An analytical method for calculation of the critical energy of composite
superconductors based on the theory of minimum propagating zones is
presented. Both quasi-stationary minimum propagating zones and transient
propagating zones are considered. The method, resolving itself into multiple
integration, does not require the temperature field in the conductor to be
determined. Such an approach facilitates dealing with cases allowing for
temperature-dependent conductor properties and for the full boiling
characteristic of the coolant. Formulae for the critical energy with regard
to nucleate and film boiling are derived and sample calculations are performed.
The results show that under good cooling conditions the enthalpy increase in
the quasi-stationary minimum propagating zone approximately equals the minimum
heat content in transient propagating zones.