generalQuadSim

Simulates ion trajectories in an RF only quadrupole device with arbitrary electrode geometry considering space charge and interaction with a flowing background gas. The electrode geometry and resulting electric field is defined by a set of SIMION potential arrays. The pressure / density and flow velocity of the background gas can be defined by spatially resolved fields, e.g. from an CFD simulation of the simulated device.

Warning

This application has to be revised. It can fail with an exception under certain conditions.

Note

Currently, no collisions of simulated particles with electrode surfaces are considered in this application and the RF frequency of the device is currently fixed at 1 MHz.

Simulation configuration description

sim_time_stepsinteger

Number of simulation time steps

trajectory_write_intervalinteger

Interval, in time steps, between writes to the trajectory result file.

dtfloat

Time step length in seconds.

n_ionsvector of integers

Number of ions with the masses defined in ion_masses

ion_massesvector of float

Vector of ion masses in amu.

V_rffloat

RF amplitude in V.

V_entrancefloat

DC amplitude for the entrance electrode into the quadrupole in V.

P_factorfloat

Scaling factor for the pressure field.

space_charge_factorfloat

Multiplication factor for particle-particle interaction (space charge)

collision_gas_mass_amufloat

Molecular mass of the particles of the background gas in amu.

collision_gas_diameter_angstromfloat

Effective collision diameter of the particles of the background gas in angström.

background_temperature :

Isotropic temperature of the background gas in K.

start_q_length_mmfloat

Length of the ion start zone in axial direction in mm.

entrance_aperture_mmfloat

With of the quadratic cross section of the ion start zone in mm.

q_start_mmfloat

Begin of the ion start zone in axial (x) direction in mm.

restart_q_length_mmfloat

Length of the ion start zone for restarted ions in axial (x) direction in mm.

max_q_length_mmfloat

End position in axial (x) direction, where ions are terminated in mm.

max_r_mmfloat

Maximal distance in radial direction from the center line of the quad where ions are terminated.

Paths to gas parameter fields and potential arrays

Note

All file paths are relative to the simulation configuration file.

rho_field_fileFile path

Path to background gas density (rho) field.

flow_field_fileFile path

Path to background gas flow velocity field.

The potential arrays have to have the same geometric extend and are assumed to be normalized. The total potential at a location is calculated by a linear combination of the potentials:

\[U = U_{\text{RF norm.}} \cdot V_{\text{RF}} + U_{\text{entrance norm.}} \cdot V_{\text{entrance}}\]

electric_field_rf_fileFile path

Path to potential array for RF electrodes with normalized bipolar field for RF electrodes.

electric_field_entrance_fileFile path

Path to the normalized potential array for the entrance electrode.