Magnetic resonance emission device and control method based on wide matching and short dead zone
A technology of transmitting device and magnetic resonance, applied in the direction of electronic magnetic resonance/nuclear magnetic resonance detection, etc., can solve the problems of low signal amplitude, influence detection effect, difficulty in data processing and inversion, etc., so as to improve signal amplitude and reduce dead rate. zone time, the effect of improving the detection effect
Active Publication Date: 2021-08-17
JILIN UNIV
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[0005] The technical problem to be solved by the present invention is to provide a short dead zone magnetic resonance emission device and control method based on wide matching, to solve the problem that the amplitude of the signal itself is low, and it is almost completely submerged in the noise after energy release time attenuation. Processing and inversion bring great difficulties and seriously affect the detection effect
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[0074] Now according to the actual detection, it is determined that the equivalent parameters of the coil are L=0.8mH, R=1Ω, and 10 diodes with a clamping voltage of 100V are selected in series, and the maximum clamping voltage is 1000V. If the current drops to 0.2%, it is turned off. The target The dead time is 1ms, and the specific implementation steps of the actual detection are as follows:
[0075] a. Parameter setting: PC upper computer 1 transmits emission parameters and control signals to the main control module 2, including: excitation current I=50A, excitation voltage U=290V, excitation frequency f=2330Hz, preset excitation time t=40ms, excitation Pulse duty ratio d=45%, superposition times k=8;
[0076] b. Clamping voltage adjustment: the main control module determines the clamping voltage value according to the excitation current, excitation voltage and target dead time, and determines the number of clamping diodes connected to the loop according to the clamping vol...
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The invention relates to the field of geophysical exploration equipment, in particular, to a short dead zone magnetic resonance transmitting device and a control method based on wide harmonic distribution, a PC host computer, and a main control module, which control DC-DC according to the instructions of the host computer The converter charges the energy storage capacitor, and the charging energy source is the battery; the H-bridge transmitting module and the coil are controlled to transmit bipolar pulses by sending PWM waves, and the transmitting energy source is the energy storage capacitor; The on-off of a switch is controlled by controlling the second switch driving module to control the on-off of the second switch, and the third switch driving module is controlled to control the clamping voltage of the clamping module; The switch control signal is negated to complement the turn-on signals of the first switch and the second switch. It solves the problem that the signal itself has a low amplitude and is almost completely submerged in noise after being attenuated by the release time, which brings great difficulties to subsequent data processing and inversion, and seriously affects the detection effect. It can effectively shorten the shutdown time of the transmitting system. Reduce the dead time of magnetic resonance detection, thereby increasing the signal amplitude.
Description
technical field [0001] The invention relates to the field of geophysical exploration equipment, in particular to a wide-matching-based short-dead zone magnetic resonance transmitting device and a control method. Background technique [0002] Ground magnetic resonance technology (Magnetic Resonance Sounding, MRS) is currently the only geophysical method for non-invasive groundwater detection, and is widely used in groundwater detection. When the magnetic resonance water detection system detects groundwater, the transmitter first transmits a bipolar pulse for a certain period of time through the load coil to excite the hydrogen protons in the groundwater, and then removes the excitation pulse, and the receiver receives the induced free induction through the same coil. Attenuation (Free Induction Decay, FID) signal, so as to invert the hydrogeological situation. [0003] The effective signal of MRS is nV level, so the receiving system meets the characteristics of weak signal a...
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IPC IPC(8): G01V3/14
CPCG01V3/14
Inventor 林婷婷李苏杭张洋万玲滕飞
Owner JILIN UNIV