Modular print head assembly for plasma jet printing

An apparatus for printing, comprising:

• (i) a plasma module for generating a plasma discharge, wherein the plasma module comprises a dielectric tube, a first electrode having a first surface area, and a second electrode having a second surface area, wherein the first electrode and the second electrode are configured to move along the length of the dielectric tube;
• and (ii) a detachable fluid assembly comprising a dielectric spacer and a cartridge, wherein a proximal end of the dielectric spacer is configured to be attached to or detached from a distal end of the plasma module, and a distal end of the dielectric spacer is coupled to a proximal end of the cartridge, wherein the cartridge comprises an ink inlet, an ink outlet, an ink reservoir, a piezo atomizer, a perforated plate, a lip, or a combination thereof, and wherein the dielectric spacer of the fluid assembly has a length that is (i) greater than a distance between respective centers of the first electrode and the second electrode in the plasma module, and (ii) between 5 millimeters (mm) to 216 mm.