Scaling of large area atmospheric pressure plasma jet arrays remains a key challenge due to electrical and hydrodynamical coupling between individual plasma jets. Here, we present a novel means by which to obtain a large-volume large-surface-area atmospheric plasma jet array in helium. The individual jets of the plasma jet array are confined to expand in a secondary jet tube. The secondary jet tube assists the individual jets in mixing to form a single large-volume large-surface-area plasma jet on a downstream substrate. It is envisaged that the present system will facilitate more homogeneous treatment of large surface areas in both surface treatment and plasma medicine applications.