The way to fastand "loss-free" SPS kickersE. Gaxiola

With contributions from AB-BT-KSL sectionand F. Caspers, T. Kroyer, M. Timmins, J. Uythoven

KickerFunctional specification:Fast rise- and fall-time very stable magnetic field pulseRise-, fall-times:200 ns to 1.1 sFlattop ripple:0.5 to 1%Induction field0.08 to 0.16 TPS / SPS days 13/01/2005

Limitations:Ferrite Curie temperature:Beam induced lossesBeam impedance:Beam stabilityMaximum operating voltageSwitchesMaximum currentFerrite core saturation Bsat

Pulsed powerLow impedance travelling wave magnet

Speciality magnets* Vacuum; * High voltage; * High currents

Todays kicker systemsUpgraded thyratron switch performanceSemiconductor components applicationsHeat conductance coolingReduced beam impedance(longitudinal + transverse)Beam stability?!

Injection MKP2001 4 batch LHC-type injectionModernisation/upgrade MKP systems #1 to #3Impedance increase 12.5 16.7 Faster rise timeImproved flattop ripplePFNs upgrade:Pulse fine tuning

2004Rise time improvements for MKP system #42006Final fine tuning (as was done for MKE)

Extraction MKE LSS42003Magnet cooling for reduced beam induced heatingPower semiconductor diode stacks Increased reliability + lifetime(more cost efficient solution)from LHC MKD kicker generator development2004Shortened MKE Generator PFN lengthsOptimized rise timePFN front cell adjustments+ adjustable PFN first coilReduced kicker rippleMagnet damping resistorsOptimized 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 reachedOct 2003Step 1:As installed in 2003July 2004Step 3:Mismatched TMR valuesNov 2004Step 4:Fine-tuning adjustable PFN firstcoil for each MKE generatorApril 2004Step 2:Adding Magnet Damping Resistors+ PFN front cell adjustments

Chart1

2.53.88.592220

1.33.890310

1.11.19.8454

1.11.110.5232

Rise time

Fall time

Usable batch time

Overshoot [%]

Kick pulse flattop ripple [%]

Post kick pulse ripple [%]

Subsequent improvement step

Time [us]or%

Pulse parameter

SPS MKE LSS4 pulse parameters

Sheet1

Oct-03Apr-04Jul-04Nov-04

Risetime [us]2.51.31.11.1

Falltime [us]3.83.81.11.1

Usable batch length [us]8.599.810.5

Overshoot [%]9042

Flattop ripple [%]22353

Post kick pulse ripple [%]201042

Sheet2

Sheet3

Tune kicker MKQHBeam impedance reductionTest bench

MKQH kicker magnet withceramic inserts withresistive layer coating

Proof of principle2004 positive results for beam impedance

Approach INot applicable to MKE:Due to significantly increased rise time!

Results MKQH kicker magnet< 20042004T*Curie reached at TMKE,reference=45C>90CRise time 1-99%:0.6 s2.9 s

Results Impedance Measurements MKQH

Further improvementsStudies underwayCapacitive coupling by using metallic finger type strips: Beam impedance reduction Im{Z} and Re{Z} Reduced heating via Re{Z}2006Machine 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

Horizontally: 8.2 sigma SPS beamVertically: 3.2 sigma SPS beam

High voltage conductor

Alumina plates with metallic finger strips

Ferrite

Ground electrode

Approach IIIStrips Printed Directly on FerritesInterdigital comb structure 20mm spacing surface discharge

Results Impedance MeasurementsSingle Kicker Cell (Approaches II and III)

MKE / MKQH kickers2004Lab:Significantly reduced beam impedance!Reduced lossesNext step(s):2005Study vacuum high voltage breakdown discharge characteristicsTravelling wave kicker:To be X-checked2006SPS tests in LSS6

SummaryVery useful knowledge build-up phase98 2006New kicker diagnostics were added over the past years.Tests for SPS ComplexApplication 2003 2008Confirmation of the positive impact of the upgrade of the injectors for LHCOld recuperated equipmentUpgraded 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 doneFurther simulations + tuning to be doneHigher reproducibility neededSpare to be finalized with increased diagnosticsMKQH:Useful test-bed with proof of principle,not straight forward applicable to other kickersBeam impedance reduction realizedMKE:Further tests to be done with stripes for voltage holding, vacuum, pulse shape in 2006 beam testsLarger 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 limittogether with damper practically fulfilling CNGS double batch specs(is damper use the definitive solution?)