On the thermodynamic origin of energy principles in plasma physics

Using the methods of non-equilibrium thermodynamics, we show that the energy principles of plasma stability theory have a common thermodynamic origin. A Lyapunov function, which physically has the meaning of an entropy excess, can be unambiguously constructed under the proviso that no circulatory forces operate in the plasma. Explicit calculations are made which reproduce well-known results applicable to widely different plasma models.