As we previously mentioned under these conditions no longitudinal surface waves are found in the slab model either. But non-longitudinal surface waves are present in the slab. The continua are marked. For the results of the eigenmode calculations we immediately turn to the case . As in the slab model KHI sets in when forward modes have to cross backward cut-off regions.
Resonant instability occurs if forward modes have to cross backward continua.
This can be seen in Fig. 8 . The continua are marked. The same discussions as in the slab geometry apply here.