Threshold magnetic fields for long-lived modes in the spin dynamics in 3H2-B

The temperature dependence of the threshold vatues of the magnetic fields turned-off in WP-mode experiments is investigated.It is shown that the threehold values can be related to the properties of the attractor regimes of the magnetization relaxation in 3He-B in a turned-off field. The regames involving a partially switched off external field with subsequent magnetization relaxation in a residual field of the order of dipole field are atso considered. It is concluded that threshold values for turned-off fields may also exist in this case. The existence of threshold fields is ascribed to the instability and chaotic regimes in the spin dynamics of superfluid 3He-B. The form of the order parameter for the initial stage of spatially nonuniform relaxation in a threshold magnetic field is discussed