There are two basic methods of producing latent tracks in the foils to be transformed into porous membranes. The fission fragments coming from a thin layer target have an almost isotropic angle distribution. To create an array of latent tracks penetrating the foil, a collimator is normally used.
Modern accelerators provide beams of higher intensities.
The energies of accelerated ions are a few MeV per nucleon. The beams can be pulsing or continuous. To irradiate large areas a scanning beam is normally used. However, the stability of the particle flux from an accelerator is usually lower. Another disadvantage is a higher cost of irradiation.