Aerosol-generating system comprising a fluid permeable susceptor element

A cartridge for an electrically heatable aerosol-generating system, the electrically heatable aerosol-generating system comprising an aerosol-generating device, the cartridge configured to be used with the aerosol-generating device, wherein the aerosol-generating device comprises a device housing defining a cavity configured to receive at least a portion of the cartridge, an inductor coil positioned around or adjacent to the cavity, and a power supply connected to the inductor coil and configured to provide a high-frequency oscillating current to the inductor coil;

• the cartridge comprising:
• a cartridge housing configured to engage the device housing and containing an aerosol-forming substrate, the cartridge housing having an external surface, at least a portion of the external surface being formed by a fluid permeable susceptor element, the fluid permeable susceptor element being electrically isolated from any other electrically conductive components;
• a first capillary material in the cartridge housing in contact with the fluid permeable susceptor element;
• and
• a second capillary material in the cartridge housing in contact with the first capillary material,
• wherein the first capillary material has a higher thermal decomposition temperature than the second capillary material.