The Influence of Plasma Induced by $\alpha $ -Particles on the Radar Echoes

At the different radioactivity, temperature, pressure, heights, and incident angles, the influences of the electromagnetic wave propagating in the α-decay radionuclide layer (RNL) coated on a perfect electric conductor system were simulated by the finite-difference time-domain method. The maximum electron density ionized by 5.45-MeV α-particles is ~1.8 × 10
¹¹
per cubic centimeter when the radioactivity is 10 Ci/cm
²
. The decrease of the reflectivity at altitude is much better than at ground and the decreasing amplitudes could reach 1-20 dB in the frequency range from 300 MHz to 40 GHz at an altitude of 10000 m. In addition, the same RNL would significantly reduce the back scattering bistatic radar cross section (RCS) of the platform. The decrease of RCS along the direction of the originally strongest reflection wave is nearly 25.5 dB when the incident angle is 60°.