# Discussion Forum

## how to plot a charge distribution pictures by RF model？

thanks for reading. i want to know how to plot a charge distribution plot in RF model ,and it may look like that picture i upload follow,possitive and negative charges represented by red and blue .!

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chase the lust given by myself

5 Replies Last Post Dec 4, 2019, 12:41 AM EST

Posted: 5 days ago

Try to express charge density with built-in field variables in the RF-module.

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ZHANG, Pu
School of Physics,
Huazhong University of Science and Technology

Posted: 5 days ago

Try to express charge density with built-in field variables in the RF-module.

thanks for answering. i tried to find the charge density variable when plot ,but failed .i can only find some variables about current density in the expression node under rf module.could you give me more details about the charge density variables and where i can find it . thank you very much!

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chase the lust given by myself

Posted: 4 days ago
Updated: 4 days ago

For a conducting surface in air or vacuum, you could plot (nx * emw.Ex + ny * emw.Ey + nz * emw.Ez) * epsilon0_const which is the surface charge density that follows from Gauss' law.

Posted: 4 days ago

For a conducting surface in air or vacuum, you could plot (nx * emw.Ex + ny * emw.Ey + nz * emw.Ez) * epsilon0_const which is the surface charge density that follows from Gauss' law.

thank you very much ，your advices help me a lot. your method inspires me to try that expression（d（Ex，x）+d（Ey，y））to plot a 2d distribution.and i got a picture attached. thank you again ，you really helped me!

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chase the lust given by myself

Posted: 4 days ago

For a conducting surface in air or vacuum, you could plot (nx * emw.Ex + ny * emw.Ey + nz * emw.Ez) * epsilon0_const which is the surface charge density that follows from Gauss' law.

thank you very much ，your advices help me a lot. your method inspires me to try that expression（d（Ex，x）+d（Ey，y））to plot a 2d distribution.and i got a picture attached. thank you again ，you really helped me!

you see,in the picture the current flow from red to blue :-)

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chase the lust given by myself