Shahin_Sanaye_Hajari
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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 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 3 mm RMS energy spread 0.530 MeV < 0.5 MeV 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 π§π = π§π + π 56 πΏπ πΏπ = πΏπ ⇓ πππ‘πππ’π =− ⇓ 2 π§π2 = π§π2 +2π 56 π§ π πΏπ +π 56 πΏπ2 π 56 π§π2 πππ = π§π2 − π§π πΏπ πΏπ2 π§π πΏπ πΏπ2 2 2 Optimisation of the magnetic chicane 2 Optimisation of the magnetic chicane 2.1 Bunch compression π§π − π§π = πΏ πΏ − πΏ 0 = π 56 πΏ + π566 πΏ 2 + π566 πΏ 3 4 2 Optimisation of the magnetic chicane 5 2 Optimisation of the magnetic chicane 2.1 Bunch compression Before chicane π 56 πππ‘πππ’π = −20.0 ππ βΉ 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 L πΏ = 330 − 20.0πΏ + 33.1πΏ 2 − 49.8πΏ 3 + π[πΏ Value 0.186 T 29.5 cm 70 cm 18.5o 4 3 Chicane and the injector overall performance 7 3 Chicane and the injector overall performance 3.1 Satellite population At P1 At P2 At P3 3 Chicane and the injector overall performance 7 3 Chicane and the injector overall performance 3.1 Satellite population π·2 βΆ π·2 + 40 ππ βΉ At P1 ππ‘πππππ‘π βΆ 2.6% βΆ 2.1% ππΏ : ∼ 10% β At P2 At P3 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 MeV) 40o off-crest ππΏ = 4.7 ππ ππ = 0.647 πππ 20o off-crest ππΏ = 5.5 ππ ππ = 0.553 πππ 3 Chicane and the injector overall performance 9 3 Chicane and the injector overall performance 3.3 Beam loss at chicane ππΏ : 10% β βΉ ππ < 1% πππ£ βΉ Beam loss at chicane: 4% βΆ 0.1% ππ πππ π 4 Fourth SHB 10 4 Fourth SHB 4.1 Satellite reduction motivation Satellite bunches: ο drive beam power efficiency. ο unwanted radiation βΉ 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 4SHB Cavity Distance to next cavity Voltage SHB1 255 (cm) 13 (kV) Cavity Voltage SHB2 145 (cm) 25 (kV) SHB1 15 (kV) SHB3 85 (cm) 35 (kV) SHB2 30 (kV) SHB4 50 (cm) 50 (kV) SHB3 45 (kV) Prebuncher 20 (cm) 45 (kV) Prebuncher 60 (kV) 3SHB 5 Conclusion 5 Conclusion οΌ 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: ο Satellite population reduction ο Beam loss reduction οΌ By using an additional SHB the Satellite population can be reduced to 1.0%. 12 Thanks for your attention. TW Buncher: Beam Loss Reduction Buncher parameter Beam parameter Value πΈπππ (ππ/π) 1.2 πΈπππ₯ (ππ/π) 5.7 L(cm) 147 P(MW) ~20 Value ππΏ (ππ) 7.23 ππ (πππ) 0.317 πππ£ (πππ) 2.38 Beam loss at magnetic chicane: βΆ π. π% Options for the Solenoid Channel: Emittance Growth
