, EUROnu Meeting, Strasbourg J. Pasternak Status and recent progress on muon IDS-FFAG J. Pasternak, Imperial College, London / RAL STFC Work in collaboration and with contributions from: M. Aslaninejad (IC), J. Scott Berg (BNL), D. Kelliher (ASTeC/STFC/RAL), S. Machida (ASTeC/STFC/RAL), H. Witte (JAI)

, EUROnu Meeting, Strasbourg J. Pasternak Outline of the talk Current baseline IDS FFAG design and alternative (J. Scott Berg, S. Machida). Studies of injection/extraction for IDS muon FFAG (D. Kelliher, J.P., M. Aslaninejad, H. Witte). Injection/extraction hardware design studies (M. Aslaninejad, H. Witte, J.P.). Summary and future plans.

, EUROnu Meeting, Strasbourg J. Pasternak Non-scaling FFAG is preferred for muon acceleration from 12.6 to the final 25 GeV at the Neutrino Factory. Advantages include: Allows very fast acceleration (~8-16 turns). Large dynamic aperture due to linear magnets + high degree of symmetry More turns than in RLA – more efficient use of rf Quasi-isochronous – allows fixed frequency rf Orbit excursion and hence magnet aperture smaller than in the case of a scaling FFAG Principles of NS-FFAG will be soon tested during EMMA commissioning. Introduction

, EUROnu Meeting, Strasbourg J. Pasternak Current NS-FFAG baseline Lattice choice triplet with long drift: due to longest drift injection/extraction seems to be most feasible comparing to other lattices allows for symmetric injection/extraction, good performance but less cost-effective than the short drift triplet, lattice needs to be further studied and optimised. chromaticity correction can be added in order to correct the final energy spread due to ToF Number of cells64 Circumference546 m RF voltage1.119 GV Max field in F magnet 3.6 T Max field in D magnet 6.5 T F magnet radius15.3 cm D magnet radius11.5 cm Muon decay5.6 % Injection energy12.6 GeV Extraction energy25 GeV Scott’s lattice parameters.

, EUROnu Meeting, Strasbourg J. Pasternak Alternative solution - Nonliner NS-FFAG, S. Machida Layout of FFAG with insertions

, EUROnu Meeting, Strasbourg J. Pasternak Introduction to injection/extraction Working assumptions: Try to distribute kickers to reduce their strengths. Apply mirror symmetric solution to reuse kickers for both signs of muons. FDFFFDD Septum Positive Muons Negative Muons Septum Kickers

, EUROnu Meeting, Strasbourg J. Pasternak Injection/Extraction in the Long Drift Triplet, D. Kelliher SystemInjectionExtractio n Typehorizontalvertical Number of kickers34 Magnetic field in kickers T0.078 T Kicker/septum length 2.4 m Septum field2 T~4 T Total number of cells used 56 Injection geometry Extraction geometry Large beam excursion near the septum requires special magnets with large aperture. Those magnets may introduce orbit and optics distortions (correction can be possible).

, EUROnu Meeting, Strasbourg J. Pasternak Orbit shift due to extended fringe fields, J. P. GeV m There are 3 curves on the plot: -orbit with the hard edge model, - with the soft edge model, - with shifted magnets Zoom to see the difference between hard edge and soft edge results with shifted magnets. This study suggest, that just by shifting the magnets we can correct the effect of special magnets on orbit distortion in the injection/extraction regions.

, EUROnu Meeting, Strasbourg J. Pasternak Preliminary study of IDS kickers (H.W., J.P.) PS PFN switch Transmission line Kicker Termination Due to the proton beam time structure, at least 3 independent Pulse Forming Networks (PFNs) and switches are needed for every muon train. Termination is very important to avoid reflections back to magnet (for injection). Current is most likely to high for a single thyratron, but we can connect them in paralell. Kicker field~0.1 T Kicker aperture0.3m x 0.3 m Voltage60 kV Max current~30 kA Rise/fall time1.5 us Kicker inductance~3 uH System impedance1 Ohm Number of kicker subsections12 Number of PFNs per kicker12 Total length of the kicker2.4 m

, EUROnu Meeting, Strasbourg J. Pasternak IDS Kicker Geometry –Aperture: 0.3x0.3 m 2 –Yoke: 120 mm –Length: 2.4 m Field: 100 mT Current: 29 kA Magnetic energy: 500 J Inductance (single turn): 2.8 uH Impedance matching –Add 5 plate capacitors (40 mm available) Kicker geometry EM simulations, M. Aslaninejad.

, EUROnu Meeting, Strasbourg J. Pasternak Pulses for 3 muon buch trains separated by 100 us.

, EUROnu Meeting, Strasbourg J. Pasternak Recent progress on kicker circuit, H. Witte R term L mag 1 Ohm PFN 1 PFN 2 PFN 3 PFN 4 PFN 5 PFN 6 PFN 7 PFN 8 PFN 9 3 Ohm T fire =0 us T fire =100 us T fire =200 us The assumed impedance was changed: Each PFN: Z= 3 Ohms Voltage: 60 kV Peak current: 30 kA Peak current thyratron: 10 kA Kicker: subdivided into 3 smaller kickers Each kicker: Travelling wave, 20 sections

, EUROnu Meeting, Strasbourg J. Pasternak Average current in Kicker 1.5 us 2 us

, EUROnu Meeting, Strasbourg J. Pasternak Injection/extraction schemes in the NS-FFAG lattices were evaluated. The triplet lattice with long drift was chosen as the baseline. Alternative Nonlinear NS lattice with insertions and partial chromaticity correction was proposed. More beam dynamics studies are needed (chromaticity correction, errors, insertion). Substantial progress on the injection/extraction kicker design was achieved! Work focuses on the design of the superconducting extraction septum! Summary