GB2265013A - Coil system for vibrating sample magnetometer - Google Patents

Abstract

A coil system used as the pickup in a vibrating sample magnetometer comprises printed patterns of conductors on an insulating material. The pickup coils thus occupy minimum space within the magnet. A typical pattern is as shown. <IMAGE>

Description

coil system of the VSM The vibrating sample magnetometer ( VSM) is used to measure the magnetic characteristics of magnetic samples. These can be natural materials or man made. In the latter category are magnetic tapes, magnetic disks magnetic stripes or printing on credit cards and the like. The parameters usually found by the instrument are magnetic saturation, magnetic susceptibility at various field values, remanence, and coercive force.

To make this measurement three essential things are needed.

1) A magnetic field that can be varied to at least 1 Tesla.

2) A system for vibrating the sample within this field.

3) A coil system that is sensitive to the induced magnetism'of the sample.

rhere are well known methods of doing these things, but the present application refers to the coil system. It is a fact that high magnetic fields covering large volumes are difficult to obtain. The larger the volume the greater size of the magnet and the greater is the power required. Current coil systems comprising many turns of thin wire iinevitable take up considerable space, this space is essentially wasted and so a bigger magnet than is necessary to encompass the sample is needed. This adds greatly to the cost since the nature of magnetic fields means that even a small increase in field volume means a considerable increase in magnet size and power requirements.

The new coil system.

Printed circuits consist of a layer of copper on an insulating board.

In the simplest form the copper layer is on one side, but boards with copper on both sides are common. Boards can also be built up containing many layer of copper alternating with layers of insulating materials. Any pattern of conductors can be made by putting the pattern on to the board by photographic means and then etching away all the copper except the required pattern. In the present invention the pattern takes the form of a coil system.

Printed circuit coils are well known but the invention refers specifically to the use of a coil system as the pickup coil of a VSM.

There are many possible forms, in the preferred system a double sided printed circuit is used with the pattern on both sides of the board.

Although round coils are usually used the printed circuit technique allows the use of a rectangular form which has the additional advantage of being a more efficient detector.

Single turn coils are the minimum form but multiturn forms are preferred. An important feature of the system is the use of plated through holes to connect the various parts of the coils system together. These are important since they add essentially no additional thickness to the system and therefore permit the minimum field size to be used.

A typical pattern is shown in fig 1.

Claims (9)

Claims.

1) A printed circuit is used to make the pickup coils for a Vibrating sample magnetometer.

2) The coils can be either single turn or multi turn.

3) The coils can be either on a single sided board or on both sides of a double sided board.

4) The coils (either single turn or multiturn) can be of many thin layers stacked together to make a multilayered sandwich.

5) The various parts of the coil system are connected together by plated through holes.

6) The various parts of the coil can be connected together by plated through holes.

7) The boards can be of the flexible form of printed circuit material.

8) The flexible sheets can be bonded together to make a multilayered coil.

9) The pattern can be of any form suitable to detect the field from the sample.