A voltage scale for electro-thermal runaway

A voltage scale, V_s that characterizes electro-thermal runaway, is deduced from the heat conduction equation, V_s = √k/σ´₀, where k-is the thermal conductivity and σ´₀ is the rate of change of the electrical conductivity with respect to temperature. V_s depends only on material properties and is independent of geometry and the operating voltage. V_s measures the intrinsic tolerance of the material to electro-thermal instability. Numerical values of V_s are consistent with the well-known properties of several common materials.