An alpha particle with a charge of 2e (e = 1.6x10^-19 C) and a mass of 4me (me = 1.66x10^-27 kg) enters an area with a uniform magnetic field with a magnitude of 6.69 mT. The direction of the initial velocity of the particle is perpendicular to the direction of the magnetic field. The radius of curvature of the path of the alpha particle after entering the magnetic field is 2.24 cm. What is the magnitude of the velocity of the alpha particle?