The present invention relates to an aerosol-generating system comprising a liquid storage portion for storing liquid aerosol-forming substrate, wherein the liquid storage portion comprises a movable wall and an outlet, a vaporiser comprising a heating element having a structure defining an open-ended internal passage for heating deposited liquid aerosol-forming substrate, a pump configured for delivering liquid aerosol-forming substrate from the outlet of the liquid storage portion to the internal passage of the heating element, the pump comprising a micro stepper motor with a drive shaft that is configured to rotate for a predetermined amount upon performing one step of the micro stepper motor, a piston connected to the movable wall, and a lead screw connecting the drive shaft to the piston and configured to translate a rotation of the drive shaft into an axial movement of the piston and a corresponding axial movement of the movable wall, wherein the vaporiser is configured for heating the delivered liquid aerosol-forming substrate in the internal passage to a temperature sufficient to volatilize at least a part of the delivered liquid aerosol-forming substrate. The present invention further relates to a cartridge for an aerosol-generating system, wherein the cartridge comprises the liquid storage portion, the piston, and the lead screw. The present invention further relates to a method for generating aerosol.La présente invention concerne un système de production d'aérosol comprenant une partie de stockage de liquide permettant de stocker un substrat formant un aérosol liquide, ladite partie de stockage de liquide comprenant une paroi mobile et une sortie, un vaporiseur comprenant un élément chauffant ayant une structure délimitant un passage interne à extrémité ouverte permettant de chauffer ledit substrat formant un aérosol liquide déposé, une pompe conçue pour distribuer un substrat formant un aérosol liquide à partir de la sortie de la partie de stockage de li
