A heater and /or cooler chamber (1, 71) configured for treating a batch of more than one workpiece, which are sheet-shaped, drum- skin like shaped in a frame, band or plate shaped having each a pair of two-dimensionally extended surfaces and a thickness D of 0.01 mm ≤ D ≤ 5 mm, especially of such equal workpieces, thereby especially of substrates or wafers, all workpieces with structured or unstructured extended surfaces and single or multi-layered, especially as a degasser heater-chamber for such a batch, comprising: - a heat storage block or chunk (3, 72) made of one single metal piece or of more than one thermally narrowly coupled metal parts, thermally behaving in common only negligibly different from such equal single piece metal block or chunk; - said block (3, 72) comprising more than one parallel and stacked slit-pockets (7, 74) stacked one upon the other, each dimensioned to accommodate a single of said workpieces therein and extending along a slit-pocket plane (Ep); - in each of said slit-pockets (7, 74) a workpiece support for a workpiece; - each slit-pocket (7, 74) having at least one workpiece handling opening; - each slit-pocket (7, 74) being tailored to surround one of said workpiece, applied on its workpiece support, in a noncontact manner, the height h of each of said slit-pockets (7, 74), perpendicular to said slit-pocket planes (Ep) and along not less than 30% of the extent surface area of said slit-pockets (7, 74), considered parallel to said slit-pocket planes (Ep) being: 2.5 mm ≤ h ≤ 50 mm - the at least one workpiece handling openings of said slit-pockets] (7, 74) being operatively connected to a door arrangement controllably freeing and covering the respective workpiece handling openings with respect to an atmosphere outside said block (3, 72); - at least one heater and/or cooler interface to said block (3, 72); - a heater and/or cooler arrangement provided in or along at least one distinct outer area of said block (3, 72), said interface being then the outer area of said block (3, 72). - a heat storage block or chunk (3, 72) made of one single metal piece or of more than one thermally narrowly coupled metal parts, thermally behaving in common only negligibly different from such equal single piece metal block or chunk; - said block (3, 72) comprising more than one parallel and stacked slit-pockets (7, 74) stacked one upon the other, each dimensioned to accommodate a single of said workpieces therein and extending along a slit-pocket plane (Ep); - in each of said slit-pockets (7, 74) a workpiece support for a workpiece; - each slit-pocket (7, 74) having at least one workpiece handling opening; - each slit-pocket (7, 74) being tailored to surround one of said workpiece, applied on its workpiece support, in a noncontact manner, the height h of each of said slit-pockets (7, 74), perpendicular to said slit-pocket planes (Ep) and along not less than 30% of the extent surface area of said slit-pockets (7, 74), considered parallel to said slit-pocket planes (Ep) being: 2.5 mm ≤ h ≤ 50 mm - the at least one workpiece handling openings of said slit-pockets] (7, 74) being operatively connected to a door arrangement controllably freeing and covering the respective workpiece handling openings with respect to an atmosphere outside said block (3, 72); - at least one heater and/or cooler interface to said block (3, 72); - a heater and/or cooler arrangement provided in or along at least one distinct outer area of said block (3, 72), said interface being then the outer area of said block (3, 72).