Magnetic Rotary Motion Feedthrough Units - Rigaku

Excellent Magnetic-field Resistance
Rigaku offers a magnetic rotary seal unit featuring high resistance to external
magnetic fields. This feature comes from a magnetic circuit unique to Rigaku
as well as high-energy rare earth magnets.
Magnets are arranged in opposition to each other (SN-NS) to produce the magnetic field distribution
shown in Fig.1. The magnetic flux distribution changes abruptly at the edge of the pole pieces
between S-S and N-N, and magnetic fluid converges towards the center of the magnetic flux (from
both sides). If a magnetic circuit has only one magnet, an ideal convergence cannot be obtained
because the magnetic flux will be dispersed. The magnets have excellent characteristics, such as a
strong resistance to external magnetic field, and a large maximum energy product (BH) in
comparison with conventional ferrite and alnico magnets.
Fig. 1: Conceptual drawing of
magnetic flux distribution
Fig. 2: Test results on magnetic-field resistance
of magnetic rotary seal unit
other manufacturers
Pressure (Pa)
Occurrence of leakage
External magnetic field (T)
Magnetic field leakage
There is very little leakage of magnetic field,
owing to Rigaku's unique magnetic circuitry.
The seal can be used in equipment that is
susceptible to magnetic field leakage, such as
that from an electron beam.
Magnetic field leakage
Magnetic field
leakage to
the VAC side
(T)
Other manufacturers
Distance (mm)
Tel: 603-890-6001 Fax: 603-890-6016 www.rigaku.com
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