Motion requirements in mass spectrometry
Mass spectrometry systems often require precise motion and manipulation within a high vacuum. Rotary feedthroughs are needed to transfer motion into the vacuum chamber without compromising the seal. This creates a specific engineering problem: how to rotate a shaft while maintaining a perfect vacuum seal. Ferrofluid, or magnetic fluid, feedthroughs are one established solution. They use a magnetically held fluid to form a dynamic seal around a rotating shaft.
Multi-axle and hollow shaft configurations
Basic single-shaft designs are common, but applications like sample introduction or ion optics manipulation can demand more complex motion. This has led to the development of multi-axle feedthroughs. Industry product listings show dual axle and tri-axle ferrofluid vacuum feedthroughs. A dual axle device uses two coaxial shafts, while a tri-axle version uses three. Some manufacturers also list models with three non-coaxial shafts. Another variation is the hollow shaft feedthrough. These allow for the passage of light, fluids, or electrical wires through the center of the rotating shaft. Compliant mount versions with hollow shaft diameters of 50 mm and 75 mm are commercially available, as are imperial-sized models like the 0.5-inch and 1-inch variants.
Construction and materials for high vacuum
The operational environment dictates construction. For mass spectrometry and other high-vacuum processes like plasma PVD film deposition, materials must have low outgassing. Stainless steel is the standard housing material for these feedthroughs. The magnetic fluid itself must be formulated to withstand the vacuum pressure without evaporating or degrading. Manufacturers with over 30 years of experience in magnetic fluid feedthroughs point to ongoing research to refine these sealing capabilities. The goal is to meet evolving customer needs for reliability and performance in demanding applications.
Integration and application notes
Selecting the correct feedthrough involves matching the mechanical specifications to the system's motion requirements. The number of shafts, their alignment (coaxial or not), and whether a hollow shaft is needed are primary considerations. For OEM applications in vacuum product manufacturing, custom feedthrough designs are sometimes developed to solve unique motion challenges. In mass spectrometry, these components are part of a larger assembly of valves, fittings, and custom chambers. Their reliable operation supports the consistent sample introduction and ion manipulation needed for accurate analytical results.
We supply a range of ferrofluid feedthroughs, including dual axle and hollow shaft models, for these technical applications.