Apparatus for altering the magnetic state of a permanent magnet

A method of changing the magnetic state of a permanent magnet, said method comprising:

• charging a first charge storage element to a predetermined level;
• discharging said first storage element into a second charge storage element via a magnetic field inducing device to generate a magnetic field pulse;
• discharging said second storage element into said first storage element via said magnetic field inducing device to generate another magnetic field pulse of different magnitude and different polarity than that of said previous magnetic pulse;
• and
• repeating said discharging steps to generate a series ot alternating polarity magnetic field pulses of decreasing magnitude in said device until said permanent magnet has reached a desired magnetic state.

An apparatus for changing the magnetic state of a permanent magnet to a desired magnetic state, said apparatus comprising:

• means for charging a first charge storage element to a predetermined level;
• means for generating a magnetic field pulse by discharging said first storage element into a second storage element via a magnetic field inducing device;
• means for generating another magnetic field pulse of a different polarity and a different magnitude than that of said previous pulse by discharging said second storage element into said first storage element via said magnetic field inducing device;
• said generating means being arranged to be operated alternately to provide a series of alternating polarity magnetic field pulses of decreasing magnitude in said device.

An apparatus for demagnetising a permanent magnet by spiralling it around its hysteresis loop, said apparatus comprising:

• means for generating an electromagnetic field;
• first and second charge storage means connected together and to said field generating means for transferring charge between each other via said field generating means;
• and
• control means for controlling the charging and discharging thereof so as, in use of the apparatus, to cause said field generating means to generate an alternating polarity reducing magnetic field.