The formation of Z-pinch dynamic hohlraums (ZPDHs) can be regarded as a two-phase process consisting of the energy thermalization and the shock propagation. Once the Z-pinch plasma impacts onto the convertor, the energy thermalization begins with two shocks generated counter-propagating in the Z-pinch plasma and the convertor, and ends when all the Z-pinch plasma has been subjected to the shock. Focused on the energy thermalization process, a simple model is built to investigate the interaction between the Z-pinch plasma and the convertor, and the matching mass ratio between them can be found by optimizing the matter temperature. The matching mass ratio is affected little by the convertor radius but sensitive to the initial mass and radius of the Z-pinch plasma. The matching relationship at higher drive current is also investigated and it is found that the matching mass ratio is mainly determined by the initial radius of the Z-pinch plasma. The application of the model to the PTS facility brings some suggestions to optimize the ZPDH.
