[en] In this note formulas are given which describe the behaviour of the plasma quantities under compression in the presence of transport and α - heating. The deviations from adiabaticity at higher orders are calculated. The formulas are applied to the calculation of the relevant quantities in the compressions - decompressions cycles around the ignition point which allow the temperature control of an ignited plasma. Explicit formulas are given for the temperature excursions, the duration of each side of the cycle and the electric energy and power directly generated in the external coils of the controlling vertical field. The application of these results to the Zephyr experiment and to INTOR is discussed. (orig./GG)