ABSTRACT
Since the early days of research in ECR plasmas in 1980s, heating and confinement in electron cyclotron resonance (ECR) plasmas were brought about by electromagnetic coils. Coils arranged on either side of the experimental device can produce an axial magnetic field. Depending upon the application, the axial field can be linear, diverging, or in the form of a magnetic mirror. A linear field [1-3] has been used in plasma experiments, while a diverging field [4,5] is known to be beneficial for particle directionality to a downstream plasma processing area or for controlling the energy of the ions flowing along the field lines [6]. Recently, there are several experiments on utilizing a diverging field for plasma thrusters [7-9]. The mirror field is routinely used in ion sources [10-13]. In these field configurations, the waves are mainly launched in the K||B mode, often referred to as the whistler mode.
