To improve the interruption performance of a vacuum circuit breaker

a asymmetric dual-coil bipolar contact with axial magnetic field（AMF） is designed for vacuum arcing chamber. A 3-D model of the contact structure is established

and the finite element method is employed to conduct 3-D magnetic field simulation of the contact system under consideration of eddy current effect. The results show that when the current gets its peak value

the effective area of AMF strength

generated on the moving and stationary contact surfaces as well as on the central plane of contact gap

is larger and uniform

the maximum AMF strength on the stationary and moving contacts is up to 0.842 T and 0.306 T

respectively. When the current passes zero point

the residual magnetic field on the central plane of contact gap is small

the maximum hysteresis lag is about 0.87 ms

and the conductor resistance is 29.77 μΩ. This new-type asymmetric contact has larger AMF strength

smaller residual magnetic field strength and shorter hysteresis lag at current passing zero moment

which facilitates the interruption performance of the circuit breaker.