Subspace isolation field

From Memory Alpha, the free Star Trek reference

A subspace isolation field (or subspace force field) is a localized force field that contains its own pocket of subspace.

The away team of the USS Enterprise-D used such subspace force fields to stay in their space-time continuum when they explored the Devidians on Devidia II. (TNG: "Time's Arrow", "Time's Arrow, Part II")

In 2369 Captain Picard suggested the use of subspace force fields to beam on board the Enterprise-D which was trapped in a temporal fragment. Geordi La Forge, agreed but mentioned that they needed a phase discriminator for this theory to succeed . Data told them that the emergency transporter armband contained such a phase discriminator. La Forge modified several armbands and the away team could then move on the Enterprise-D without creating a temporal disturbance. (TNG: "Timescape")