Blob Method for Kinetic Plasma Simulation with Variable-Size Particles

A new approach to particle in cell simulation is presented for collisionless plasmas. The new method is based on computational particles of variable size (blobs). Each blob represents an element of phase space and its shape and size are evolved in time to represent better the correct evolution. The blob particles can be split to increase the accuracy in selected regions of stronger gradients. Blobs can also be coalesced to keep the total number of blobs constant. The performance of the blob method is analyzed in the case of the Landau damping and in the formation of a sheath in a bounded plasma. The results show the correctness and effectiveness of the new method. When compared to standard PIC methods, the blob technique reduces the noise for a given number of computational particles.