The long-term stability of an atomic magnetic resonance standard system for the reproduction of direct current and magnetic flux density

At the D. I. Mendeleyev Institute for Metrology (VNIIM), a standard system using /sup 4/He atomic magnetic resonance, has been operating for the past 10 years in a long-term investigation into the reproducibility of low magnetic flux densities and direct currents. Research into the base elements of this system over the past five years has shown that the instability of the coil constant of a standard solenoid coil, and the nonlinearity of the frequency-to-current conversion coefficient of a quantum system for current reproducibility in the current range 0.1 to 1 A, are less than 1 part in 10^7.