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CLIC Workshop 2014: Low Emittance Rings experimental program

CLIC Workshop 2014: Low Emittance Rings experimental program. CLIC DR STRIPLINE KICKER DESIGN AND DEVELOPMENT. C. Belver -Aguilar (IFIC) On behalf of: A. Faus-Golfe (IFIC), F. Toral, M.J . Barnes (CERN ) . http://gap.ific.uv.es. KICKER TECHNOLOGY AND PARAMETER CHOICES.

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CLIC Workshop 2014: Low Emittance Rings experimental program

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  1. CLIC Workshop 2014: Low Emittance Rings experimental program CLIC DR STRIPLINE KICKER DESIGN AND DEVELOPMENT C. Belver-Aguilar (IFIC) Onbehalf of: A. Faus-Golfe (IFIC), F. Toral, M.J. Barnes (CERN) http://gap.ific.uv.es

  2. KICKER TECHNOLOGY AND PARAMETER CHOICES PARAMETERS FOR THE STRIPLINES OF THE EXTRACTION KICKER OF THE DAMPING RINGS FEEDTHROUGH TO LOAD FEEDTHROUGH TO LOAD MAGNETIC FIELD ELECTRIC FIELD FEEDTHROUGH TO PULSER (negative voltage input) FEEDTHROUGH TO PULSER (positive voltage input) BEAM 6 February 2014 CLIC Workshop 2014: LowEmittanceRings1/12

  3. STRIPLINE KICKER OPERATION COUPLED LINES → TWO OPERATION MODES: ODD AND EVEN MODE • ODD MODE: • The electric field lines have an odd symmetry about the centre line, and a voltage null exists between the two electrodes. • There is a virtual ground plane midway between the electrodes (capacitance = 2C12) • The effective capacitance between an electrode and ground is . • EVEN MODE: • The two electrodes are at the same potential, so there is no charge stored in the capacitance between them. • The resulting capacitance of either electrode to ground is . Eachmode has itsownelectromagneticfieldpattern and itsowncharacteristicimpedance: 6 February 2014 CLIC Workshop 2014: LowEmittanceRings2/12

  4. HFSS SIMULATIONS • It is confirmed that a small stripline beam pipe radius results in closer values of even and odd mode characteristic impedance. • The even mode characteristic impedance of striplines is always higher than the odd mode. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings3/12

  5. STRIPLINES GEOMETRY CHOICE 6 February 2014 CLIC Workshop 2014: LowEmittanceRings4/12

  6. COMPONENTS CHOICE: ELECTRODE SUPPORTS • In order to ensurethealignment of theelectrodesalongtheirentirelength (1.639 m), they are fixedoutsidetheaperturebyusingfourequally-spaced Macor rings, of 10 mm lengtheach. • Once theelectrodes are aligned and fixed to the Macor rings, thisassemblyis placed insidethestainlesssteeltube, and its angular position isguaranteedby a pin embedded in thestriplinesbeam pipe wall. • Thenumber of Macor rings and theirlengthwereselectedbystudyingthemechanicalrequirements and theimpedancemismatchintroducedbytherings. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings5/12

  7. BEAM COUPLING IMPEDANCE: LOW FREQUENCY STUDY • Geometric parameters: • = 1,8 rad • = 1,7 m • = 20 mm • At low frequencies: • Longitudinal impedance per harmonic: • Transverse impedance: 6 February 2014 CLIC Workshop 2014: LowEmittanceRings6/12

  8. MATERIAL AND COMPONENTS CHOICES • The beam pipe housing the stripline electrodes is a stainless steel tube of 1.712 m length. The internal diameter of the tube is 40,5 ± 0,2 mm. • Aluminium has been chosen for the electrodes, because it is relatively easy to achieve the tight tolerances required during manufacturing. • The electrode supports will be manufactured using Macor, which is a machinable glass ceramic. • All the materials and components chosen, such as feedthroughs, are compatible with ultra-high vacuum, of the order of 10-10 mbar. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings7/12

  9. FIRST TESTS AT CERN S11 PARAMETER • The frequencybetweenpeaksis≈90 MHz, whichcorresponds to thetwo-waydelay of theelectrodes. • Theelectrodesupports (Macor rings) increasethemagnitude of thereflectionparameterstartingfrom 300 MHz, of everythirdpeak. • Theseparationbetweenthesemaximacorresponds to thedistance, there and back, betweentheequally-spaced Macor rings. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings8/12

  10. ONGOING STUDIES: ELECTRODE HEATING • There are twoways of heatingtheelectrodes: • Withthedriving pulse: itis a priorynot a problem • Withthebeam • Strategy: • Simulations of wakeimpedancewithbeam: getloss factor; • Eigenmodesimulationtogetthefielddistributionof losses; • Input power and fielddistribution and gettemperaturedistribution. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings9/12

  11. ONGOING STUDIES: ELECTRODE HEATING • Powerdeposition in theelectrodesforthe ALBA beam (T. Guenzel) < 1 W U. Wienands, et al. (SLAC), High-TemperatureKickerElectrodesfor High-Beam-CurrentOperation of PEP II. EPAC 2004. (aluminiumnotpolished) (stainlesssteel) • Forthe longitudinal expansion of thestriplinesdue to heating, thistemperatureisnotexpected to be a problem. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings10/12

  12. FUTURE TESTS WITHOUT BEAM • Verification of thestriplinedimensions. • Vacuumcompatibility. • High voltage performance. • Longitudinal and transversebeamcouplingimpedancemeasurements.. FUTURE BEAM TESTS • Striplinesnotused as a extraction device andwithoutinductive adder • Longitudinal and transverse beam coupling impedance • Striplines not used as extraction device and withinductive adder • Field inhomogeneity • Pulse shape and repeatability • Long term reliability of the system • Once long-term reliability is demonstrated: possible use as extraction device 6 February 2014 CLIC Workshop 2014: LowEmittanceRings11/12

  13. SUMMARY • The stripline design provides the performancespecified for the extraction kicker of the CLIC DRs: excellent field homogeneity, good power transmission and reasonable broadband beam coupling impedance. • The stripline design has been carried out by using analytical approximations and simulations to optimize the stripline geometry. • Beam coupling impedance has been studied both analitically and with CST simulations, only for a low frequencies. The behavior of the kicker at high frequencies is an open question to be studied. • A prototype of the extraction stripline kicker for the CLIC DR has been manufactured by Trinos Vacuum Projects (Valencia, Spain). • Losses due to the circulating beam are presently being studied. • Laboratory tests have commenced at CERN labs. Results for the reflection parameter S11 match quite well with the results predicted by the simulations. Other laboratory tests will be done in the next months. • The stripline and the inductive adder will be finally tested separately and jointly with beam. 6 February 2014 CLIC Workshop 2014: LowEmittanceRings12/12

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