On the Helicity of Radiative Electromagnetic Fields

We derive relativistically invariant expressions for the magnetic and electric helicities of free electromagnetic field through currents, which created those field. demonstrate that, radiative fields (e.g., laser pulses), both are conserved equal to each other. Moreover, conservation helicity means in fields, vectors always orthogonal Proceeding quantum theory, we show that corresponding operator is sum projections spins all photons onto their momenta. Finally, as an example, obtain discuss total helicity, number photons, spin momentum a dipole pulse.