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Debugging Plasma Models and Using the Plasma, Time Periodic Interface

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In Part 3 of our course onmodeling nonequilibrium plasmausing COMSOL Multiphysics^®and the Plasma Module, we begin with a demonstration of debugging a plasma model. Through the demonstration you will learn how to resolve some common error and warning messages (mentioned previously inPart 2). Following this, we take a closer look at one of the specialized physics interfaces for plasma modeling, thePlasma, Time Periodicinterface. We provide a detailed introduction to the interface, discuss the applications it is used for modeling, and talk about how it resolves one of the main challenges of capacitively coupled plasma (CCP) modeling.

From there, we highlight several settings in thePlasma, Time Periodicinterface as well as features that can be added through the interface, including:

• Extra dimension settings
• TheMetal Contactfeature
• Options for pulsed discharges
• ThePeriodic Excitationsubnode for dual frequency reactors
• CCP circuits and matching networks
• Specialized study types
  • TheTime Periodicstudy
  • TheTime Periodic to Time Dependentstudy

We then provide a step-by-step demonstration of how tocompute the impedance of a CCP. We first conduct aTime Periodicstudy, then map that solution to the time domain using aTime Periodic to Time Dependentstudy, and, finally, compute the FFT of the time domain solution using aTime to Frequency FFTstudy. We encourage you to follow along in the software — the cross section data that you will need to import is available from the linked Application Gallery entry.

After the demo, there is a brief discussion on when you should use thePlasmainterface and important considerations for when using thePlasma, Time Periodicinterface. We conclude by offering some general plasma modeling tips, covering:

• Why it is best to start with 1D models for these types of applications
• Why and how you should start with simple chemistry species and reactions and then progressively add complexity to build up to complex chemistries
• Using theSpecies GroupandSpecies Constraint Groupfeatures
• Meshing considerations
• Using an auxiliary sweep in your study
• How to adjust solver settings if it is difficult to obtain convergence