I have a question about the saturation mode. The cross-section of an NMOS transistor in saturation mode is usually drawn like this:
But it seems to me that there can be no current from source to drain in this case (because there is no contact between the channel and the drain). From the diagram that plots \$V_{\text{DS}}\$ against \$I_{\text{D}}\$, it can be seen that in saturation mode, there is a current (it just doesn't increase when we increase \$V_{\text{DS}}\$).
So what is going on in saturation mode?