L波段三维ESR成像系统的研制(Ⅰ)——L波段ESR成像的磁场及三维梯度磁场系统

研究并实现了L波段电子自旋共振三维成像（3D-EPRI）专用的三维梯度磁场系统，主磁场及扫描磁场系统以及相应的驱动控制系统. 梯度场线圈采用在铜板上用电切割方法加工的 平板式线圈，避免了用铜导线绕制线圈体积较大的缺点，从而缩小了主磁场的体积和极间距 . 梯度场强度在三维方向上均达到200 mT/m，驱动电流为20 A. 三维空 间线性度均优于5％；线性区域大于直径42 mm的球形空间. 两磁极间距离为63 mm，可以容纳通常体积的L波段谐振腔. 主磁场和扫描场线圈固定在同一轭铁架上. 它们可分别产生1.6～ 96 mT和0.2～16 mT的线性变化磁场. 5组磁场线圈（包括主磁场， 扫描磁场和三维梯度磁场）分别由5台独立的恒流驱动电源控制驱动. 电源通过数据接口由计算机控制. 初步成像实 验证明本工作所建立的磁场和梯度磁场系统可以用于EPRI实验.

L-BAND THREE DIMENSIONAL ESR IMAGING SYSTEM (Ⅰ) --Magnet and Magnetic Gradients for L-band 3D-ESRI

Main magnet, scan magnet and magnetic gradient coils used for L-band t hree dimensional electron paramagnetic resonance imaging were developed. Insteadof using the conventional copper wire design to wind the gradient coils, they w ere built using a whole copper plate with the electrical line cut technique. The new design remarkably reduced the volume of the gradient coils, and made the ma in magnet more effective. The maximum gradient strengths in all three directions reached more than 200 mT/m with a driving current of 20 A. The spatial linearit y of the gradients in all three directions was better than 5 %, and the linear ran g e was larger than a sphere of 42 mm in diameter. The distance between the surfac e s of the gradient coils was 63 mm, which was large enough to contain any type of L-band EPR cavity. The main magnet and the scan magnet coils were fixed on an iron frame. The magnet fields generated by the two magnets were 1.6～96 mT (main mag net) and 0.2～16 mT (scan magnet), respectively. All five magnet coils (main, sc an and three gradients) were driven with five independent instant current power su pplies, which were controlled by a computer through a data interface. The prelim inary imaging test showed that the magnets are practical for 3D-EPRI applicatio ns.