On Trapped-Particle Effect on Shielding in Collisionless Plasmas

The contribution of charged particles moving on finite orbits near a charged spherical body to shielding of the body is discussed. By means of a numerical experiment simulating the process of charging of an absorbing sphere in plasma, it is shown that the net charge of the trapped-particle cloud arising around the sphere can reach very high values. The shielding under these conditions becomes strongly nonlinear in contrast to Debye shielding.