Thermal Specimen Demagnetizers

ASC's Model TD48 Thermal Demagnetizer features a large internal diameter oven and three-row sample boat for heating up to 48 one-inch diameter or one-inch cubic geologic samples in a single batch. The oven and adjacent fan-assisted cooling zone are housed in a three layer seamless magnetic shield which permits cooling of one batch while a second batch is heating. The cooling chamber has two additional shields which limit the maximum internal field to less than 10 gammas with the instrument oriented perpendicular to the earth's field. The oven has three independently controlled zones - a large sample zone and two small trimmer end zones - which minimize temperature gradients across the sample zone while keeping overall oven length to a minimum. The system was designed for long service life by incorporating features into the oven and sample boat that protect the internal oven wall from damage.

Controlled Field Coil

An optional controlled field coil encompassing the entire oven and cooling section is available. The coil is wound on a non-magnetic form fitted just inside the inner of the three full length shields. This coil will produce an axial field of approximately 1 Gauss per ampere of applied current with a maximum field of 10 Gauss. The power supply for the coil is not included. ASC can provide a power supply for an additional cost. Please contact our East Coast office at (800) 875-4272 or (401) 423-3537 for assistance in selecting a power supply which is best suited for your application.

ASC Model TD48-SC
High-capacity single-chamber thermal specimen demagnetizer

The TD48-SC thermal demagnetizer has a single chamber in which the samples are heated and cooled. The oven chamber is enclosed in a three layer, cylindrical mu metal shield which will attenuate the earth's field down to less than 10 nT when the system is oriented in an east-west position. Up to 48 samples can be processed in a single batch. The oven has three separate heating zones - a long central sample zone and a short trimmer zone on each end of the central zone. The three heating zones are individually monitored and driven by separate temperature programmers which are all tied to a single setpoint temperature. This three-zone design insures that temperature gradients over the length of the sample zone are kept to a minimum. The end zones and the floor of the central zone are lined with a quartz sleeve. This feature minimizes wear to the oven wall but still allows for excellent feedback between the sample zone thermocouple mounted on the sample boat and the heater windings.

The temperature controllers are microprocessor based PID type controllers which are tuned to minimize temperature overshoot during heating and maximize temperature stability at the setpoint. A timer feature allows the user to start a batch of samples and complete the heating and cooling cycles without attending the unit. Heating and cooling times for 48 samples to a temperature of 600 degree C are 45 minutes and 20 minutes, respectively.

Optional features include:
Field Coil for applying a magnetic field in the oven.
Controlled Atmosphere Chamber for either evacuating or introducing a flow of inert gas to surround the samples