Browse Prior Art Database

Variable Inductance Pick-Up Coil for Detection of Flux Trapped in a Loop

IP.com Disclosure Number: IPCOM000042738D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Tesche, CD: AUTHOR

Abstract

This article relates generally to the detection and measurement of magnetic fields and more particularly to the detection and measurement of magnetic fields using a variable inductance pick-up coil for the detection by a SQUID (Superconducting Quantum Interference Device) of flux trapped in a loop. Still more specifically, apparatus is provided which permits the detection of magnetic field passing through a loop and the readout by a SQUID magnetometer of flux trapped in a loop to be separated into two separate steps. SQUIDS are extremely sensitive detectors of changes in the flux passing through the SQUID loop. As shown in the above figure, a SQUID 1 having a loop L is typically inductively coupled to an input coil Li and a pick-up coil Lp connected in series. Optimal resolution occurs if LpZLi .

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 59% of the total text.

Page 1 of 2

Variable Inductance Pick-Up Coil for Detection of Flux Trapped in a Loop

This article relates generally to the detection and measurement of magnetic fields and more particularly to the detection and measurement of magnetic fields using a variable inductance pick-up coil for the detection by a SQUID (Superconducting Quantum Interference Device) of flux trapped in a loop. Still more specifically, apparatus is provided which permits the detection of magnetic field passing through a loop and the readout by a SQUID magnetometer of flux trapped in a loop to be separated into two separate steps. SQUIDS are extremely sensitive detectors of changes in the flux passing through the SQUID loop. As shown in the above figure, a SQUID 1 having a loop L is typically inductively coupled to an input coil Li and a pick-up coil Lp connected in series. Optimal resolution occurs if LpZLi . The inductance value of Li is limited by the requirement that good coupling be maintained between input coil Li and the SQUID loop L. Thus, the area of the pick-up coil Lp is limited by the small inductance of the SQUID loop (L~10pH-1nH). This limits the magnetic field resolution of the device, since the flux linked is d=BA, where A is the area of the loop. According to concept involved herein, the ground plane 2 under pick-up loop Lp, is constructed so that it may be in either the superconducting or normal state and has a hole 3 formed in it of area a. When ground plane 2 is in the normal state, fl...