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High impedance surfaces or electromagnetic band gap (EBG) surfaces have proved themselves to be useful in wireless communications applications due to their unique characteristics such as no propagating surface wave support, no conduction of RF current for a given bandwidth, in‐phase electromagnetic reflection and non‐inverted image of the electric charge in front of them [1]. These characteristics make possible to design compact antennas achieving better performance in terms of radiation and input impedance. ICRF and LH antennas in plasma experiments can take advantage of using EBG surfaces. One of the main issues in ICRF plasma heating is the low power coupling of the plasma facing antenna. The adoption of EBG surfaces in the ICRF antenna structure and the advantages offered by a predictive designing tool as TOPICA [2] offer the possibility to improve significantly the coupled power to plasma. The adoption of EBG surfaces in the LH waveguides permits to reduce the major dimension of waveguides not affect...

In recent years electromagnetic (RF) plasma generation and acceleration concepts for plasma-based propulsion systems have received growing interest, inasmuch as they can yield continuous thrust as well as highly controllable and wide-ranging exhaust velocities. The acceleration units mostly adopt the Ion Cyclotron Resonance Frequency (ICRF)—a proven technology in fusion experiments for transferring large RF powers into magnetized plasmas, and also used by the VASIMR propulsion system. In this work we propose and demonstrate the use of TOPICA code to design and optimize the ICRF antenna of a typical acceleration stage. To this end, TOPICA was extended to cope with magnetized cylindrically-symmetric radially-inhomogeneous warm plasmas, which required coding a new module charged with solving Maxwell’s equations within the plasma to obtain the relevant Green’s function ~Y(m;kz) in the Fourier domain, i.e. the relation between the transverse magnetic and electric fields at the air-plasma interface. Then, calculating the antenna input impedance—and hence the loading—relies on an integral-equation formulation and subsequent finite-element weighted-residual solution scheme for the self-consistent evaluation of the current density distribution on the conducting bodies and at the air-plasma interface.

An antenna array is designed for ion cyclotron resonance heating (ICRH) for the IGNITOR experiment, planned to operate in the 70–140 MHz frequency range. The design is based on the conventional strap antenna element, and in our proposed design each strap is fed by a RF power generator via a coaxial cable and a tuning and matching system. The coupling properties of the antenna are calculated with a slab model of the plasma. We consider first a two-dimensional problem to obtain the parameters of the transmission line model for the strap and feeder currents; the current profile thus obtained is then used in a three-dimensional simulation of the antenna that yields the radiation resistance; the input impedance of the straps is then obtained from the radiation resistance and the line parameters. Two methods to obtain the strap input impedance are compared. The first is based on a distributed concept of the radiated power, i.e. introducing a resistance per unit length equal to the ratio between the radiation re...