The Gadmeer device is a device created by the Gadmeer. Its function is unknown.
When Daniel Jackson returned to the Gadmeer terraformer to talk to Lotan, he discovered him interfacing with this device. The field disengaged a few seconds later, though it is unknown if this was triggered by Daniel's entering the room, Lotan, or an automated timer. (SG1: "Scorched Earth")
It seems as though the device could be a way of healing Lotan after his body has undergone some form of damage, as he was seen using it just before he told Daniel Jackson that he had taken a chance to breath the terraformed air and it was "Not good."