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Electromagentic field from charged particle

Posted Sep 6, 2017, 3:19 a.m. EDT Low-Frequency Electromagnetics, RF & Microwave Engineering Version 4.3 1 Reply

David Rohrbach
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Hello everyone,

at the moment I have a 2D model with different layers (each with different electromagnetic properties (permeability, conductivity, permittivity)) which build an upper and a lower layer-system with a vacuum cap in between. Now I would like to add a charged particle (or better: a electron beam with Gaussian shape) flying with a velocity of almost c through this vacuum cap. For the moment I do not want to consider any back-reaction from the produced fields to the particle - I am only interested in the produced em-field (i.e. the wakefield) in the layers due to the charged particle. Does anybody know how I can add such a moving, charged particle? At the moment I use the electromagnetic wave, Frequency Domain for my model. For licence issue I should use the AC/DC or the RF module (I do not have access to particle trajectory module).

Thanks in advance.

David Rohrbach
1 Reply Last Post Sep 18, 2017, 1:39 p.m. EDT
Robert Koslover Certified Consultant
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Posted: 7 years ago Sep 18, 2017, 1:39 p.m. EDT
Updated: 7 years ago Sep 18, 2017, 3:23 p.m. EDT

If all you want to know is the E and H fields that will be produced, and if you know the current density and charge density of the beam in question, then you should be able to introduce those two quantities (scalar-field volume charge density and vector-field volume current density) as functions of position.

Comsol Multiphysics is not a particle-in-cell (PIC) code. The particle-tracking module (unless it has been changed since I last heard) simply tracks the motion of hypothetical charged particles through the fields; it does not solve self-consistently for the EM fields (E & H) and particle motions (spatial and velocity distributions) together. For the latter, you should get a PIC code (or perhaps a specialized e-beam code). But again, if you already KNOW the charges and the spatial current density produced by their motion, you can enter those as input conditions (charge density, current density) to the problem and solve for the overall fields, along with the contributions to those fields from any other field sources in your problem.

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Scientific Applications & Research Associates (SARA) Inc.
www.comsol.com/partners-consultants/certified-consultants/sara
If all you want to know is the E and H fields that will be produced, and if you know the current density and charge density of the beam in question, then you should be able to introduce those two quantities (scalar-field volume charge density and vector-field volume current density) as functions of position. Comsol Multiphysics is not a particle-in-cell (PIC) code. The particle-tracking module (unless it has been changed since I last heard) simply tracks the motion of hypothetical charged particles through the fields; it does not solve self-consistently for the EM fields (E & H) and particle motions (spatial and velocity distributions) together. For the latter, you should get a PIC code (or perhaps a specialized e-beam code). But again, if you already KNOW the charges and the spatial current density produced by their motion, you can enter those as input conditions (charge density, current density) to the problem and solve for the overall fields, along with the contributions to those fields from any other field sources in your problem.

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