Motion of charqec1 part.icles in magnetic and/or electricrnfields (from simple to cOInnlex fonfigurations) is discussedrnin chapter one as a necessary backaround for the understandingrnof the orbit theory of particles in a special confiqura~·rntion presented in the last chapter.rnFundamental concepts regarding- confinina and heating ofrnplasma and the energy irlterchange bet~een waves and plasmarnparticles have been dealt ~lith in chapters blo and three.rnI>lith the help of circularly polarized fields and arncoordinate system that rotates with E, the nature of thernaveraqeforce and pseudoj1otential, instantantaneous rate ofrnenergy gain ane. its dependence on angle X have been inves·tiqatedrnin chapter four