Hirst Magnetic Instruments Ltd. can design and manufacture a wide range of electromagnets. Electromagnets are built into the Hirst range of Vibrating Sample Magnetometers (VSM's) and Permeameters (ARP's).
An electromagnet consists of an iron cored framework with one or two windings around the core. The windings are driven by DC or AC power supplies to provide a magnetic field between the pole pieces of the electromagnet. Electromagnet can be supplied with interchangeable pole tips to provide high fields over smaller areas.
Hirst can supply the appropriate power supply to match the Electromagnet or it can be supplied by the customer.
For some applications it is necessary to provide adjustment of the gap between the pole pieces. This allows samples of different thicknesses to be tested or processed. For this facility the adjustment is manually achieved with an adjusting wheel and hand clamp.
Due to the permeability of the iron core, there is a practical limit of about 2.0 Tesla of the field that can be generated in the poles of an electromagnet. This makes testing of rare earth magnets usually unsuitable for electromagnets. Air Cored coils driven from a capacitor bank is the usual technique for these higher fields as described in our PFM section.
Most electromagnets are made with an outer rectangular iron
framework and central stems around which the coils are fitted. These
stems form the pole pieces where controlled magnetic field is
generated. C shaped electromagnets are another popular
configuration. Hirst can design and manufacture electromagnets to
suit any particular
configuration that a customer requires.