Magnetic annealing oven and method

A magnetic annealing oven comprising:

• a) a vacuum chamber formed of non-magnetic material adapted to receive and having disposed therein a heat exchanger formed of non-magnetic material and having first and second compartments, the first compartment having an opening for receiving magnetic media, the second compartment having an airtight volume hermetically sealed from the first compartment and the vacuum chamber;
• b) a vacuum pump connected to the vacuum chamber, the vacuum pump being capable of providing a vacuum of at least 10−7 Torr within the chamber;
• c) a heat transfer gas unit having heat transfer conduits connected to the second compartment of the heat exchanger to form a heat transfer gas circuit hermetically sealed from the vacuum chamber and the first compartment to supply heating and cooling gas to the second compartment, the first compartment being in thermal communication with the second compartment allowing conductive heat transfer between the gas supplied to the second compartment, the first compartment and the magnetic media disposed therein;
• and
• d) a magnet for inducing a magnetic field of greater than 0.25 Tesla in magnetic media disposed in the heat exchanger, the magnet being located exterior to the chamber and positioned to induce the magnetic field along the center line of magnetic media disposed in the heat exchanger.

A magnetic annealing oven comprising:

• a) a vacuum chamber formed of non-magnetic material, the vacuum chamber having an exterior surface, an interior surface, a vacuum port for loading and unloading of magnetic media, and a rear wall;
• b) a door for sealing the vacuum port of the vacuum chamber;
• c) a vacuum pump connected to the vacuum chamber, the vacuum pump being capable of providing a vacuum of at least 10−7 Torr within the chamber;
• d) a heat exchanger formed of non-magnetic material and adapted to receive magnetic media, the heat exchanger:
• having exterior walls, being located within the chamber, and positioned so that there is a gap between the exterior walls of the heat exchanger and the interior surface of the chamber;
• e) a heat transfer gas unit connected to the heat exchanger to form a hermetically sealed heat transfer gas circuit;
• and
• f) a magnet for inducing a magnetic field of greater than 0.25 Tesla in magnetic media disposed in the heat exchanger, the magnet:
• being located exterior to the chamber, spaced away from the exterior surface of the chamber, and positioned to induce the magnetic field along the center line of magnetic media loaded in the heat exchanger.

A oven for annealing of magnetic media comprising:

• a) a vacuum chamber formed of non-magnetic material, the chamber having an exterior surface, an interior surface, an opening through which magnetic media can be loaded and unloaded, and a rear wall,
• b) a door for sealing the opening of the vacuum chamber;
• c) a heat exchanger formed of thermally conductive, non-magnetic material and adapted to receive magnetic media, the heat exchanger having exterior walls and being positioned within the chamber so that there is a gap between the exterior walls of the heat exchanger and the interior surface of the chamber, and adapted for hermetically sealed connection to a heat transfer gas unit external to the chamber;
• d) a magnet capable of inducing a magnetic field of greater than 0.25 Tesla in magnetic media loaded in the heat exchanger, the magnet being located exterior to the chamber, spaced rearwardly of the door in proximity to the heat exchanger, and positioned to induce the magnetic field along the center line of magnetic media loaded in the heat exchanger;
• e) a heat transfer gas unit located external to the chamber and connected to the heat exchanger for providing heat transfer gas to the heat exchanger at high pressure, the heat transfer gas unit being capable of heating and cooling the heat transfer gas consistent with uniform heat transfer to magnetic media;
• and
• f) a vacuum pump for providing a vacuum of at least 10−7 Torr within the chamber, the pump being connected to the chamber.

A oven for annealing of magnetic media comprising:

• a) a vacuum chamber formed of non-magnetic material, the chamber having an exterior surface, an interior surface, an opening through which magnetic media can be loaded and unloaded, and a rear wall;
• b) a door for sealing the opening of the vacuum chamber;
• c) a carrier into which magnetic media can be loaded, the carrier being formed of thermally conductive, non-magnetic material;
• d) a heat exchanger formed of thermally conductive, non-magnetic material and adapted to receive and to cooperate with the carrier to heat and cool magnetic media loaded therein through thermal conductive heat transfer, the heat exchanger having exterior walls and being located within and an integral part of the chamber, with a gap between the exterior walls of the heat exchanger and the interior surface of the chamber, and adapted for hermetically sealed connection to a heat transfer gas unit external to the chamber;
• e) a magnet capable of inducing a magnetic field of greater than 0.25 Tesla in magnetic media loaded in the heat exchanger, the magnet being located exterior to the chamber, spaced rearwardly of the door in proximity to the heat exchanger, and positioned to induce the magnetic field along the center line of magnetic media loaded in the heat exchanger;
• f) a heat transfer gas unit located external to the chamber and connected to the heat exchange for providing heat transfer gas to the heat exchanger at high pressure, the heat transfer gas unit being capable of heating and cooling the heat transfer gas consistent with uniform heat transfer to magnetic media;
• and
• g) a vacuum pump for providing a vacuum of at least 10−7 Torr within the chamber, the pump being connected to the chamber.

A method of magnetic annealing magnetic media comprising the steps of:

• a) providing a magnetic annealing oven, the oven having:
• (i) a vacuum chamber formed of non-magnetic material and adapted to receive and having disposed therein a heat exchanger formed of non-magnetic material, the heat exchanger having first and second compartments, the first compartment being adapted to receive magnetic media, the second compartment having an airtight volume hermetically sealed from the first compartment and the vacuum chamber;
• (ii) a vacuum pump connected to the vacuum chamber, the vacuum pump being capable of providing a vacuum of at least 10−7 Torr within the chamber;
• (iii) a heat transfer gas unit having heat transfer conduits connected to the second compartment of the heat exchanger to form a heat transfer gas circuit hermetically sealed from the vacuum chamber and the first compartment, the conduits supplying heating and cooling gas to the second compartment, the first compartment being in thermal communication with the second compartment allowing conductive heat transfer between the gas supplied to the second compartment, the first compartment and the magnetic media disposed therein;
• and
• (iv) a magnet for inducing a magnetic field of greater than 0.25 Tesla in magnetic media disposed in the heat exchanger, the magnet being located exterior to the chamber and positioned to induce the magnetic field along the center line of magnetic media disposed in the heat exchanger;
• c) sealing the chamber to create a vacuum seal;
• d) ramping up to a vacuum of at least 10−7 Torr within the chamber;
• e) ramping the temperature of the magnetic media up to a target annealing temperature at a rate consistent with uniform heat transfer to the magnetic media;
• f) ramping up the magnetic field so as to induce a magnetic field of greater than 1 Tesla in the magnetic media;
• g) holding the magnetic media at the target annealing temperature while maintaining the magnetic field and the vacuum in the chamber;
• h) allowing the magnetic material of the magnetic media to assume desired a orientation;
• i) cooling the magnetic media to about ambient temperature to preserve the desired orientation of the magnetic material;
• j) ramping down and removing the magnetic field;
• k) ramping down the vacuum to gradually reintroduce atmosphere within the chamber;
• and
• l) unloading the magnetic media.