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SIMION 8 Ion and Electron Optics Program

The Industry Standard for Ion Optics Simulation

Overview: SIMION Version 8 is a software package primarily used to calculate electric fields and the trajectories of charged particles in those fields when given a configuration of electrodes with voltages and particle initial conditions, including optional RF (quasistatic), magnetic field, and collisional effects. In this, SIMION 8 provides extensive supporting functionality in geometry definition, user programming, data recording, and visualization. It is an affordable but versatile platform, widely used for over 25 years to simulate lens, mass spec, and other types of particle optics systems.

Applications: SIMION 8 is suitable for a wide variety of systems involving 2D or 3D, static low-frequency (MHz) RF fields: from ion flight through simple electrostatic and magnetic lenses to particle guns to highly complex instruments, including time-of-flight, ion traps, quadrupoles, ICR cells, and other MS, ion source and detector optics.

Audience: No program can be all things to all people. SIMION 8 is aimed at a wide audience, with extensive use in both academia and industry, including most of the major mass spec companies. SIMION 8 is positioned as an affordable package that nevertheless provides solid implementations of many core capabilities (listed below), and a choice among multiple approaches (as when defining geometries). The program uses direct methods such as finite-difference that are straightforward to apply but are also optimized and extended, making SIMION 8 suitable for a wide variety of real-world systems. The methods are interactive to promote understanding, allowing you to adjust parameters during the simulation and immediately visualize the resultant fields and trajectories. The software is programmable, allowing users to extend and automate the capabilities in novel ways. It is also substantially documented. It runs on Windows and Linux.

What SIMION 8 is not: SIMION 8’s scope does not, at least currently in itself, include certain magnetics (e.g. permeability), dielectrics, space-charge, and high-frequency (HF) radiation problems. For example, space-charge limited cathode emissions, dielectrics, secondary emissions on curved surfaces, and certain fine geometries in BEM are really the realm of CPO. Some FEM packages go more into magnetics and beyond the scope of the particle optics focus of SIMION 8. There is, however, the possibility to use SIMION 8 with these other programs.

Figure: Screenshots left show model, field, and trajectory views of an RF quadrupole example in SIMION 8.

Figure: Screenshots left show model, field, and trajectory views of an RF quadrupole example in SIMION 8.

View additional screenshots on the website

Capabilities and Features:

Electrostatic field solving in 2D and 3D, up to almost 200 million points (2GB) (extended and faster in version 8), with optimizations for symmetry and mirroring. Uses finite difference with much optimized linear-time solving. Small arrays solve in under a minute; large arrays may take roughly an hour (varies on conditions). A workbench strategy allows you to position, size, and orient up to 200 instances (3D images) of potential arrays of different grid densities and symmetries to permit the simulation of much larger systems that don’t easily fit into a single array.

Magnetic field support: Though SIMION 8 is not a full magnetic field solving program (e.g. permeability is not handled), it will solve a restricted case involving scalar magnetic potential (identical to the electrostatic case) and Biot-Savart wire/solenoid calculations (enhanced in 8.0.3). Also, an arbitrary (vector) magnetic field can be imported from an external program or defined analytically, optionally superimposed on an electrostatic field (e.g. penning trap or ICR cell), for the purpose of particle flying.

Low frequency time-dependent or RF support: Electrode voltages may be adjusted in a general way during particle flight via user programming–e.g. to step or oscillate electrode voltages in some manner. MHz range quad and ion trap simulation are often performed. (Much higher frequencies or radiation effects are not simulated since SIMION 8 applies the quasistatic approximation.)

Particle tracing: Particle trajectories are calculated given previously calculated or defined fields. Includes relativistic corrections, Runge-Kutta with variable-length dynamically adjusting and controllable time-steps, and user programming capabilities for novel effects (such as ion-gas scattering). Particle mass and charges can be defined individually or according to some pattern or distribution (enhanced FLY2 format is new in version 8). Particle tracing is fast–millions of particles can be handled.

Geometry definition via multiple methods: a 3D paint-like program (Modify), CAD import from STL format (new in version 8 or SL), solid geometry defined mathematically via a text file (GEM file), and programmatic manipulation of arrays from such languages as Perl, Python, and C++ (SL Libraries) (new in version 8 or SL). An application called Virtual Device, available separately, provides a GUI for creating GEM files too.

Contour and potential energy surface plots (optionally with ion trajectories superimposed) are displayed interatively and are a core feature of viewing.

Viewing of the system is highly interactive, allowing adjustment of parameters and viewing of the system even during ion flight. Supports cutting away volumes to see trajectories inside; zooming; viewing potential energy surfaces, contour lines, and trajectories; and reflying particles as dots for movie effects. Nice OpenGL viewing (new in version 8 or SL) of potential arrays also available.

Data recording of parameters at various stages in particle flight, to screen or delimited text file, for subsequent analysis of fields and trajectories. Analysis can be done via SIMION 8 user programming, in a program or language of your choice (e.g. Excel), or in the Virtual Device program, available separately, which has analysis and plotting capabilities for SIMION 8 (e.g. phase plotting and histograms from trajectory data).

User programming: During ion flight, you may control electrode voltages, define or modify fields, scatter or deflect ions (e.g. ion-gas collision models), tune (optimize) lens voltages, compute results, export data to programs like Excel via a COM interface, and do many other things. The Lua language (new in version 8) is now directly embedded in SIMION. Programming may also be used to operate SIMION in batch mode (new in version 8), such as for geometry optimization, or read/manipulate potential array files (new in SL or 8).

Basic charge repulsion effects to estimate the onset of space-charge. (Note: for more advanced and numerically accurate space-charge and space-charge limited cathode emission calculations, we suggest considering the CPO software.)

Documentation and examples: SIMION comes with an extensive 450-page printed manual, additional electronic documentation, example files, and ASMS course notes. There are also the online SIMION Info pages for the latest SIMION tips, articles, and resources. You can find hundreds of academic papers that utilize SIMION.

Package contains a 450-page printed manual, installation CD with software license key number (for receiving software updates), and quick start notes. The installation CD installs the software, examples, and additional documentation.

Upgrades: Free upgrades to 8.0.x versions and versions released within a year of 8.0.0 (at least) are provided as downloads from

Support: Limited free support via email and phone is included, and there is a message board. See also documentation above.

Supported systems: Tested on Windows Vista, XP, 2003, 2000, and NT, as well as Wine/Linux. See also System Requirements.

Users of previous versions of SIMION, please see Changes in SIMION 8.


Extending SIMION Software:

SIMION software provides a lot of capabilities. However, additional capabilities may be found in these separate packages:

  • Virtual Device – developed independently by a SIMION user, this program provides a GUI for building GEM files, plotting/data analysis for recorded SIMION data, and ION file creation.
  • CPO – If SIMION is not enough for you, we also provide this alternative high-end package, which provides high accuracy and space-charge, space-charge limited cathode emission, and dielectrics calculations via its distinctive advanced boundary element method (BEM) of calculation–in which the electrode surfaces are defined by a non-rectangular surface mesh and the charges on the surface, and optionally in space, are calculated as an intermediate step. Additional built-in features, and approx. 100 examples included.

For more information, see the examples and online documentation.

SIMION software has a long history with the first PC versions starting in the early 1980’s and developed for the next two decades up to Version 7 under David Dahl at Idaho National Laboratory (US Department of Energy) and Version 8 continued at SIS.

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