5469123 Ferromagnetic room shielding for the superconducting high field magnet of an NMR spectrometer

Abstract

In a magnetic shielding for a superconducting magnetic coil (2) arranged on the inside of a cryostat (1) and having a vertical axis for the production of a static magnetic field with a homogeneity of <10 -7 in an investigational volume (V) of a nuclear magnetic resonance (NMR) spectrometer, the shielding is a room shielding located at a separation from the cryostat (1), which includes at least two ferromagnetic, horizontally arranged plates (3, 4) of which one is arranged below and other above the cryostat (1), whereby the separation of the upper plate (3) from the center of the investigational volume (V) is approximately 1.5 to 3 times, preferentially approximately twice, as large as the separation (h) of the lower plate (4) from the center of the investigational volume (V), and vertical ferromagnetic side elements (5) are provided for which magnetically connect the upper plate (3) and the lower plate (4) and the upper plate (3) contains 1.5 times to 3 times, preferentially twice as much ferromagnetic material as the lower plate (4 ). In this fashion the magnetic field homogeneity is maintained and no significant forces occur during operation of the magnetic coil (2).