External Circuits

External circuit models are available to assign to dirichlet boundary conditions in electrostatic simulations in VSim.

At this time the only available model is a resistive voltage model, with a resistance applied on a user supplied time constant. External circuits are only used in simulations with particles, as the current from the particles impacting the boundary condition is used to impact the applied voltage. To create an external circuit, right click on “External Circuits” and click on “Add Resistive Voltage Source”. This will create a new option called “externalVoltageN”, where N is an integer. Clicking on the new options reveals the following parameters which must be assigned. “Boundary Condition” refers to the particle boundary condition which must be set up to fully specify the external circuit in order to determine the currrent. An example which illustrates the use of the external circuit model is “cylMagnetronSputtering.sdf” found in the VSimPD examples. Once the external circuit is setup, it is available to use as a Dirichlet Boundary condition under the “FieldBoundaryConditions” option, which is found by expanding the “Field Dynamics” option.


The voltage applied before the resistor.


The resistance in between the voltage and the boundary condition.

-time constant

The time constant used to apply the impact of particle charge over.

-Boundary Condition

Particle “absAndSave” type boundary conditions need to be assigned to the external circuit model to be included in it. This is done by right clicking on “externalVoltageN” and assigning the relevent Particle Boundary Conditions.