The fact that the motion of the atoms of helium-3 gas is so quick that
the spins cannot follow the change of direction of an inhomogeneous m
agnetic field adiabatically is an important spin relaxation mechanism.
The spin relaxation rates are calculated for a spherical sample situa
ted at the centre of a Helmholtz pair. The calculation is made for the
first two nonvanishing terms in the inhomogeneity, the fourth and six
th degree terms.