Base on certain main magnets of nmr this thesis designs the most excellent structure of the pole shape and obtains a relatively uniform magnetic field in a large imaging volume . the calculating model of pole shape made of pure iron can be simplified with the infinite permeability and calculated with the scalar potential . the rule between pole shape and the homogeneity or the size of uniform region of magnetic field is discovered and factors of influencing the homogeneity of the magnetic field are held so that the main magnet with the optimized size of pole shape can produce a relatively uniform magnetic field in a large imaging volume 本文針對一類典型結(jié)構(gòu)的主磁體,通過磁場分析與大量的計算,找到了極靴形狀的改變影響樣品區(qū)磁場均勻度以及均勻區(qū)域范圍的規(guī)律,掌握了極靴形狀的變化趨勢及其形狀影響樣品區(qū)磁場均勻度的各種因素,進(jìn)行了極靴的形狀優(yōu)化設(shè)計并編制了相應(yīng)的計算機(jī)軟件,給出了極靴形狀的具體尺寸,使得主磁體能在更大空間內(nèi)產(chǎn)生相對均勻的磁場。
Secondly , some recently research results and some unsolved problems about the magnetic vector potential a , electric scalar potential and magnetic scalar potential of the transient eddy current formulation are deeply analyzed in the paper and the magnetic vector potential a is chosen to calculate the specified physical model discussed in this paper 其次,概括地分析了國內(nèi)外對向量磁位( ? ) 、標(biāo)量電位、標(biāo)量磁位的研究現(xiàn)狀及存在的問題,在此基礎(chǔ)上,確定用向量磁位( ? )來計算永磁操動機(jī)構(gòu)的物理模型,并證明在二維非線性情況下,庫侖規(guī)范自然滿足。