Katsumi Kose1, Tomoyuki Haishi2
1Institute of Applied Physics,
Temperature
drift of the magnetic field of a thermally insulated yokeless permanent
magnet (field strength = 1.04 T) was measured for about 68 hours. The
temperature coefficient of the magnetic field was about -950 ppm/deg. The
largest Larmor frequency change was about 50 Hz/min. The performance of the
thermal insulation was evaluated with high resolution imaging (20~40 micron
square) of several samples. The results have suggested that careful choice of
the NMR lock interval and the pixel bandwidth will solve the temperature
drift problem of the high field yokeless magnet.