The effect of a vortical electric field on nonlinear pattes in excitable media is studied.When an appropriate vortex electric field is applied,the system exhibits patte transition from chemical turbulence to spiral waves,which possess the same chirality as the vortex electric field.The underlying mechanism of this is discussed.We also show the meandering behavior of a spiral under the taming of a vortex electric field.The results obtained here may contribute to control strategies of pattes on surface reaction.Spiral waves are one of the most common and widely studied pattes in nature.They appear in hydrodynamic systems,chemical reactions and a large variety of biological,chemical and physical systems.[1-5] Much attention has been paid to their rich nonlinear dynamics,as well as potential applications in various biological or physiological systems,since the emergence and instability of spirals usually lead to abnormal states,for example in cardiac arrythmia[6,7] and epilepsy[8].Much research has been carried out in studying patte formations in catalytic CO oxidation on Pt(110),[9-11] because they provide practical utilization in industry.A rich variety of spatiotemporal pattes,including travelling pulses,standing waves,target pattes,spiral waves and chemical turbulence have been observed in this system.[12-16]