Chell uses a micro-resonator
A micro-resonator was a tool used to degauss relatively small devices. For larger objects, a magneton scanner could accomplish the same task.
In 2371, as part of a crash course in Starfleet training, Tuvok had Crewman Chell degauss a USS Voyager transporter room with a micro-resonator to learn "patience". Tuvok estimated it would take approximately 26.3 hours to complete; Torres stated that the magneton scanner would take five minutes. (VOY: "Learning Curve")
The use of a micro-resonator, instead of the magneton scanner, for this chore is analogous the 24th century equivalent of using "a toothbrush to clean a floor."
The prop device seen was later re-used as a scanning device in the second season episode "Resistance".