The Inductively Coupled Array Discharge (INCA)

A novel concept for tailored collisionless electron heating is realized by the Inductively Coupled Array Discharge [1]. A planar array of small coils generates a phase correlated vortex electric field structure with well-defined resonances in velocity space. The discharge based on this concept operates efficiently at low pressures and has the property of easy upscaling to square-meter size. The upscaling is supported by a smart wiring which keeps the overall impedance basically constant, i.e. independent of the size. The basic idea was first proposed in 2014 and studied by simulation [2]. A kinetic model of the stochastic heating mechanism is presented in [3]. It is shown that the heating is indeed non-local in the plane of the vortex fields but local in the vertical coordinate. The mean heating power per area, the complex conductivity, the complex damping constant, and an effective stochastic collision frequency are calculated. Conditions for effective stochastic heating are provided. Experimentally INCA has been demonstrated to work equally well in a variety of feed gases, including strongly electronegative gases [1,5,6]. Recently, the role of the individual coil form and the potential of optimization has been investigated. It is shown that differences between the idealized assumption in the theory and the actual experimental field structures are effectively filtered out in Fourier space [6]. In summary, INCA works well and stable under basically all conditions.