A multi-jet plasma source is being developed for large area treatment of surfaces with atmospheric pressure plasma for applications including plasma medicine and surface functionalization. The multi-jet source is a dielectric tube, capped at the end, with a row of holes aligned on one side. Helium flows through the tube and out the holes, where plumes of the He mix with ambient humid air. An ionization wave (IW) begins at a powered electrode upstream of the holes, propagates along the tube and, as passing each hole, launches a separate, secondary ionization wave (SIW) through the hole. The fundamental properties of this system have been investigated using nonPDPSIM, a 2-D plasma hydrodynamics model. The propagation of the SIWs depends on the diameter of the holes, helium flow rate, and voltage polarity. The hole diameter determines the velocity of the SIW as it passes through the holes by controlling the angle of the electric field within the holes. There is an inherent asymmetry in launching the SIW due to charging of one side of the hole by the propagating primary IW. A higher helium flow rate results in a larger region of purer helium outside of the tube, extending the distance the SIW can propagate outside of the hole before encountering air. Positive voltage polarity produces a more uniform plasma within the tube, and increases the intensity of the SIW outside of the tube. Scaling laws will be discussed for and comparisons made to experimental ICCD imaging of the primary IW and SIW, for which there is good agreement.