is there anyway to add some thickness on beem particles ? its like a plane now
No, you can add additional planes but you can’t make it volumetric.
This gave me issues as well before, beam particles can only be flat which works fine for beams that are far away, perpendicular to the camera vector, or really small. Larger ones are visibly flat and it looks pretty bad. If you want a 3D beam you could just use a mesh (spline mesh, especially), however depending on the situation that might not be feasible (also going to be more taxing on your hardware, I imagine).
use 2 beam particles and have the 2nd one be rotated by 90 degrees maybe? (so its like an X.
thanks Acds , actually i used beam for start fadein line from start to end point and its good because there is also speed control for that , i think it will be so hard to make this via spline mesh
unfortunately you cant rotate beem particle