Technologies are described for applying electrical energy according to a physical extent of a combustion reaction, which may include: supporting a combustion reaction at a fuel source; sensing a physical extent of the combustion reaction with respect to a plurality of different locations of a plurality of electrodes; and applying electrical energy to the combustion reaction via at least one of the plurality of electrodes responsive to the physical extent of the combustion reaction. Sensing the physical extent of the combustion reaction may include receiving a sensor signal corresponding to the physical extent of the combustion reaction.