  Given their small mobility coefficient in liquid argon with respect to the
electrons, the ions spend a considerably longer time in the active volume. We
studied the effects of the positive ion current in a liquid argon time
projection chamber, in the context of massive argon experiments for neutrino
physics. The constant recombination between free ions and electrons produces a
quenching of the charge signal and a constant emission of photons, uncorrelated
in time and space to the physical interactions. The predictions evidence some
potential concerns for multi-ton argon detectors, particularly when operated on
surface
