Top: Midplane ionisation rate profile at t=0, 1, and 5 Myr (increasingly dark blues, evolution indicated by arrow) for fiducial models around TTS (left) and VLMSs (right). The TTS models are compared to observationally estimated values for individual sources (red and yellow colours) and the range and median for the exoALMA program (Trapman et al. 2025). The black horizontal line on each plot represents the floor due to SLRs and the vertical dotted line shows the location of the CO snowline. Bottom: Surface densities of the gas at the times indicated in the top panels. The horizontal line shows the assumed 96 g cm⁻² penetration depth of CRs.