Helmholz Coils

The z-axis magnetic field is supplied by Helmholz Coils. These consist of identical solenoids of radius R that are separated by R. These produce a reasonably uniform magnetic field while allowing access for the ESR probe. The magnetic field strength as a function of the input current is given by the expression

$$B=\frac{8N\mu _{0}I}{5^{\frac{3}{2}}R}$$ (7)

The ESR apparatus supplies the current for the coils. The ammeter is needed to measure the applied current. Do not allow the current to exceed the value specified in the ESR manual. Currents in excess of this value can damage the unit.
 

1999-09-14