  Two-phase Cryogenic Avalanche Detectors (CRADs) with GEM and THGEM
multipliers have become an emerging potential technique for charge recording in
rare-event experiments. In this work we present the performance of two-phase
CRADs operated in Ar and Ar+N2. Detectors with sensitive area of 10x10 cm2,
reaching a litre-scale active volume, yielded gains of the order of 1000 with a
double-THGEM multiplier. Higher gains, of about 5000, have been attained in
two-phase Ar CRADs with a hybrid triple-stage multiplier, comprising of a
double-THGEM followed by a GEM. The performance of two-phase CRADs in Ar doped
with N2 (0.1-0.6%) yielded faster signals and similar gains compared to the
operation in two-phase Ar. The applicability to rare-event experiments is
discussed.
