A new closed/open volumetric receiver concept for parabolic trough collectors (test results) B. Hoffschmidt, R. Pitz-Paal, M. Böhmer, P. Rietbrock, C. Koeppen et D. Ulber J. Phys. IV France, 09 PR3 (1999) Pr3-557-Pr3-562 DOI: 10.1051/jp4:1999388