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

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 field0.08 to 0.16 T PS / SPS days – 13/01/2005 Limitations: Ferrite Curie temperature:Beam induced losses Beam impedance:Beam stability Maximum operating voltageSwitches Maximum currentFerrite core saturation B sat  Pulsed powerLow impedance travelling wave magnet  Speciality magnets* Vacuum; * High voltage; * High currents

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

Injection MKP 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 # Final fine tuning (as was done for MKE)

Extraction MKE LSS 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 timePFN front cell adjustments + adjustable PFN first coil Reduced kicker rippleMagnet damping resistors Optimized fall timeMis-matched TMR values + Use of SPS transverse feedback system (tested in SPS MD)  CNGS double batch extraction practically within specs

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

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

Approach I Not applicable to MKE:Due to significantly increased rise time! Alumina profile with Resistive coating

Results MKQH kicker magnet < T * Curie reached at T MKE,reference =45ºC>90ºC Rise time 1-99%:0.6 µs2.9 µs

Results Impedance Measurements MKQH

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)

Approach II Bypass- insert: Double sided comb structure

Approach III Strips Printed Directly on Ferrites Interdigital comb structure 20mm spacing surface discharge

Results Impedance Measurements Single Kicker Cell (Approaches II and III)

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

Summary Very useful knowledge build-up phase’98 – 2006 New kicker diagnostics were added over the past years. Tests for SPS ComplexApplication 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 ….

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 … ? 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?)