CN210142181U - Nuclear magnetic resonance analysis probe with high signal-to-noise ratio and low dead time - Google Patents
Nuclear magnetic resonance analysis probe with high signal-to-noise ratio and low dead time Download PDFInfo
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- CN210142181U CN210142181U CN201920843433.1U CN201920843433U CN210142181U CN 210142181 U CN210142181 U CN 210142181U CN 201920843433 U CN201920843433 U CN 201920843433U CN 210142181 U CN210142181 U CN 210142181U
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Abstract
The utility model discloses a low dead time's of high SNR nuclear magnetic resonance analysis probe, its resonant circuit is connected its characterized in that with radio frequency receiving and dispatching duplexer in the magnet: it comprises parallel matching capacitor (1), radio frequency coil (2), series connection matching capacitor (3) and load capacitance (4), load capacitance (4) one end ground connection, load resistance (5) are inserted to one end, and both establish ties the back and are connected in parallel with series connection matching capacitor (3), radio frequency coil (2) one end connects series connection matching capacitor (3), and one end connects the signal end, one end of parallel matching capacitor (1) connects the signal end, and other end ground connection. The utility model discloses an adjustment load capacitance capacity value has improved probe SNR, has reduced probe dead time, provides technical condition for short relaxation components such as organic matter in the measurement shale, kerogen.
Description
Technical Field
The utility model relates to a circuit of tuning and matching nuclear magnetic resonance analysis probe, especially can increase SNR and reduce dead time's electric capacity tuning and matching circuit.
Background
Nuclear Magnetic Resonance (NMR) technology is widely studied and applied for its performance superiority, and a probe is one of the indispensable core components in a NMR spectrometer. The signal-to-noise ratio and the dead time are important indexes for measuring the performance of the probe, and the higher signal-to-noise ratio and the lower dead time are beneficial to the poorer signal of the detected sample.
The traditional nuclear magnetic resonance analysis probe at present has the technical defects of low signal-to-noise ratio and high dead time.
SUMMERY OF THE UTILITY MODEL
In order to overcome the technical insufficiency that current nuclear magnetic resonance analysis probe SNR is lower, dead time is higher, the utility model provides a tuning and matching circuit based on electric capacity, this circuit has improved the SNR of probe, and has reduced the dead time.
The utility model adopts the following technical scheme: the utility model discloses a low dead time's of high SNR nuclear magnetic resonance analysis probe, its resonant circuit is connected its characterized in that with radio frequency receiving and dispatching duplexer in the magnet: the load capacitor is grounded at one end and connected with a load resistor at one end, the load capacitor and the load resistor are connected in parallel after being connected in series, one end of the radio frequency coil is connected with the series matching capacitor, the other end of the radio frequency coil is connected with the signal end, and one end of the parallel matching capacitor is connected with the signal end while the other end of the parallel matching capacitor is grounded.
Further, the series matching capacitor is a frequency tuning capacitor, the resonant frequency of the radio frequency coil can be tuned to the resonant frequency corresponding to the field intensity of the magnet, and the parallel matching capacitor and the series matching capacitor match the impedance of the probe resonant circuit to a resistance of 50 ohms and a reactance of 0 ohms.
Further, the resonant frequency is known according to the field intensity of the used magnet, so that the resonant frequency of the tuned circuit is adjusted to the required frequency by adjusting the capacitance value of the frequency tuning capacitor.
Further, according to the lossless transmission line theory, when the terminal load impedance is equal to the characteristic impedance of the uniform transmission line, no reflected wave exists on the transmission line, only the incident wave of the voltage and the current which are transmitted from the signal source to the load, and the signal power excited by the signal source completely reaches the load end and is absorbed by the load.
Furthermore, the tuning and matching of the radio frequency coil is to adjust the resonance frequency of the coil to the resonance frequency corresponding to the magnetic field of the target area of the magnet structure, and to match the total impedance of the coil to the characteristic impedance of the transmission line, so that the coil obtains the maximum transmission energy; given the characteristic impedance of the nmr power amplifier system and coaxial cable is 50 ohms, the rf coil needs to be tuned and matched so that the nmr probe circuit impedance as viewed from the input is 50 ohms while ensuring that the frequency is the desired resonant frequency.
Compared with the prior art, the beneficial effects of the utility model are that:
the utility model discloses an adjustment load capacitance holds the value, has improved probe SNR, has reduced probe dead time, can carry out effective measurement to organic matter in the shale, short relaxation components such as kerogen.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Reference numbers in the figures:
1-parallel matching capacitor 2-radio frequency coil 3-series matching capacitor
4-load capacitance 5-load resistance.
Detailed Description
The following detailed description of the preferred embodiments of the present invention will be provided in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the protection scope of the present invention can be defined more clearly and clearly.
Referring to fig. 1, a nuclear magnetic resonance analysis probe with high signal-to-noise ratio and low dead time, a resonance circuit of which is connected with a radio frequency transceiving duplexer in a magnet, is composed of a parallel matching capacitor 1, a radio frequency coil 2, a series matching capacitor 3 and a load capacitor 4, one end of the load capacitor 4 is grounded, the other end is connected with a load resistor 5, the two are connected in series and then connected in parallel with the series capacitor 3, one end of the radio frequency coil 2 is connected with the series matching capacitor 3, the other end is connected with a signal end, one end of the parallel matching capacitor 1 is connected with the signal end, and the other end is; in order to facilitate tuning and matching to the resonant frequency, the series matching capacitor 3 is designed as a continuously tunable capacitor.
Specifically, the series matching capacitor 3 is a frequency tuning capacitor, and can tune the resonant frequency of the radio frequency coil 2 to the resonant frequency corresponding to the field intensity of the magnet, and the parallel matching capacitor 1 and the series matching capacitor 3 are both impedance matching capacitors, and can match the impedance of the probe resonant circuit to a resistance of 50 ohms and a reactance of 0 ohms.
Specifically, in the example shown in fig. 1, the load capacitance 4 is selected to be 100 picofarads based on a magnetic field of 10.02MHz at the target region of the magnet structure. According to the resonant frequency value, the resistance and inductance parameters of the radio frequency coil 2 and the load capacitance value, the capacitance values of the parallel matching capacitor 1 and the series matching capacitor 3 are 122 picofarads and 671 picofarads.
To sum up, the utility model discloses an adjustment load capacitance appearance value has improved probe SNR, has reduced probe dead time, can carry out effective measurement to short relaxation components such as organic matter in the shale, kerogen.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment, but all equivalent modifications or changes made by those skilled in the art according to the present invention should be included in the protection scope of the claims.
Claims (2)
1. The utility model provides a low dead time's of high SNR nuclear magnetic resonance analysis probe, its resonant circuit is connected with radio frequency receiving and dispatching duplexer in the magnet, its characterized in that: it comprises parallel matching capacitor (1), radio frequency coil (2), series connection matching capacitor (3) and load capacitance (4), load capacitance (4) one end ground connection, load resistance (5) are inserted to one end, and both establish ties the back and are connected in parallel with series connection matching capacitor (3), radio frequency coil (2) one end connects series connection matching capacitor (3), and one end connects the signal end, one end of parallel matching capacitor (1) connects the signal end, and other end ground connection.
2. A high signal-to-noise ratio low dead time nmr analysis probe according to claim 1, wherein: the series matching capacitor (3) is a frequency tuning capacitor, the resonance frequency of the radio frequency coil (2) can be tuned to the resonance frequency corresponding to the field intensity of the magnet, and the parallel matching capacitor (1) and the series matching capacitor (3) match the impedance of the probe resonance circuit to the condition that the resistance is 50 ohms and the reactance is 0 ohms.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920843433.1U CN210142181U (en) | 2019-06-05 | 2019-06-05 | Nuclear magnetic resonance analysis probe with high signal-to-noise ratio and low dead time |
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| CN201920843433.1U CN210142181U (en) | 2019-06-05 | 2019-06-05 | Nuclear magnetic resonance analysis probe with high signal-to-noise ratio and low dead time |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112147554A (en) * | 2020-09-05 | 2020-12-29 | 武汉联影生命科学仪器有限公司 | Frequency matching and tuning device for receiving coil, cryogenic probe and magnetic resonance device |
| WO2023093082A1 (en) * | 2021-11-25 | 2023-06-01 | 浙江大学 | Component layout method and system based on radio-frequency emission surface coil, and coil |
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2019
- 2019-06-05 CN CN201920843433.1U patent/CN210142181U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112147554A (en) * | 2020-09-05 | 2020-12-29 | 武汉联影生命科学仪器有限公司 | Frequency matching and tuning device for receiving coil, cryogenic probe and magnetic resonance device |
| CN112147554B (en) * | 2020-09-05 | 2023-08-15 | 武汉联影生命科学仪器有限公司 | Frequency and matching tuning device of receiving coil, low-temperature probe and magnetic resonance device |
| WO2023093082A1 (en) * | 2021-11-25 | 2023-06-01 | 浙江大学 | Component layout method and system based on radio-frequency emission surface coil, and coil |
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