Clouds-in-clouds, clouds-in-cells physics for many-body plasma simulation (Reprinted from the Journal of Computational Physics, vol 3, pg 494-511, 1969)

A clouds-interacting-with-clouds, clouds-in-cells method (CIC) is presented for many-body nonlinear plasma problems. Density and force are obtained by assuming that the particles have finite size, are tenuous, and may pass through one another; the particles are thus called clouds. They obey a Coulomb force (similar to 1/r or 1/r(3)) when separated and a linear force (similar to r) when overlapping, allowing simple harmonic oscillations at small separation. CIC is contrasted with the zero-size particle and nearest-grid-point approach, ZSP-NGP. CIC appears to have substantially less unwanted noise than ZSP-NGP and should be more useful in simulating dense plasmas, Initial runs have been encouraging. The methods may find use in other many-body simulations, such as with stars, or with particles in phase space. (C) 1969 Academic Press.