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Field Enhancement

Posted 8 feb 2024, 01:06 GMT-5 Electromagnetics, Wave Optics, Equation-Based Modeling 1 Reply

Gopika Gopalakrishnan
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What is the procedure for getting the field enhancement of a nanogap?

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1 Reply Last Post 8 feb 2024, 09:55 GMT-5
Robert Koslover Certified Consultant
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Posted: 3 months ago 8 feb 2024, 09:55 GMT-5
Updated: 3 months ago 8 feb 2024, 09:59 GMT-5

I don't know anything specific about nanogaps, but if/when I want to compute the electric field on/around some pointy geometric entity, I employ a relatively fine mesh on the boundary, compute the fields, and then inspect/plot the fields in that region. Meshing makes a difference here. If you need high confidence, keep refining the mesh, constraining it to be high quality, and re-running the model until the field value at the points/edges/surfaces in question stops changing too much. If you have the time and memory, then maybe consider a higher element discretization (e.g., cubic or quadratic instead of linear). You may also see differences in values plotted if you turn on/off various degrees of smoothing in the plot. Inspect the plot in detail without smoothing, if you want to check if your mesh seems sane/fine enough. Strong gradients in field between adjacent mesh elements may be cause for additional attention, and likely finer meshing, there. You don't have to mesh everywhere super-finely, just where the (if serious) field enhancement occurs. And you can usually guess where that is going to be (or is likely to be) in advance. I also sometimes employ probes (surface or volume) to quantify or locate maximum fields, since the max field is often of interest when studying field enhancement. There are also analytic approximations / sanity checks you can apply (you know, the sorts of things people used to do, such as conformal mapping, before these wonderful codes and computers made our lives so easy).

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I don't know anything specific about nanogaps, but if/when I want to compute the electric field on/around some pointy geometric entity, I employ a relatively fine mesh on the boundary, compute the fields, and then inspect/plot the fields in that region. Meshing makes a difference here. If you need high confidence, keep refining the mesh, constraining it to be high quality, and re-running the model until the field value at the points/edges/surfaces in question stops changing too much. If you have the time and memory, then *maybe* consider a higher element discretization (e.g., cubic or quadratic instead of linear). You may also see differences in values plotted if you turn on/off various degrees of smoothing in the plot. Inspect the plot in detail without smoothing, if you want to check if your mesh seems sane/fine enough. Strong gradients in field between adjacent mesh elements may be cause for additional attention, and likely finer meshing, there. You don't have to mesh everywhere super-finely, just where the (if serious) field enhancement occurs. And you can usually guess *where* that is going to be (or is likely to be) in advance. I also sometimes employ probes (surface or volume) to quantify or locate maximum fields, since the max field is often of interest when studying field enhancement. There are also analytic approximations / sanity checks you can apply (you know, the sorts of things people used to do, such as conformal mapping, before these wonderful codes and computers made our lives so easy).

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