Enhanced yield blood processing systems with angled interface control surface

A chamber for rotation about a rotational axis to separate blood components comprising

• first and second spaced apart side walls forming a separation zone, the second wall being farther from to the rotational axis than the first wall,
• an inlet passage to convey blood into the separation zone for separation into a first region of cellular components along the second wall, a second region of plasma along the first wall, and an interface region between the first and second regions,
• an outlet passage to convey the second region of plasma from the separation zone, the outlet passage having an axis, and
• an interior wall extending from the second wall into the separation zone including a first surface spaced from the first wall adjacent the outlet passage, the space between the first surface and the first wall comprising a constricted passage in fluid communication with the outlet passage, the interior wall including a second surface that tapers from the first surface away from the outlet passage to permit passage of the second region of plasma through the constructed passage to the outlet passage while retarding passage of the interface region and the first region of cellular components through the constricted passage, the tapered second surface having a major axis that is oriented at a non-parallel angle with respect to the axis of the outlet passage.