Field Scaling Electrons

These are a special type of electron used in testing. Most notably, they consist of only one physical particle per macroparticle. They are in fact given a variable weight, which is used to track whether the particles have been created via secondary emission. Each particle also has a scaling value, allowing for multiple voltage levels to exist in the simulation simultaneously. Since there is only one physical particle per macroparticle, these particles will have negligible effect on the simulation.

The primary use of these particles is to scan a structure for multipacting resonances across a number of power levels at the same time.

To add Field Scaling Electrons, right click on the “KineticParticles” element, hover over the “Add TestParticleSpecies” and choose “Field Scaling Electrons”.

Field Scaling Electron Loader

This particle loader is very similar to a standard particle species loader, with some notable exceptions.

description: A space to provide a descriptive comment for the particle species.

load density: Only the relative density of particles may be specified, as this is the same as the physical density.

physical density: This will specify the number of particles per cell.

particle load placement: At this time particles may only be loaded according to a bit-reversed algorithm.

load duration: Whether to only load the particles at the beginning of the simulation or repeatedly.

• initialize only: Particles will only be loaded at the beginning of the simulation.

• repeat loading: Particles will be loaded according to the parameters below.

  start time: The time at which to start loading particles.

  stop time: The time at which to stop loading particles.

  load after initialization: Loading will repeat in all cells during the loading period.

  load upon shift: Load particles into cells brought into the simulation by a moving window.

scaling factor: This will determine the minimum value, maximum value, and scaling factor applied to the field scaling electrons. So for example with a minimum value of 10, and a scaling factor of 3, that individual electron is charged to 30V.

minimum scaling factor: The minimum voltage of the particles loaded.

maximum scaling factor: The maximum voltage of the particles loaded.

number of scale factors: The number of scale factors, or steps, between the minimum scaling factor and maximum scaling factor.

volume: The volume in which to load particles.

• cartesian 3d slab

• cylindrical 2d slab

Additional Features:

Fewer additional features are available for Field Scaling Electrons. The only emitter available for Field Scaling Electrons is a secondary emitter.

• Secondary Electron Emitter

And the only available particle boundary conditions are: Absorbing, Boundary Absorb and Save, Cut-Cell Absorb and Save, Interior Absorb and Save, and Reflecting.

• Properties of Particle Boundary Conditions