I want to recreate a built-in engine texture

The attached image is a window of a texture properties and look.

The problem i’m having is that i want to recreate this texture using paint.net or any similar software.

The reason i’m saying “Recreate” is because i can’t seem to find the source file for the texture in the engine in my computer, or perhaps i don’t know how to get to it.

I’m assuming that it’s built-into the engine, that’s why i can’t get to the source file in my computer.

If i have the source file for that texture, that should be enough too.

Why not just use the already built-in texture?
Well, i did use it, but i need to have smaller "glowy"particles similar to it that i will use in a texture.
The “Glowy” or rather gradually transparent parts of that texture is what i need.
The texture in the engine is called " T_EV_FogSheet_Falloff_03 "

I need to know this, as it will help me do certain essential visual effects for my game.

PS: No, I did not confuse this with the particle system, this has nothing to do with the particle system.

you could make a effect like that in a material with a radial gradient. or if you really want to recreate it in a external program you could use a brush with falloff or draw a circle and then use a blur.