Spontaneous hole-clump pair creation

Numerical simulations and quantitative theoretical explanations are present ed for the spontaneous formation of a hole-clump pair in phase space. The e quilibrium is close to the linear threshold for instability and the destabi lizing resonant kinetic drive is nearly balanced by either extrinsic dissip ation or a second stabilizing resonant kinetic component. The hole and clum p, each support a nonlinear wave where the trapping frequency of the partic les is comparable to the kinetic linear growth rate from the destabilizing species alone. The power dissipated is balanced by energy extracted by trap ped particles locked to the changing wave-phase velocities. With extrinsic dissipation, phase space structures always form just above the linear insta bility threshold. With a stabilizing kinetic component, an electrostatic in teraction is considered with varying mass ratios of the stabilizing and des tabilizing species together with collisional effects. With these input para meters, various nonlinear responses arise, only some of which sweep in freq uency. (C) 1999 American Institute of Physics. [S1070-664X(99)02608-7].