HHFW Propagation and Damping Properties on NSTX versus B$_{\Phi }$ and Antenna k$_{\vert \vert }$

HHFW RF power delivered to the core plasma of NSTX is strongly reduced as the launched wavelength is increased -- for B$_{\Phi }$ = 4.5 kG, heating is $\sim $ 1/2 as effective for k$_{\vert \vert }$ at -7m$^{-1}$ as at 14m$^{-1}$ and $\sim $ 1/10 as effective at -3m$^{-1}$. Measured edge ion heating, attributable to parametric decay (PDI), increases with wavelength as well but does not increase fast enough to account for the observed power loss. Surface fast waves (FW) may enhance both PDI and also losses in sheaths and structures around the machine -- FW fields propagate closer to the wall with decreasing B$_{\Phi }$ and k$_{\vert \vert }$ (n$_{onset}\propto {\rm B}_{\Phi }$* k$_{\vert \vert }^{2})$. Experiments at several k$_{\vert \vert }$ and B$_{\Phi }$ values suggest strong propagating FW effects on heating. A dramatic increase in core heating was observed at -7m$^{-1}$ when B$_{\Phi }$ was increased to 5.5 kG -- central Te near 4 keV at P$_{RF}$ = 2 MW -- and reduced core heating was observed at B$_{\Phi }$= 3 kG. Also, the far-field RF poloidal magnetic field increased a factor of $\sim $ 3 when k$_{\vert \vert }$ was reduced from 14m$^{-1}$ to -3m$^{-1}$, suggesting a large increase in wall/sheath power loss. The results of these experiments and their implications for the role of surface wave losses will be discussed.