Heating a bulk medium

A system comprising:

• two or more electrodes spaced apart from one another and coupled to a bulk medium;
• power control means coupled to the electrodes and configured to generate an AC current along a first current path through the bulk medium between the electrodes at a frequency greater than 1 kHz and less than 300 GHz;
• and
• a second current path positioned proximate to a surface of the bulk medium and along the first current path through the bulk medium,
• wherein the power control means shapes a density of the AC current within a depth of the bulk medium by tuning a skin-depth of the AC current, and
• wherein the power control means shapes the density of the AC current in a direction across the first current path by supplying a second current to the second current path to tune a proximity effect of the AC current.

An aircraft de-icing and anti-icing system comprising:

• two or more electrodes spaced apart from one another and coupled to a portion of an aircraft;
• a power control system coupled to the electrodes and configured to heat the portion of the aircraft by shaping a density of current along a current path through the portion of the aircraft between the electrodes by:
• generating an AC current along a current path through the portion of the aircraft between the electrodes and at a frequency between 1 MHz and 50 MHz, wherein the frequency causes the density of the AC current to be shaped in a first direction by tuning a skin-depth of the AC current along the current path;
• and
• providing a second current path positioned along at least a portion of the current path through the portion of the aircraft and within a proximity of 10 cm of a surface of the portion of the aircraft, wherein the proximity of the second current path to the surface of the portion of the aircraft causes the density of the AC current to be shaped in a second, different, direction by tuning a proximity effect of the AC current along the portion of the current path.