Auroral field-aligned currents are of key importance for the electromagnetic coupling and the energy transport in the magnetosphere-ionosphere system. Using Swarm multi-spacecraft magnetic and electric field measurements and multi-point reconstruction methods for planar structures in geospace, we are going to analyze and study in detail the fine structure of sheets of auroral field-aligned currents. Preferred spatial scales are expected to help identifying auroral acceleration mechanisms. Our results will be compared with current profiles of other force-free plasma structures in the Earth's space environment such as directional discontinuities in the solar wind. With our collaboration partners we plan to make use of Swarm magnetic and electric field measurements in the auroral zone for quantifying height-integrated Joule heating rates and estimating the energy deposition into the upper atmosphere.