Abstract
We report a new phenomenon named particlespout in which the particles spout in a specially designed microwave cavity. An ionic crystal of sodium chloride was heated in the microwave applicator. Beyond the melting point, the particles began to evaporate and move upward owing to thermal convection. These particles formed a funnel shape similar to a waterspout but they had two layers. In comparison with conventional heating, only a single but unstable columnar vortex can be observed. A theoretical model is proposed that attributes the observed phenomenon to the rotational kinematics together with the ponderomotive force. These two effects confine the particles to the inner and outer bounds, respectively.