物理实验
物理實驗
물리실험
PHYSICS EXPERIMENTATION
2015年
1期
1-4
,共4页
核磁共振%扫场%感生电动势
覈磁共振%掃場%感生電動勢
핵자공진%소장%감생전동세
nuclear magnetic resonance%modulation magnetic field%induced electromotive force
在连续波核磁共振实验中,通常采用低频扫场产生重复再现的共振吸收信号。当处于磁场中的射频线圈引线回路等效面积不为零时,简谐扫场必然引起该闭合回路的磁通量变化,由此而产生同频简谐感生电动势并与核磁共振信号叠加共同构成振荡器输出信号。由于扫场上升和下降过程的感生电动势方向相反,从而扫场前半周和后半周所对应的共振吸收测量信号存在差异。实验结果表明:扫场强度及方向对核磁共振测量影响来源于实验测量技术缺陷,而非核磁共振的物理本质。
在連續波覈磁共振實驗中,通常採用低頻掃場產生重複再現的共振吸收信號。噹處于磁場中的射頻線圈引線迴路等效麵積不為零時,簡諧掃場必然引起該閉閤迴路的磁通量變化,由此而產生同頻簡諧感生電動勢併與覈磁共振信號疊加共同構成振盪器輸齣信號。由于掃場上升和下降過程的感生電動勢方嚮相反,從而掃場前半週和後半週所對應的共振吸收測量信號存在差異。實驗結果錶明:掃場彊度及方嚮對覈磁共振測量影響來源于實驗測量技術缺陷,而非覈磁共振的物理本質。
재련속파핵자공진실험중,통상채용저빈소장산생중복재현적공진흡수신호。당처우자장중적사빈선권인선회로등효면적불위령시,간해소장필연인기해폐합회로적자통량변화,유차이산생동빈간해감생전동세병여핵자공진신호첩가공동구성진탕기수출신호。유우소장상승화하강과정적감생전동세방향상반,종이소장전반주화후반주소대응적공진흡수측량신호존재차이。실험결과표명:소장강도급방향대핵자공진측량영향래원우실험측량기술결함,이비핵자공진적물리본질。
The resonance absorption was generated using a magnet with the low‐frequency modu‐lation field in the continuous wave nuclear magnetic resonance experiment .When the loop area vertical to magnet was not zero , the flux in the closed loop caused by the modulation magnetic field was changed ,then the induced electromotive force would be added to the nuclear magnetic resonance sig‐nal .Because the rising and falling of the modulation field induced opposite electromotive forces ,the resonance absorption signals for the first and second half period of the modulation field were different . The experiment showed that the reason for the influence from magnitude and orientation of modula‐tion field was not attributed to its physics but the defect of measurement technique .