You need to consider the UVs of your sprites, and the screen align method, your rays should run down the Y axis for a rectangle/square/velocity aligned sprite…placing them @ the angle of your window won’t quite work…you can put your particles in local space, and then rotate the emitter to align them.
There may be good reasons to use particles for this, easy to get camera facing etc. working…but in terms of GameThread time etc. etc. you will spend less update time using static meshes.
There are a few basic material tricks here…
Lesson_03 goes into near camera fading, you can combine this with Depth Fade and other techniques to fade the mesh at differing view angles.