  Magnetic resonance of sodium fluorescence is studied with varying laser
intensity, duty cycle, and field strength. A magnetometer based on sodium vapor
cell filled with He buffer gas is demonstrated, which uses a single
amplitude-modulated laser beam. With a 589 nm laser tuned at D1 or D2 line, the
magnetic field is inferred from the variation of fluorescence. A magnetic field
sensitivity of 150 pT per Hz square root is achieved at D1 line. The work is a
step towards sensitive remote magnetometry with mesospheric sodium.
