The Research Of Curcuit Portion Of Small NMR System

This text introduce the theory of nuclear magnetic resonance(NMR) and the design of a NMR system. Nuclear magnetic resonance is a subject which studies the phenomenon of resonance absorption when nucleus was placed in the stationary magnetic field and act with applied high frequency fields. It's a technology that uses the energy change of magnetic field to detect some useful information of the nucleus. During the last 50-year, it makes an incredible progress in the field of studying the microstructure of some matters with nuclear magnetic resonance. From the late 70^th, with the developing of computer science and principle of NMR, it has been an indispensable experimental method which needed by physics chemistry biology medical science and geology. In the NMR system, the RF pulse is generated by the signal source, it is exemplified by power amplifier. And then it is sent to the NMR probe, the NMR probe also is the signal receive apparatus, the received signal is the sample signal which is modulated by the RF signal. The signal which is received by the probe is a small signal, it may be exemplified by the amplifier, and then it may be processed and get the sample signal. The circuit theory which is introduced by the text includes three portions:( 1 ) The design and modify of the power amplifier.( 2 ) The design of NMR probe.( 3 ) The design of pre-amplifier.Moreover, some weak points and the aspects of needing improvements are bring forward.