]

CST 11.9853 6.2413e8 2.99884e6 4.8

HFSSv10 11.9913 0.464 2.25e-3 4.8

CST

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HFSSv10

Freq (GHz) Eacc [V/m] Hsmax[A/m] Hs

max/Eacc[mA/V]

a 11.9912 0.4422 2.213 4.8

b 11.9913 0.464 2.25e-3 4.8

a

b

HFSSv10

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Freq (GHz) Eacc [V/m] Hsmax[A/m] Hs

max/Eacc [mA/V]

CST 12.026 1.2758e9 3.37729e6 2.6 (3.65 with 120 phase)

HFSSv10 12.029 0.708 1.88e-3 2.7 (3.65 with 120 phase)

HFSSv12 12.031 0.68 1.85e-3 2.7 (3.64 with 120 phase)

SF 12.029 1.5e6 3967.52 2.6

SF

HFSSv10

HFSSv12CST

Undamped: comparison

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CLIC_G vs CLIC_DDS

3.2Eacc

Hmaxsur

5.0Eacc

Hmaxsur

CLIC_G CLIC_DDS

3.65Eacc

Hmaxsur

5.65Eacc

Hmaxsur

Undamped

Damped

Undamped

Damped 1.56 1.55?

@ 4.0 mm iris radius

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The difference between undamped

Eacc

Hmaxsur and

dampedEacc

Hmaxsur

is due to the circular shape breaking when the coupling waveguide are inserted. Therefore the basic idea is to move up the coupling cell in order to minimize this effect and then, to optimize the joint curvature between the coupling and the cell to better distribute the field

Facc = 12.53 GHz Facc = 12.97 GHz

2ε 1ε

2ε 1ε

H=5.0 mm H=5.0 mm

H = 2.5 mm H = 2.5 mm

H= Full width of the manifold

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3.33ε

4.35 mA/V

0.6 V/m

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2.7A/m2.7A/m3.4

Eacc

Hmaxsur

3.4Eacc

Hmaxsur

8.3Eacc

Hmaxsur

4Eacc

Hmaxsur

High meshLow mesh

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ab

c

2.1mA/m

ab

c

1.8mA/m

28.4Eacc

Hmaxsur

Low meshHigh mesh

24.4Eacc

Hmaxsur

27.4Eacc

Hmaxsur

23.4Eacc

Hmaxsur

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Final table

Freq (GHz)Hs

max/Eacc [mA/V]Line

Hsmax/Eacc [mA/V]

Color label

CST

Low mesh 11.9834 4 4.3

High Mesh 11.9869 3.8 4.3

HFSSv10

Low mesh 11.9918 4.24 4.28

High Mesh 11.9913 4.23 4.27

HFSSv12 - 11.9927 4.35

NEXT• Check Aleksej undamped structure• Inclusion of real manifold geometry• Dipole simulations• Studying the effect of major geometric change in

the manifold coupling• If everything will be successful (as we believe),

review the general parameters in order to be more competitive with respect to CLIC_G (e.g. Relaxing the thermal heating and/or reviewing the beam current parameters to have higher efficiency....)

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