Large Magnetic Shielding Research Articles

Investigation of Electromagnetic Characteristic in Series-Connected Augmented Quadrupole Rail Launcher

The weight of projectiles and magnetic shield are two important factors influencing an electromagnetic launch (EML). The quadrupole rail launcher forms a cylindrical area in the middle of a launcher with very small magnetic field intensity, which can shield electromagnetic radiation and protect precision electronic components inside a projectile. However, the offset magnetic field weakens the electromagnetic thrust and decreases the launch efficiency. To solve the mentioned problem, the structure of a series-connected augmented quadrupole rail launcher is presented, the electromagnetic model based on the numerical analysis and the finite element method for nonaugmented and augmented quadrupole rail launcher is built. In addition, the distribution characteristic of current density, magnetic field intensity, and electromagnetic force of the two launchers is analyzed, respectively. The simulation results show that the current density distribution of rail in the nonaugmented launcher is O-like shape and the augmented launcher is C-like shape. Under given conditions, the electromagnetic thrust of the augmented launcher is larger about 3.7 times than that of the nonaugmented launcher. Meanwhile, a large magnetic shielding area can be kept in the augmented launcher.

Large magnetic shielding factor measured by nonlinear magneto-optical rotation

A passive magnetic shield was designed and constructed for magnetometer tests for the future neutron electric dipole moment experiment at TRIUMF. The axial shielding factor of the cylindrical magnetic shield was measured using a magnetometer based on non-linear magneto-optical rotation of the plane of polarized laser light upon passage through a paraffin-coated vapor cell containing natural Rb at room temperature. The laser was tuned to the Rb D1 line, near the 85Rb F=2→2,3 transition. The shielding factor was measured by applying an axial field externally and measuring the magnetic field internally using the magnetometer. The axial shielding factor was determined to be (1.3±0.1)×107, from an applied axial field of 1.45μT in the background of Earth׳s magnetic field.

DFT Study on the NMR Chemical Shifts of Molecules Confined in Carbon Nanotubes

Large magnetic shielding has been experimentally observed on certain organic molecules, regardless of their intrinsically different chemical natures, when they are confined within the carbon nanotubes. We investigated the underlying physics of the shielding effect by employing a series of density functional theory calculations on various molecule-confined-in-CNT systems. Particularly, the effects of the intermolecular interaction and the ring current of the CNTs on the chemical shifts of the confined molecules were investigated in detail. The results reveal that the changes in chemical shift mainly originate from the magnetic shielding induced by the delocalized π electrons. Electronic structure analysis for nonbonded interactions of host–guest and guest–guest indicated that this intermolecular interaction effect on chemical shift is significant for the polarizable molecules. Thus, the NMR responses of the molecules confined in CNTs are different from those of the molecules in other confining environments. Our study thus suggested that the chemical shift can be used as a probe to distinguish the molecules inside and outside of the CNT channels, as well as the type of CNTs (such as metallic and semiconducting).

Helmet-size vessels of high-Tcoxide superconductor for magnetic shield

Abstract We have developed a very large magnetic shielding vessel made from high-Tc Bi-Pb-Sr-Ca-Cu-O superconductor and have experimentally confirmed that this vessel can reduce a weak magnetic field to -100 dB or 1/105. The size of this vessel is 32 cm in diameter, 64 cm in depth and 2.5 cm in thickness. The shielding effect of the vessel does not decrease even at a low frequency like 0.2 Hz. The high attenuation ratio in the low frequency range indicates that magnetic shielding using a high-Tc superconductor is promising for neuromagnetic measurements with SQUID.

Large magnetic shielding vessels of high-Tc oxide superconductor and squid measurements

We have developed a very large magnetic shielding vessel of high-Tc BiPbSrCaCuO superconductor and experimentally confirmed that this vessel can reduce a weak magnetic field to −100 dB or 1 10 5 . The size of this vessel is 32 cm in diameter, 64 cm in depth and 2.5 cm in thickness. The shielding effect of the vessel does not go down even at such a low frequency as 0.2 Hz. The high attenuation radio in the very low frequency range indicates that magnetic shielding of high-Tc superconductor is promising for neuromagnetic measurements with SQUIDs.