Accessibility of the lower hybrid resonance in thermonuclear devices

The condition for efficient coupling of a high-frequency wave at the lower hybrid resonance is discussed for grazing-angle incidence. Scaling laws are derived, which show that the optimistic results recently produced numerically by Puri and Tutter cannot be extrapolated to densities of thermonuclear interest. It is concluded that the Stix-Golant condition for accessibility remains a necessary condition in practice.