OK so all is explained !
the reason we want to fixe 18mA is that our device under test consums “a lot” in the start phase (I suppose that, if current goes above the limite range, Joulescope not only clips the current but that there is also perturbations on the output voltage. But maybe I’m wrong ? ).
After this starting phase, current decrease a lot and we want to mesure it with a precison better than 1 µA, so effectively we’ll change the i-range to 1.8 mA or below.
On this resolution topic, we can noticed on the Current measurement specifications that for a given range resolution is better than accuracy: we had interpreted this by : résolution = differential linearity / accuracy = integral (absolute) linearity . Is our interpretation OK ?
Last thing about this i_range topic : we can see on pictures above that current shape change a lot with i-range → it means certainly that Jouescope integrates current with a time constant depending of i_range (certainly due to noise reduction reasons (?)). If it’s the case could it be possible for the user to change this time constant for a given i-range if he wants to have a better idea of the real current’s shape ( even if the noise will be increasedof course) ?