Assimilation chamber

From Memory Alpha, the free Star Trek reference

An assimilation chamber is a section of Borg vessels where assimilations are performed.

The chamber is used for the second phase of assimilation, following the injection of nanoprobes. It is here where complicated prosthetics such as replaced limbs are installed. Special assimilations are also performed in these chambers such as Locutus of Borg. (TNG: "The Best of Both Worlds, Part II")

Typically a number of victims would be transported to the chamber, and be forced to wait while they were assimilated one by one. The chamber is surrounded by force fields to prevent escape. (VOY: "Dark Frontier", "Collective")