Helicon waves in FRC configurations

RF_Pisa is a full wave code that has previously been used to model HHFW in the LAPD device, as well as ICRH, ECH, mode conversion and minority ion heating in FRC geometry [1,2]. Recently, it has been extended to model the so-called Helicon regime. Waves in this regime are whistler-type waves with a two-branch dispersion relation and characteristic frequencies higher than the Lower Hybrid frequency. The two types of waves, referred to as Trivelpiece-Gould and Helicon, can access specific plasma density values only and transfer energy to the plasma through Landau and collisional dampings. Here through RF_Pisa simulations we first review and discuss the dispersion relation of the Helicon waves beyond the well-known limit cases that can be recovered analytically and then we present a series of results obtained for different plasma and antenna scenarios. Quantities of interest that shall be discussed include wave-plasma coupling, energy and momentum deposition, mode impedance as well as resistance spectra and resonances. Full 3D reconstructions for multi-phase antenna configurations shall be presented.

[1] H. Gota et al., Nuclear Fusion 59, 112009 (2019); [2] F. Ceccherini et al., APS DPP-Meeting 2017