Hey Ron, thanks for your reply
well when the transistor is turned on, the current through the transistor is increasing, thus IL as well => VL increases and since VD = 12V - VL ... VD ramps down until ID becomes constant, in that case VL = L*dIL/dt = 0 since the current is a constante
In addition is VD was equal to zero, ID will be equal to zero too, isn't it?
Concerning the breakdown, if I can reduce the current through the Drain by adding a resistor at the drain, won't it be ok?
thanks for you help
Jay