through holes per square centimeter a total perimeter length of all the straight through holes of the device 1900 per square centimeter is preferably at least two centimeters fig7 shows an embodiment of an nmset or related device 700 with a parabolic geometry in this embodiment alternating hot layers 702 and cold layers 701 are stacked in the illustration each hot layer 702 and cold layer 701 has a straight through hole all the holes are aligned the hole in each hot layer 702 has the similar size as the hole in the cold layer 701 immediately above and is smaller than the hole in the cold layer 701 immediately below each cold layer 701 is colder than its immediate adjacent hot layers 702 and each hot layer 702 is hotter than its immediate adjacent cold layers 701 a surface 702 a of each hot layer 702 which has a surface normal in the u2212 y direction is exposed all the holes collectively form a nozzle with a contour of a parabolic surface this geometry minimizes shared bases between the hot and cold layers however because nmset or related device may not substantially increase the energy of the gas the increasing hole diameter may result in a drop in gas pressure at the edges this can create strong vortexes near the lower aperture which reduce total efficiency nmset with the parabolic geometry can be adiabatic or isobaric but not both an approximation of gas flow in nmset or related device with the parabolic geometry is shown in.