CLIC Drive Beam Injector Design Update Shahin Sanaye

CLIC Drive Beam Injector Design Update Shahin Sanaye Hajari 1. Institute For Research in Fundamental Sciences (IPM), Tehran, Iran 2. CERN, Geneva, Switzerland

Contents 1. Injector layout and the latest results 2. Optimisation of the magnetic chicane 3. Chicane and the injector overall performance 3. 1 Satellite population 3. 2 Beam loss at chicane 4. Fourth SHB

1 Injector layout and the latest results 1. 1 Injector Layout 1

1 Injector layout and the latest results 2 1 Injector layout and the latest results 1. 2 Latest results Transverse Longitudinal Parameters Current value Target value RMS bunch length 3 mm RMS energy spread 0. 530 Me. V < 0. 5 Me. V Satellite population 2. 6% As less as possible 35 mm-mrad <100 mm-mrad 530 gauss As small as possible Normalised emittance Average solenoidal field Beam loss at chicane: 4%

2 Optimisation of the magnetic chicane 3 2 Optimisation of the magnetic chicane 2. 1 Bunch compression

2 Optimisation of the magnetic chicane 2. 1 Bunch compression 4

2 Optimisation of the magnetic chicane 5 2 Optimisation of the magnetic chicane 2. 1 Bunch compression Before chicane After chicane Bunch length reduction: ~ 20 %

2 Optimisation of the magnetic chicane 6 2 Optimisation of the magnetic chicane 2. 2 Transvers plane and chicane parameters Parameter Dipole field Dipole length Drift length Bending angle Value 0. 186 T 29. 5 cm 70 cm 18. 5 o

3 Chicane and the injector overall performance 7 3 Chicane and the injector overall performance 3. 1 Satellite population At P 1 At P 2 At P 3

3 Chicane and the injector overall performance 8 3 Chicane and the injector overall performance 3. 2 Bunch length and energy spread correlation After first accelerating structure (6 Me. V) 40 o off-crest 20 o off-crest

3 Chicane and the injector overall performance 3. 3 Beam loss at chicane 9

4 Fourth SHB 10 4 Fourth SHB 4. 1 Satellite reduction motivation Satellite cleaning system Model CDR version Current model 4 SHB Satellite population 4. 9% 2. 1% 1. 0% Number of SHB 1 2 3 4 Satellite population ~14% ~5% ~2% ~1%

4 Fourth SHB 11 4 Fourth SHB 4. 2 Sub-harmonic bunching system parameters 4 SHB Cavity Distance to next cavity Voltage SHB 1 255 (cm) 13 (k. V) Cavity Voltage SHB 2 145 (cm) 25 (k. V) SHB 1 15 (k. V) SHB 3 85 (cm) 35 (k. V) SHB 2 30 (k. V) SHB 4 50 (cm) 50 (k. V) SHB 3 45 (k. V) Prebuncher 20 (cm) 45 (k. V) Prebuncher 60 (k. V) 3 SHB

5 Conclusion ü By optimising the magnetic chicane to act as a bunch compressor as well as phase space cleaner the allowed bunch length at the end of injector will be 20% longer. This results in: Ø Satellite population reduction Ø Beam loss reduction ü By using an additional SHB the Satellite population can be reduced to 1. 0%. 12