MP - HIPPI General meeting, Abingdon October 28-30, Side Coupled Linac Design at CERN Side Coupled Linac Design at CERN M. Pasini, Abingdon September 28 th, 2005

MP - HIPPI General meeting, Abingdon October 28-30, CONTENTS: 1. SCL structure 2. Beam Parameters 3. SCL Layout 4. RF studies 5. Frequency error study 6. Conclusions

MP - HIPPI General meeting, Abingdon October 28-30, SCL Principles

MP - HIPPI General meeting, Abingdon October 28-30, 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, ZT 2 Curve DTL tank1 DTL tank2 DTL tank3 CCDTL SCL

MP - HIPPI General meeting, Abingdon October 28-30, Beam Parameters ParticleH-H- Initial energy90MeV Final energy160MeV Beam Intensity40mA (peak) Duty Cycle (LINAC 4) 0.08% Max Duty Cycle14% Frequency704.4MHz Focusing ChannelF0D0 n. acc. cells/tank11#

MP - HIPPI General meeting, Abingdon October 28-30, SCL Layout design program

MP - HIPPI General meeting, Abingdon October 28-30, SCL Layout design program

MP - HIPPI General meeting, Abingdon October 28-30, SCL Layout Klystron [#] Tanks/Kly. [#] Gradient E 0 [MV/m] Power/Kly. [MW] Energy [MeV] N cells/tank [#] (5) (3.24) (164.31) 11 Tot. Klystr. [#] Tot. tanks [#] Average Grad. [MV/m] Tot. Power [MW] Tot. Length. [m]

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

MP - HIPPI General meeting, Abingdon October 28-30, PSPICE Simulation ±50 kHz error only on the accelerating cells ±50 kHz error on the accelerating and coupling cells 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, MHz Klystrons Contacts with 2 manufacturers : Thales – 4 MW single beam klystron Toshiba – 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, Summary / 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.