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Flux Quanta Counting Magnetometer Using a Thin Walled Superconducting Ring

IP.com Disclosure Number: IPCOM000045547D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

McLachlan, DS: AUTHOR

Abstract

The phase diagram of H inside vs. H outside for a thin-walled superconducting ring will almost certainly be similar to that of a hollow cylinder, which is shown in Fig. 1. The envelope 10 of the phase diagram includes position of voltage spike 11 and equilibrium flux or field contour 12. The device, shown in Fig. 2, consists of a planar superconducting ring 20 to which two current leads 21 and 22 are attached. Two further leads 23 and 24, which lead to a device 26 which can detect and count voltage spikes, are attached to leads 21 and 22, respectively.

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Flux Quanta Counting Magnetometer Using a Thin Walled Superconducting Ring

The phase diagram of H inside vs. H outside for a thin-walled superconducting ring will almost certainly be similar to that of a hollow cylinder, which is shown in Fig. 1. The envelope 10 of the phase diagram includes position of voltage spike 11 and equilibrium flux or field contour 12. The device, shown in Fig. 2, consists of a planar superconducting ring 20 to which two current leads 21 and 22 are attached. Two further leads 23 and 24, which lead to a device 26 which can detect and count voltage spikes, are attached to leads 21 and 22, respectively.

As the current in the input coil 25 increases (or decreases), the phase diagram shown in Fig. 1 is swept through. Every time a point is reached where the flux quanta changes, a voltage spike is generated and counted. When used as a magnetometer, input coil 25 is the secondary of a flux transformer. The device can also be used as a digital voltmeter or ammeter.

Although similar to a SQUID flux-counting magnetometer, this device is based on a different physical phenomenon and should have different basic limitations.

Remarks 1) The current i(o) passign through lines 21 and 22, which is kept low, produces no net flux. 2) The wall should be fabricated out of a very high resistivity (possibly amorphous) superconductor. This will result in a

large penetration depth, making the thin walled

condition (t less or equal to L

ambda) easier

to attain. The...