Abstract:

Main magnet, scan magnet and magnetic gradient coils used for L-band t hree dimensional electron paramagnetic resonance imaging were developed. Instead of 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.

Key words: ESR, ESRI, gradient magnetic field, magnet, L-band