A displacer for adjusting a level of a liquid cryogen in a cryostat. The displacer including an expandable member at least partially defining a sealed chamber. The expandable member being configured to transition from a collapsed state where the sealed chamber has a smaller volume to an expanded state where the sealed chamber has a larger volume. The displacer includes a first end piece attached to a first end of the expandable member and a second end piece attached to a second end of the expandable member.