Gas is expanding free into the initially vacuumed shock tube (from left to right, not drawn). Once it reaches the opposite (right) end, the reflected shock wave propagates back (to the left), on the expanding gas, effectively stopping it, and leaving non-isentropically compressed gas behind. Its temperature is significantly higher compare to the original one. Average temperature of all gas in the tube, after the equilibrium is achieved, is higher in kappa (Cp/Cv) times, because of the work performed by the ambient gas. This computation in Turbo Pascal 6, justifies the non-isentropic gas compression technique, disclosed the PhD thesis.