| 摘要 |
<p>Low-temperature (cryogenic) radio-frequency (RF) coils for nuclear magnetic resonance (NMR) applications include composite multi-layered structures including an internal normal metal layer clad on both sides by external high-purity annealed aluminum layers. The magnetic susceptibilities of the internal and external layers (46; 48a, 48b) are opposite in sign, and the thicknesses of the layers are chosen such that the composite structure has a net magnetic susceptibility equal to that of its surroundings (vacuum or support material). The internal layer (46) can have a higher resistivity and magnetoresistance than the external layers (48a, 48b). The use of high-purity, annealed aluminum for the external layers (48a, 48b) allows relatively high Q-factors for the cryogenic coils. <IMAGE></p> |
