Lower-hybrid plasma heating via a new launcher – the multijunction grill

A new multijunction grill-type launcher has been tested on the Petula-B tokamak. In this new launcher, the RF power is divided by means of an E-plane junction, and the phase between each resultant wave is obtained by a suitable reduction in the height of the waveguides. Data obtained on Petula-B indicate that both the heating efficiency (4.5 eV × 1013 cm−3kW−1) and the parametric dependences of the reflection coefficient are very similar to those of a conventional grill. Therefore, such a multijunction grill may greatly simplify the construction of grills considered for use in future large-scale tokamaks.