Linac4 ion source modelling codes: NINJA, ONIX, IBSimu Stefano

Linac4 ion source modelling codes: NINJA, ONIX, IBSimu Stefano Mattei ABP-CWG meeting 31/10/2017

Linac4 short intro Linac4 will be the new injector to the PSB, replacing Linac2 Linac2: 50 MeV proton beam Linac4: 160 MeV Hbeam Currently in commissioning stage 160 MeV already achieved The ion source is the first component of the accelerator, providing the H- ion current More details: A. Lombardi THE LINAC4 PROJECT, Proceedings of HB2016, Malmö, Sweden http://accelconf.web.cern.ch/AccelConf/hb2016/papers/moam2p20.pdf 31/10/20 S. Mattei ABP-CWG meeting 2

The Linac4 H- ion source Octupole cusp magnets -45 kV H2 gas 0V 0V RF coil Ferrites -35 kV Plasma H2 H- 45 kV 45 keV H- beam Filter magnets NINJA Modelling the RF-plasma heating 31/10/20 ONIX Detailed model of the beam formation S. Mattei ABP-CWG meeting IBSimu Extraction and beam transport 3

NINJA code Kinetic code (Particle-In-Cell) for the simulation of the RF plasma heating in inductively coupled plasmas Code developed in close collaboration with KEIO University in Japan Applied for the simulation of CERN’s Linac4 and CHARLIE test bed at University of Augsburg Simulate the RF-plasma heating Investigate the effect of design and operational parameters on the plasma characteristics Provide inputs to beam formation simulations (ONIX) 31/10/20 S. Mattei ABP-CWG meeting 4

NINJA code: physics Particle-In-Cell Monte Carlo Collisions 2.5 D in cylindrical coordinates: 2D EM field calculation (azimuthal symm.) 3D3V particle dynamics Set of over 200 cross-sections covering the most important reactions in hydrogen Implicit integration scheme Plasma species: e-, H , H2 , H3 , H neutrals H, H2(v) electron – neutral electron – ion ion – neutral Coulomb collisions Coupling with static magnetic field simulations (Opera VectorFields) imported via 3D fieldmap 31/10/20 S. Mattei ABP-CWG meeting 4

NINJA code: specs Programming language: Fortran90 libraries Fortran77, Fortran90 OS: Linux Compilers: successfully run with GNU, INTEL, NAG and PGI we typically run with INTEL Libraries: all open source - NITSOL (Fortran77) - BLAS (Fortran77) - LAPACK (Fortran77) - SPARSKIT (Fortran90) Parallelization: MPI Licensing: not open-source, discussion ongoing with collaborators at KEIO University Documentation: A fully implicit Particle-In-Cell Monte Carlo code for the simulation of inductively coupled plasmas, in preparation for submission to “Journal Computational Physics” 31/10/20 S. Mattei ABP-CWG meeting 4

NINJA: application Grid: Ng 104 Particles: Np 106-107 t 10-10 s We need to simulate 10-20 µs 105-106 time steps Computing time: 10 days on 12 cores (engpara on lxbatch) Parameter scans required: RF power Gas pressure Magnetic configuration Antenna position NINJA provides the plasma parameters (temperatures, densities and fluxes) over the volume of the plasma chamber 31/10/20 S. Mattei ABP-CWG meeting 7

ONIX ONIX is a 3D Particle-In-Cell code for the simulation of the beam formation in a negative ion sources Initially developed in the laboratory LPGP, Orsay, France in order to simulate the extraction region of an ITER-like negative ion source Applied for the simulation of the Linac4 H- ion source Study the effect of volume/surface produced H- on the extracted current and beam emittance S. Mochalskyy, J. Lettry, T. Minea, New journal of physics 2016 http://iopscience.iop.org/article/10.1088/1367-2630/18/8/085011 31/10/20 S. Mattei ABP-CWG meeting 8

ONIX: specs 3D Particle-In-Cell Monte Carlo Collision electrostatic code Owner: LPGP Orsay and IPP Garching Parallelization: MPI Performance: typical run is performed using 20 million macro particles with a meshing of 110x100 100 PIC nodes. The code performance is 0.1 μs per day on 20 cores. Normally 1-2 μs simulation time is sufficient to reach steady state. Currently work in progress to reduce the cell size and improve parallelization to run on large clusters ( 1000 cores) Licensing: not open-source Currently maintained by LPGP and IPP Garching 31/10/20 S. Mattei ABP-CWG meeting 9

ONIX: future OFF-line coupling between NINJA and ONIX Extract from NINJA the plasma parameters (ne, Te, flux of H0, etc) at the entrance of the collar region ONIX: defines the resulting beam characteristics Goal is the optimization of the plasma electrode geometry and puller optics Work to be done in collaboration between CERN-KEIO-LPGP-IPP provided resource availability fluxes Finer resolution 31/10/20 S. Mattei ABP-CWG meeting 10

IBSimu An ion optical computer simulation package for ion optics, plasma extraction and space charge dominated ion beam transport using Vlasov iteration. Used at CERN for 5-6 years: Linac3, Linac4, ISOLDE http://ibsimu.sourceforge.net/ Developed by T. Kalvas @ U. of Jyväskylä (Finland) Solid geometry definition using 2D DXF files, 3D STL files, mathematical formulation, etc. Finite Difference Method solver for 1D, 2D and 3D Poisson equations with edge smoothing. Particle trajectory iteration in self-consistently calculated electric and imported magnetic fields. Space charge density calculation from trajectories. Vlasov iteration for self-consistent simulation of high space-charge beams. 31/10/20 Nonlinear plasma models for positiveABP-CWG and negative S. Mattei meetingion extraction. 11

IBSimu: specs Programming language: C OS: Linux, Windows Compilers: GNU Libraries: several for background functionality (graphics, math, etc.) listed on the website Parallelization: none Licensing: open-source, GNU General Public License Maintained by T. Kalvas Documentation: http://ibsimu.sourceforge.net/index.html 31/10/20 S. Mattei ABP-CWG meeting 12

IBSimu: application Beam transport given geometry and potentials e- and H- beam including space-charge, trajectories Computing time: 1-2 days Parameter variations: Extracted currents, e- / H-, geometry, potentials. Typically 200-300 runs Limitation of IBSimu is the plasma model not suited for surface produced negative ions Linac4 H- ion source extraction optics: Daniel Fink: http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4916433 Oystein Midttun: http://scitation.aip.org/content/aip/journal/rsi/85/2/10.1063/1.4824814 31/10/20 S. Mattei ABP-CWG meeting 13

IBSimu: future NINJA-ONIX can provide the beam phase-space few mm from the plasma electrode IBSimu can track it through the e- beam dump section and provide input to TRAVEL and PATH NINJA ONIX IBSimu TRAVEL/PATH Goal is the optimization of the overall ion source emittance 31/10/20 S. Mattei ABP-CWG meeting 14