Lower hybrid parametric instabilities—Nonuniform pump waves and tokamak applications

Resonant Parametric Excitation in Lower-hybrid Heating of Tokamak Plasma*

Absorption of lower hybrid waves in the scrape off layer of a diverted tokamak

The goal of the Lower Hybrid Current Drive (LHCD) system on the Alcator C-Mod tokamak is to investigate current profile control under plasma conditions relevant to future devices such as ITER and DEMO. Experimental observations of an LHCD " density limit " for C-Mod are presented in this paper. Bremsstrahlung emission from relativistic fast electrons in the core plasma drops suddenly above line...

Characterization of onset of parametric decay instability of lower hybrid waves

The goal of the lower hybrid current drive (LHCD) program on Alcator C-Mod is to develop and optimize ITERrelevant steady-state plasmas by controlling the current density profile. Using a 4x16 waveguide array, over 1 MW of LH power at 4.6 GHz has been successfully coupled to the plasmas. However, current drive efficiency precipitously drops as the line averaged density (ne) increases above 1020...

Measurements of the parallel wavenumber of lower hybrid waves in the scrape-off layer of a high-density tokamak

Excitation and trapping of lower hybrid waves in striations

The theory of lower hybrid LH waves trapped in striations in warm ionospheric plasma in the three-dimensional case is presented. A specific mechanism of trapping associated with the linear transformation of waves is discussed. It is shown analytically that such trapping can take place in elongated plasma depletions with the frequencies below and above the lower hybrid resonance frequency of the...