STEADY-STATE FORMATION OF A TOROIDAL ELECTRON CLOUD

A novel scheme of injection and confinement of electrons is reported for the formation of a toroidal electron cloud in the presence of a static toroidal magnetic field. The scheme is based on the use of a combination of externally applied electric field and the self-consistent space charge field for the electron trapping and confinement. The time development of electron cloud potentials measured in the poloidal plane of the torus is presented. A potential well depth exceeding the initial kinetic energy of the electrons is observed, indicating collective effects. The effect of external field on the total charge and capacitance of the electron cloud is also presented.