The heat ray is a weaker version of the laser since it cannot rotate and it can only aim straight. Its effect on mobs and blocks are the same.
It has no restrictions on speed or torque and needs a microturbine's (2.097 MW) worth of power to function.
The heat ray is required in the Hydrogen Preheater multi-structure. This is to heat up the Hydrogen Preheater in the center to create plasma.