Piston effect in a supercritical fluid sample cell : A phenomenological approach of the mechanisms Y. Garrabos, A. Dejoan, C. Lecoutre, D. Beysens, V. Nikolayev et R. Wunenburger J. Phys. IV France, 11 PR6 (2001) Pr6-23-Pr6-34 DOI: 10.1051/jp4:2001603