Nuclear magnetic resonance sensor for measuring water content in wood

Abstract

The invention discloses a nuclear magnetic resonance (NMR) sensor for measuring water content in wood. The NMR sensor includes a radio frequency coil, a magnet structure and a matched circuit. The matched circuit supplies an excitation current to the radio frequency coil which generates a radio frequency magnetic field and detects an echo signal generated in a to-be-tested sample. The radio frequency magnetic field is orthogonal with a static magnetic field generated in the magnet structure. The magnet structure includes a left magnet structure and a right magnet structure which are disposed oppositely. The radio frequency coil includes a left radio frequency coil between the to-be-tested sample and the left magnet structure and a right radio frequency coil between the to-be-tested sample and the right magnet structure. The left radio frequency coil is connected to the right radio frequency coil in series. A uniform zone of the static magnetic field generated in the NMR sensor is located in the center of the magnet structure, so that the to-be-tested sample can be detected just by putting the to-be-tested sample in the magnet structure without tree felling. The sensor is arranged on the periphery of a tree to perform undamaged NMR detection.

Description

technical field [0001] The invention relates to a sensor for detecting moisture, in particular to a nuclear magnetic resonance sensor for measuring moisture content in wood. Background technique [0002] The dry humidity of a tree mainly depends on its water content. When a living tree grows, its roots continuously absorb water from the soil, and the water is sent to various organs of the tree by the trunk tissue, and at the same time photosynthesize the leaves. The nutrients produced are transported by the phloem of the trunk to all parts of the tree. Moisture is an essential substance for tree growth, and moisture in wood is an important content for testing wood physiological indicators. It can be seen that it is very necessary to study the law of water migration in wood. At present, there are three methods for the determination of moisture in wood: drying method, distillation method and conductive method. [0003] The drying method, also known as the gravimetric method...

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Problems solved by technology

Although this method does not need to destroy the sample wood and make a moisture content sample, it cannot measure the specific flow direction of the moisture in the wood, nor can it judge the migration law of the moisture in the wood.

[0006] It can be seen that among the above three measurement methods for measuring the moisture content in wood, the drying method and the distillation method cannot achieve non-destructive measurement, and must destroy the sample wood, and the conductivity method cannot measure the specific flow direction of the moisture in the wood.

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