HE-3 NMR WITH A 100 MU-M PLANAR NB COIL

A superconducting 100 mu m planar coil has been tested for low field c w NMR. The nine-turn 5 nH coil is connected via a planar 1:8 step-up t ransformer to an external parallel capacitor and resonated at 0.8 MHz to give a Q of 350. The tank circuit voltage is measured with a liquid He temperature GaAs MESFET preamplifier. Test experiments have been c onducted by immersing the Si chip with the planar pick-up coil in liqu id and solid He-3 to measure their cw NMR absorptions in the temperatu re range 0.05 - 0.5 K.