Enhancing SPS Kicker System Efficiency: Latest Development and Future Innovations

1. The way to fastand "loss-free" SPS kickers E. Gaxiola With contributions from AB-BT-KSL section and F. Caspers, T. Kroyer, M. Timmins, J. Uythoven

2. PS / SPS days – 13/01/2005 Kicker • Functional specification: Fast rise- and fall-time very stable magnetic field pulse • Rise-, fall-times: 200 ns to 1.1 μs • Flattop ripple: 0.5 to 1% • Induction field 0.08 to 0.16 T • Pulsed power Low impedance travelling wave magnet • Speciality magnets * Vacuum; * High voltage; * High currents • Limitations: • Ferrite Curie temperature: Beam induced losses • Beam impedance: Beam stability • Maximum operating voltage Switches • Maximum current Ferrite core saturation Bsat

3. Today’s kicker systems • Upgraded thyratron switch performance • Semiconductor components applications • Heat conductance cooling • Reduced beam impedance (longitudinal + transverse) Beam stability?!

4. Injection MKP • 2001 4 batch LHC-type injection • Modernisation/upgrade MKP systems #1 to #3 Impedance increase 12.5 Ω 16.7 Ω Faster rise time Improved flattop ripple • PFN’s upgrade: Pulse fine tuning • 2004 • Rise time improvements for MKP system #4 • 2006 • Final fine tuning (as was done for MKE)

5. Extraction MKE LSS4 • 2003 • Magnet cooling for reduced beam induced heating • Power semiconductor diode stacks  Increased reliability + lifetime (more cost efficient solution) from LHC MKD kicker generator development • 2004 • Shortened MKE Generator PFN lengths • Optimized rise time PFN front cell adjustments • + adjustable PFN first coil • Reduced kicker ripple Magnet damping resistors • Optimized fall time Mis-matched TMR values • + Use of SPS transverse feedback system (tested in SPS MD) •  CNGS double batch extraction practically within specs

6. The hardware limits of the present MKE kicker system are practically reached • Oct 2003 Step 1: As installed in 2003 • April 2004 Step 2: • Adding Magnet Damping Resistors • + PFN front cell adjustments • July 2004 Step 3: • Mismatched TMR values • Nov 2004 Step 4: • Fine-tuning adjustable PFN first • coil for each MKE generator

7. Tune kicker MKQH • Beam impedance reduction • Test bench MKQH kicker magnet with ceramic inserts with resistive layer coating • Proof of principle 2004  positive results for beam impedance

8. Alumina profilewith Resistive coating Approach I Not applicable to MKE: Due to significantly increased rise time!

9. Results MKQH kicker magnet < 2004 2004 • T*Curie reached at TMKE,reference= 45ºC >90ºC • Rise time 1-99%: 0.6 µs 2.9 µs

10. Results Impedance Measurements MKQH

11. Further improvements • Studies underway Capacitive coupling by using metallic finger type strips:  Beam impedance reduction Im{Z} and Re{Z}  Reduced heating via Re{Z} • 2006 • Machine implementation on one MKE magnet (2 cells out of 7 cells) If successful:  Possible full 9 MKE fast extraction kicker upgrade LSS4 and LSS6 for 2007 and beyond (in e.g. shutdowns)

12. Bypass-insert: Double sided comb structure Approach II

13. Approach IIIStrips Printed Directly on Ferrites Interdigital comb structure 20mm spacing surface discharge

14. Results Impedance MeasurementsSingle Kicker Cell (Approaches II and III)

15. MKE / MKQH kickers • 2004 • Lab: Significantly reduced beam impedance! • Reduced losses • Next step(s): • 2005 • Study vacuum high voltage breakdown discharge characteristics • Travelling wave kicker: To be X-checked • 2006 • SPS tests in LSS6

16. Summary • Very useful knowledge build-up phase ’98 – 2006 • New kicker diagnostics were added over the past years. • Tests for SPS Complex Application 2003 – 2008 • Confirmation of the positive impact of the upgrade of the injectors for LHC • “Old” recuperated equipment  Upgraded “modern” performance. • This is only a preliminary summary of the findings. More extended analysis + documentation required. More detailed modelling  Compare measurements and simulations. Proven solutions  recommendations. CERN at the frontier: bigger and ….

17. Summary (continued) • MKP: Rise time improvements done • Further simulations + tuning to be done • Higher reproducibility needed • Spare to be finalized with increased diagnostics • MKQH: Useful test-bed with proof of principle, • not straight forward applicable to other kickers • Beam impedance reduction realized • MKE: Further tests to be done with stripes for voltage holding, vacuum, pulse shape in 2006 beam tests • Larger scale applications in 2007 …. 2008 ? • If not successful  New concept (Alternative new kickers, lots of $ + my) • MKE pulse specs: After lots of modifications (not possible for 2003 tests) now practically at their limit • together with damper practically fulfilling CNGS double batch specs • (is damper use the definitive solution?)