  Liquid metal walls in fusion reactors will be subject to instabilities,
turbulence, induced currents, error fields and temperature gradients that will
make them locally bulge, thus entering in contact with the plasma, or deplete,
hence exposing the underlying solid substrate. To prevent this, research has
begun to actively stabilize static or flowing liquid metal layers by locally
applying forces in feedback with thickness measurements. Here we present
resistive sensors of liquid metal thickness and demonstrate jxB actuators, to
locally control it.
