Hello to everyone!

I am trying to understand an electrostatic issue. The scenario is, that we have a plate capacitor filled with vacuum (d=10cm), where a thin dielectric sample is placed on the bottom plate (ε=10, 1x1cm2 and 0,5mm thick). The applied voltages are -400V @ bottom plate and 0V @ top plate.

I simulated the problem with ANSYS Maxwell. Firstly, I visualized the E-Field around the sample (1) and secondly the E-Field on the dielectric surface itself (2).

(1) As you can see on the images, the E-Field shows edge effects leading to a reduced E-Field magnitude around the edges of the sample (green-blue), while above the center of the sample it is increased (yellow-orange).

(2) Inversely, looking at the sample surface itself, we can see that the E-Field in the center is weaker (dark blue) than at the edges (light blue-green). So the other way around...

I understand that the dielectric weakens the initial E-Field in general due to induced polarization. But what could be the reason for the lateral differences in E-Field magnitude between the edge areas (higher magnitude) and the center (lower magnitude)?

Does an increased E-Field in the edge areas of the dielectric surface mean, that there are more surface charges?

Thank you in advance!