MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Side Coupled Linac Design Side Coupled Linac Design at CERNat CERN

M. Pasini, Abingdon September 28th, 2005

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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CONTENTS:CONTENTS:

1. SCL structure2. Beam Parameters3. SCL Layout4. RF studies5. Frequency error study6. Conclusions

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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SCL PrinciplesSCL Principles

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Why SCL?Why SCL?

1. Above 90 MeV the effective Shunt Impedance of the SCL is bigger then the one of the CCDTL.

2. Compared to on-axis coupled structure (OCS) and/or annular-ring-coupled structure (ACS) the SCL offers a good mode separation in the coupling cell and simple and well established tuning procedure.

3. SCL cells can be easily machined on a lathe (using a circular frame) with tolerance within 0.05 mm in the nose cone region.

4. Alternative production technologies like Electrical Discharge Machining (EDM) (investigated by INFN-Naples) might reduce production costs.

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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ZTZT22 Curve Curve

0

10

20

30

40

50

60

0 20 40 60 80 100 120 140 160

Energy (MeV)

ZT2

(MO

hm/m

)

DTL tank1

DTL tank2

DTL tank3

CCDTLSCL

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Beam Parameters

Particle H-

Initial energy 90 MeVFinal energy 160 MeVBeam Intensity 40 mA (peak)Duty Cycle (LINAC 4)

0.08 %

Max Duty Cycle 14 %Frequency 704.4 MHzFocusing Channel

F0D0

n. acc. cells/tank

11 #

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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SCL Layout design SCL Layout design programprogram

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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SCL Layout design SCL Layout design programprogram

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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SCL LayoutSCL Layout

Klystron[#]

Tanks/Kly.[#]

Gradient E0

[MV/m]Power/Kly.

[MW]Energy[MeV]

N cells/tank[#]

1 5 4 3.00 107.42 11

1 5 4 3.06 125.16 11

1 5 4 3.15 144.16 11

1 4 (5)

4 2.59 (3.24)

160.2 (164.31)

11

Tot. Klystr.[#]

Tot. tanks[#]

Average Grad.[MV/m]

Tot. Power[MW]

Tot. Length.[m]

4 20 4 12.46 28.02

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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RF Studies with MWSRF Studies with MWS

Coupling and Shunt impedance study as a function of the intersection length

Geometric shapes of the coupling slot and hence coupling factors are well defined because each slot is re-machined

0%

1%

2%

3%

4%

5%

6%

0 10 20 30

d (mm)

K (%)

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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PSPICE SimulationPSPICE Simulation

±50 kHz error only on the accelerating cells

±50 kHz error on the accelerating and coupling cells

0.00%

0.05%

0.10%

0.15%

0.20%

0.25%

0.30%

0.35%

0% 2% 4% 6% 8%

k (%)

Error (%)STDEV

AVG

0.00%

0.10%

0.20%

0.30%

0.40%

0.50%

0.60%

0% 2% 4% 6% 8%

k (%)

Error (%)STDEV

AVG

For a complete module of 5 tanks we expect a maximum error of ± 0.9%

for the field level

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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704 MHz Klystrons704 MHz Klystrons

Contacts with 2 manufacturers :Thales – 4 MW single beam klystronToshiba – 5 MW multiple beam klystron Max pulse length = 2ms Rep rate = 50 Hz RF duty factor = 10 %

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Summary / ConclusionsSummary / Conclusions

1. A layout of the SCL section is completed.2. The new Excel tool allows to design SCL with a

variety of free parameters.3. Coupling coefficients of 3% guarantees low field

error (with 50 kHz tuning accuracy) with minimum reduction in Q-value.

4. Design for 2 klystrons meeting our specs are existing.