Simulation of Multiturn Injection into SIS-18 Seminar Beam Physics for FAIR 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Outline Motivation Linear multiturn-injection scheme Old and new PATRIC First result Advanced injection schemes Summary Outlook 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Motivation Increase of beam intensity for FAIR Increase of number of particles per beamlett As many injections as possible Low loss budget for U28+ due to dynamic vacuum  Impact of space charge within and between beamletts needs to be studied  Optimization of injection parameters for high intensity  Investigation of other injection schemes 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Single turn injection Trajectory merged into closed orbit by means of a local orbit bump 4 degrees of freedom: x, x’ at end of bump  close orbit xinj, x’inj  match bump to incoming beamlett Generated by 4 kickers Kickers switched off within one turn trajectory from transfer channel (TK) collimator beamlett local orbit bump dsep septum injection kicker nominal orbit without bump 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Multiturn injection (MTI) Singleturn injection  beam intensity limited to intensity in injector Increase of intensity in synchrotron by accumulation of beamletts  multiturn injection Problem: Fundamental theorem of beam injection Equal beamletts cannot be injected into the same phase-space volume. 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik MTI using stacking Solution: Stacking or phase-space painting Filling of different phase-space volumes Consequences: Off-centered beamletts  Deflection by quadrupoles Emittance growth: εMTI > Ninj εbeamlett SIS-18: Horizontal stacking  time-dependent horizontal orbit bump Parameters optimized empirically y acceptance x ε of full beam Idealized transverse stacking 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Simple linear Ramp Simplest approach Reduction of bump height by two beam radii 2a + thicksep per revolution Drawback: inefficient use of acceptance x’ x 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Improved linear ramp Use of quadrupolar deflection For fractional tune Qf = 0.33 beamlett returns to septum after 3 turns Sufficient reduction of bump height: 2a within 3 turns  Ramp rate determined by a and Qf septum x’ turn 2 shifted orbit x turn 1 injection x x’ x x’ x x’ x x’ shifted orbit 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Beginning of Injection Bump must be smaller than displacement of first beamlett otherwise: Minimal offset depends on ε, beta function β, Q Estimated limit: 1.5a  Beginning roughly determined by a x x’ x x’ x’ x x’ x 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Ending of Injection Last injection: bump height = 2a 3 Turns later: bump height = 0 (for Qf = 0.33)  Ending determined by a 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik PATRIC Developed at GSI Particle in cell tracking Space charge and other collective effects Lattice: Constant focusing or input from MADX Only stationary beams  Not suitable for injection PATRIC beam initialization sector map Ki, Rij, Tijk lattice parameters α, β, μ, Δμ(Δp),… particle motion 1. order lattice space charge MADX beam optics file emittance, losses, offset,… 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Extension of PATRIC Turn by turn generation and addition of beamletts Time dependent local orbit bump for injection Parameterization Modification of sector map from MADX Accounting of chromaticity PATRIC beamlett initialization addition to beam bump adjustment particle motion 1. order lattice space charge chromaticity sector map Ki, Rij, Tijk lattice parameters α, β, μ, Δμ(Δp),… MADX beam optics file without bump emittance, losses, offset,… 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik First Results 13. Mai 2019 Stefan Paret - Beschleunigerphysik

More advanced injection schemes I Skew quadrupole Emittance transfer to vertical plane by linear coupling horizontal phase space freed (formerly) used at CERN and RHIC Studied for SIS-18 (G. Franchetti, W. Daqa) but not finished β-mismatch smaller βTK  smaller a at injection  more injections possible consequence: mismatched beam proposed by C. Carli y x y d1 d2<d1 x d2 13. Mai 2019 Stefan Paret - Beschleunigerphysik

More advanced injection schemes II Emittance transfer before injection decrease of εhor at cost of εver UNILAC  smaller a  more injections possible proposed by L. Groening x x’ y y x x’ x x εver * 4 εhor / 4 Possible with space charge? Non-linear ramps PhD work of Y. El-Hayek (GSI) 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Summary Model of injection with time-linear local orbit bump Implementation in PATRIC Demonstration of first results Possible improvements of injection scheme Linear coupling β-mismatch Emittance transfer Non-linear ramps 13. Mai 2019 Stefan Paret - Beschleunigerphysik

Stefan Paret - Beschleunigerphysik Outlook Introduction of chromaticity Verification of new code Investigate impact of space charge Inclusion of field errors in MADX Consider simulations in 2.5D Simulate more advanced injection schemes Measurements in SIS-18 13. Mai 2019 Stefan Paret - Beschleunigerphysik