1. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Laser system schematic 22 44 1.55  s 200  s, 5-50 Hz 15 kW 10  J 270  s ~2332 pulses 370 nJ/pulse ~2332 e - bunches 2.33 nC/bunch Beam conditioner 1.5 GHz Nd:YLF oscillator 400  s, 5-50 Hz Diode pump 18 kW pk 3 kW 2  J 3-pass Nd:YLF amplifier x300 CW preamp 3 pass Nd:YLF amplifier x5 200  s, 5-50 Hz Diode pump 22 kW pk Optical gate (Pockels cell) Energy stabiliser (Pockels cell) Feedback stabilisation Phase coding

2. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Practical layout High Q preamp High Q oscillator Coding Faraday isolator Amp 1 Amp 2 1.54  s slicing Noise control 1 pulse slicing HG Thermal lensing correction 300 cm

3. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Amplifier head design Laser head assembly Nd:YLF rod 7mm diameter 8 cm long – Amp. 1 10 mm diameter 11 cm long – Amp. 2 1% doping level Deep surface etching for higher fracture limit Glass tube The rod water Diodes Lens 5 Diode laser stucks 18 kW total peak power – Amp. 1 22 kW total peak power – Amp. 2 400  s – Amp.1 200  s – Amp.2

4. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Amplifier 1 Amp 1 operational and tested at 5 Hz and 50 Hz Rod failure at 50 Hz may be due to non-saturated operation Expected output has been delivered (actually slightly exceeded) Near-field uniformity should improve with better rod

5. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Amplifier 1 Near-field profile is flattened by saturation but shows some effects of rod inhomogeneities Measured output from Amp 1 exceeds target power (3 kW from 3 passes) Output saturates in agreement with model Measured at RAL Measured at CERN

6. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Amplifier 2 10kW from Amp 2 corresponds to 6.7  J/pulse Beam uniformity is better than Amp 1 (fine fringes are an artefact) but rod is underfilled Overfilling improves saturation so steady state is reached but energy is reduced

7. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Pulse slicing Risetime is ~4ns Extinction ratio, throughput and level of induced noise remain to be optimised (noise level in above trace is misleading) Power handling, with additional AOM, remains to be confirmed Test of 1.54  s Pockels cell and driver confirms triggering and basic operation

8. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Frequency multiplying Crystals are available for two frequency quadrupling schemes: 2 × type I in BBO (preferred) Type II in KTP + type I in BBO (allows two IR polarisations, perhaps for 3 GHz multiplexing) Tests with Amp 1 (low energy) showed an IR-UV conversion efficiency of up to 7% Extrapolation to Amp 2 should allow system specification to be met

9. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Task listing Oscillator & preamplifier Complete – April 2005 Amplifier 1 (5 Hz) Complete – April 2006 1.54  s slicing (no AOM) Demonstrated – July 2006 Amplifier 2 (5 Hz) Demonstrated – July 2006 Phase coding Designed Frequency multiplying Demonstrated with Amp 1 – August 2006 Safety and machine protectionAfter delivery Coding finalisationAfter delivery Frequency multiplying finalisationAfter delivery Amplitude stabilisationAfter delivery Single-pulse and AOM slicingAfter delivery 50 Hz testingAfter delivery 50Hz thermal lensing correctionAfter delivery Laser system shipped from RAL to CERN at end of August 2006

10. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Lasers at CERN Oscillator in operation – September 2006 Preamplifier in operation after service by High Q Laser – November 2006 Amplifier 1 in operation – November 2006 Amplifier 2 assembled and tested (beams not optimized)– January 2007

11. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Oscillator Preamplifier Amplifier 1 Amplifier 2 Pulse slicing Pockels cell Fiber-optics coding system CERN installation

12. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Amplifiers hardware Amplifier 2 Chillers for amplifier diodes 55 l/min and 75 l/min Drivers for 5 diode laser stucks of Amplifier 2 120 A each

13. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Pulse coding EO Modulator 140.7 ns macropulses Variable delay Variable attenuator 140.7 + 0.333 ns delay 320 mW in from oscillator ~30 mW out to preamp Fibre modulation, based on telecoms technology, is fast but lossy and limited in average power Measurements on the High Q system suggest 10dB loss before the preamp results in <3dB output reduction Delay can be adjusted by varying the fibre temperature (~0.5ps/°C) Attenuation can be controlled by varying the fibre bending losses Preliminary assembly and tests of temperature tuning were carried out at RAL

14. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Pulse slicing with AOM AO Deflector Output to doubler Pockels cell Input from Amp 2 RF Driver Pockels Driver AO deflector could reduce power loading on Pockels cell by up to 80% for most of the macropulse QS41-5C-S-SS2

15. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Timing for CLEX Probe-beam

16. CTF3 Collaboration meeting – CERN, 16-17 January 2007 Thank you for your attention Acknowledgments RAL Marta Dival Graeme Hirst Kurdi Gabor Emma Springate Bill Martin Ian Musgrave CERN Guy Suberlucq Roberto Losito Nathalie Champault Arvind Kumar