ALT Diagram showing three thermal transport systems. All have a heater shown by a rectangle that is red on the left and blue on the right. On the right is a yellow block labeled heat sink. Green arrows labeled H show the external magnetic field. On each, blue arrows labeled J show the thermal current pointing from the red side to the blue side of the rectangle. The far left system is labeled conventional and shows H pointing up. The middle is labeled planar-parallel and shows H pointing the same direction as J. The right is labeled planar perpendicular and has H pointing along the edge of the rectangle down and to the right.