Small gap device system and method of fabrication

A thermionic energy converter system, comprising:

• a first electrode comprising a first surface;
• a second electrode comprising a second surface;
• and
• a mesh spacer maintaining a gap between the first and second surfaces;
• wherein:
• the first and second surfaces are arranged facing each other across the gap;
• the mesh spacer electrically and thermally isolates the first electrode from the second electrode;
• the mesh spacer defines a mesh structure comprising a set of vertices and a set of paths connected between vertices of the set, the set of paths comprising a first path and a second path;
• the mesh spacer comprises a set of legs extending substantially along the set of paths, the set of legs comprising:
• a first leg extending substantially along the first path, the first leg comprising a first protrusion that contacts the first surface, the first protrusion protruding toward the first surface from a body of the first leg;
• and
• a second leg extending substantially along the second path, the second leg connected to the first leg via the set of legs, wherein the second leg contacts the second surface;
• and
• the mesh spacer defines a plurality of apertures between legs of the set of legs, wherein, for each aperture of the plurality, a respective first surface normal vector from the first surface to the second surface passes through the aperture and does not intersect the mesh spacer.